Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...
is the cavity created in the
solar wind
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sola ...
by the planet's
magnetic field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
. Extending up to seven million kilometers in the Sun's direction and almost to the orbit of
Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
in the opposite direction, Jupiter's
magnetosphere
In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dynam ...
is the largest and most powerful of any planetary magnetosphere in the
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
, and by volume the largest known continuous structure in the Solar System after the
heliosphere
The heliosphere is the magnetosphere, astrosphere and outermost atmospheric layer of the Sun. It takes the shape of a vast, bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding interstell ...
. Wider and flatter than the
Earth's magnetosphere
In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dyn ...
, Jupiter's is stronger by an
order of magnitude
An order of magnitude is an approximation of the logarithm of a value relative to some contextually understood reference value, usually 10, interpreted as the base of the logarithm and the representative of values of magnitude one. Logarithmic dis ...
, while its
magnetic moment
In electromagnetism, the magnetic moment is the magnetic strength and orientation of a magnet or other object that produces a magnetic field. Examples of objects that have magnetic moments include loops of electric current (such as electromagnets ...
is roughly 18,000 times larger. The existence of Jupiter's magnetic field was first inferred from observations of radio emissions at the end of the 1950s and was directly observed by the
Pioneer 10
''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ach ...
spacecraft in 1973.
Jupiter's internal magnetic field is generated by electrical currents in the planet's outer core, which is composed of liquid
metallic hydrogen
Metallic hydrogen is a phase of hydrogen in which it behaves like an electrical conductor. This phase was predicted in 1935 on theoretical grounds by Eugene Wigner and Hillard Bell Huntington.
At high pressure and temperatures, metallic hydrogen c ...
. Volcanic eruptions on Jupiter's moon Io eject large amounts of
sulfur dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activ ...
gas into space, forming a large
torus
In geometry, a torus (plural tori, colloquially donut or doughnut) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis that is coplanar with the circle.
If the axis of revolution does not tou ...
around the planet. Jupiter's magnetic field forces the torus to rotate with the same
angular velocity
In physics, angular velocity or rotational velocity ( or ), also known as angular frequency vector,(UP1) is a pseudovector representation of how fast the angular position or orientation of an object changes with time (i.e. how quickly an objec ...
and direction as the planet. The torus in turn loads the magnetic field with
plasma
Plasma or plasm may refer to:
Science
* Plasma (physics), one of the four fundamental states of matter
* Plasma (mineral), a green translucent silica mineral
* Quark–gluon plasma, a state of matter in quantum chromodynamics
Biology
* Blood pla ...
, in the process stretching it into a pancake-like structure called a magnetodisk. In effect, Jupiter's magnetosphere is internally driven, shaped primarily by Io's plasma and its own rotation, rather than by the
solar wind
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sola ...
as at Earth's magnetosphere. Strong currents in the magnetosphere generate permanent
aurorae
An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in polar regions of Earth, high-latitude regions (around the Arctic and Antarctic). Auroras display ...
around the planet's poles and intense variable radio emissions, which means that Jupiter can be thought of as a very weak
radio pulsar
A pulsar (from ''pulsating radio source'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Ea ...
. Jupiter's aurorae have been observed in almost all parts of the
electromagnetic spectrum
The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies.
The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from ...
, including
infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
,
visible
Visibility, in meteorology, is a measure of the distance at which an object or light can be seen.
Visibility may also refer to:
* A measure of turbidity in water quality control
* Interferometric visibility, which quantifies interference contrast ...
,
ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
and
soft X-rays
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30 ...
.
The action of the magnetosphere traps and accelerates particles, producing intense belts of
radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes:
* ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...
similar to Earth's Van Allen belts, but thousands of times stronger. The interaction of energetic particles with the surfaces of Jupiter's largest
moons
A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are often colloquially referred to as ''moons'' ...
markedly affects their chemical and physical properties. Those same particles also affect and are affected by the motions of the particles within Jupiter's tenuous planetary ring system. Radiation belts present a significant hazard for spacecraft and potentially to human space travellers.
Structure
Jupiter's magnetosphere is a complex structure comprising a
bow shock
In astrophysics, a bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby flowing ambient plasma such as the solar wind. For Earth and other magnetized planets, it is the boundary at which the speed of ...
,
magnetosheath
The magnetosheath is the region of space between the magnetopause and the bow shock of a planet's magnetosphere. The regularly organized magnetic field generated by the planet becomes weak and irregular in the magnetosheath due to interaction with ...
,
magnetopause
The magnetopause is the abrupt boundary between a magnetosphere and the surrounding plasma. For planetary science, the magnetopause is the boundary between the planet's magnetic field and the solar wind. The location of the magnetopause is d ...
,
magnetotail
In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dynamo. ...
, magnetodisk, and other components. The magnetic field around Jupiter emanates from a number of different sources, including fluid circulation at the planet's core (the internal field), electrical currents in the plasma surrounding Jupiter and the currents flowing at the boundary of the planet's magnetosphere. The magnetosphere is embedded within the plasma of the
solar wind
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sola ...
, which carries the
interplanetary magnetic field
The interplanetary magnetic field (IMF), now more commonly referred to as the heliospheric magnetic field (HMF), is the component of the solar magnetic field that is dragged out from the solar corona by the solar wind flow to fill the Solar Syst ...
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
's, is generated by an internal
dynamo
file:DynamoElectricMachinesEndViewPartlySection USP284110.png, "Dynamo Electric Machine" (end view, partly section, )
A dynamo is an electrical generator that creates direct current using a commutator (electric), commutator. Dynamos were the f ...
supported by the circulation of a conducting fluid in its
outer core
Earth's outer core is a fluid layer about thick, composed of mostly iron and nickel that lies above Earth's solid inner core and below its mantle. The outer core begins approximately beneath Earth's surface at the core-mantle boundary and e ...
. But whereas Earth's core is made of molten
iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
and
nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...
, Jupiter's is composed of
metallic hydrogen
Metallic hydrogen is a phase of hydrogen in which it behaves like an electrical conductor. This phase was predicted in 1935 on theoretical grounds by Eugene Wigner and Hillard Bell Huntington.
At high pressure and temperatures, metallic hydrogen c ...
. As with Earth's, Jupiter's magnetic field is mostly a
dipole
In physics, a dipole () is an electromagnetic phenomenon which occurs in two ways:
*An electric dipole deals with the separation of the positive and negative electric charges found in any electromagnetic system. A simple example of this system i ...
, with north and south magnetic poles at the ends of a single magnetic axis. On Jupiter the north pole of the dipole (where magnetic field lines point radially outward) is located in the planet's northern hemisphere and the south pole of the dipole lies in its southern hemisphere. This is opposite from the Earth. Jupiter's field also has
quadrupole
A quadrupole or quadrapole is one of a sequence of configurations of things like electric charge or current, or gravitational mass that can exist in ideal form, but it is usually just part of a multipole expansion of a more complex structure refl ...
,
octupole
A multipole expansion is a mathematical series representing a function that depends on angles—usually the two angles used in the spherical coordinate system (the polar and azimuthal angles) for three-dimensional Euclidean space, \R^3. Similarly t ...
and higher components, though they are less than one-tenth as strong as the dipole component.Khurana, 2004, pp. 3–5
The dipole is tilted roughly 10° from Jupiter's axis of rotation; the tilt is similar to that of the Earth (11.3°). Its equatorial field strength is about 417.0 μT (4.170 G), which corresponds to a dipole
magnetic moment
In electromagnetism, the magnetic moment is the magnetic strength and orientation of a magnet or other object that produces a magnetic field. Examples of objects that have magnetic moments include loops of electric current (such as electromagnets ...
of about 2.83 T· m3. This makes Jupiter's magnetic field about 20 times stronger than Earth's, and its magnetic moment ~20,000 times larger. Jupiter's magnetic field rotates at the same speed as the region below its atmosphere, with a period of 9 h 55 m. No changes in its strength or structure had been observed since the first measurements were taken by the
Pioneer
Pioneer commonly refers to a settler who migrates to previously uninhabited or sparsely inhabited land.
In the United States pioneer commonly refers to an American pioneer, a person in American history who migrated west to join in settling and dev ...
spacecraft in the mid-1970s, until 2019. Analysis of observations from the
Juno
Juno commonly refers to:
*Juno (mythology), the Roman goddess of marriage and queen of the gods
*Juno (film), ''Juno'' (film), 2007
Juno may also refer to:
Arts, entertainment and media Fictional characters
*Juno, in the film ''Jenny, Juno''
*Ju ...
spacecraft show a small but measurable change from the planet's magnetic field observed during the Pioneer era. In particular, Jupiter has a region of strongly non-dipolar field, known as the "Great Blue Spot", near the equator. This may be roughly analogous to the Earth's
South Atlantic Anomaly
The South Atlantic Anomaly (SAA) is an area where Earth's inner Van Allen radiation belt comes closest to Earth's surface, dipping down to an altitude of . This leads to an increased flux of energetic particles in this region and exposes orbiti ...
. This region shows signs of large
secular variation
The secular variation of a time series is its long-term, non-periodic variation (see decomposition of time series). Whether a variation is perceived as secular or not depends on the available timescale: a variation that is secular over a timescale ...
s.
Size and shape
Jupiter's internal magnetic field prevents the
solar wind
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sola ...
, a stream of ionized particles emitted by the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
, from interacting directly with its atmosphere, and instead diverts it away from the planet, effectively creating a cavity in the solar wind flow, called a magnetosphere, composed of a
plasma
Plasma or plasm may refer to:
Science
* Plasma (physics), one of the four fundamental states of matter
* Plasma (mineral), a green translucent silica mineral
* Quark–gluon plasma, a state of matter in quantum chromodynamics
Biology
* Blood pla ...
different from that of the solar wind.Khurana, 2004, pp. 1–3 The Jovian magnetosphere is so large that the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
and its visible
corona
Corona (from the Latin for 'crown') most commonly refers to:
* Stellar corona, the outer atmosphere of the Sun or another star
* Corona (beer), a Mexican beer
* Corona, informal term for the coronavirus SARS-CoV-2, which causes the COVID-19 di ...
would fit inside it with room to spare.Russel, 1993, pp. 715–717 If one could see it from Earth, it would appear five times larger than the
full moon
The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective. This occurs when Earth is located between the Sun and the Moon (when the ecliptic coordinate system, ecliptic longitudes of the Sun and Moon opp ...
in the sky despite being nearly 1700 times farther away.
As with Earth's magnetosphere, the boundary separating the denser and colder solar wind's plasma from the hotter and less dense one within Jupiter's magnetosphere is called the
magnetopause
The magnetopause is the abrupt boundary between a magnetosphere and the surrounding plasma. For planetary science, the magnetopause is the boundary between the planet's magnetic field and the solar wind. The location of the magnetopause is d ...
. The distance from the magnetopause to the center of the planet is from 45 to 100 ''R''J (where ''R''J=71,492 km is the radius of Jupiter) at the
subsolar point
The subsolar point on a planet is the point at which its sun is perceived to be directly overhead (at the zenith); that is, where the sun's rays strike the planet exactly perpendicular to its surface. It can also mean the point closest to the sun ...
—the unfixed point on the surface at which the Sun would appear directly overhead to an observer. The position of the magnetopause depends on the pressure exerted by the solar wind, which in turn depends on
solar activity
Solar phenomena are natural phenomena which occur within the atmosphere of the Sun. These phenomena take many forms, including solar wind, radio wave flux, solar flares, coronal mass ejections, coronal heating and sunspots.
These phenomena are ...
.Russell, 2001, pp. 1015–1016 In front of the magnetopause (at a distance from 80 to 130 ''R''J from the planet's center) lies the
bow shock
In astrophysics, a bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby flowing ambient plasma such as the solar wind. For Earth and other magnetized planets, it is the boundary at which the speed of ...
, a
wake
Wake or The Wake may refer to:
Culture
*Wake (ceremony), a ritual which takes place during some funeral ceremonies
*Wakes week, an English holiday tradition
* Parish Wake, another name of the Welsh ', the fairs held on the local parish's patron s ...
-like disturbance in the solar wind caused by its collision with the magnetosphere.
Krupp
The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
, 2004, pp. 15–16Russel, 1993, pp. 725–727 The region between the bow shock and magnetopause is called the
magnetosheath
The magnetosheath is the region of space between the magnetopause and the bow shock of a planet's magnetosphere. The regularly organized magnetic field generated by the planet becomes weak and irregular in the magnetosheath due to interaction with ...
.
At the opposite side of the planet, the solar wind stretches Jupiter's magnetic field lines into a long, trailing
magnetotail
In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dynamo. ...
, which sometimes extends well beyond the orbit of
Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
. The structure of Jupiter's magnetotail is similar to Earth's. It consists of two lobes (blue areas in the figure), with the magnetic field in the southern lobe pointing toward Jupiter, and that in the northern lobe pointing away from it. The lobes are separated by a thin layer of plasma called the tail
current sheet
A current sheet is an electric current that is confined to a surface, rather than being spread through a volume of space. Current sheets feature in magnetohydrodynamics (MHD), the study of the behavior of electrically conductive fluids: if ther ...
(orange layer in the middle).Khurana, 2004, pp. 17–18
The shape of Jupiter's magnetosphere described above is sustained by the neutral sheet current (also known as the magnetotail current), which flows with Jupiter's rotation through the tail
plasma sheet
In the magnetosphere, the plasma sheet is a sheet-like region of denser (0.3-0.5 ions/cm3 versus 0.01-0.02 in the lobes) hot plasma and lower magnetic field near the equatorial plane, between the magnetosphere's north and south lobes.
A magneto ...
, the tail currents, which flow against Jupiter's rotation at the outer boundary of the magnetotail, and the magnetopause currents (or Chapman–Ferraro currents), which flow against rotation along the dayside magnetopause. These currents create the magnetic field that cancels the internal field outside the magnetosphere. They also interact substantially with the solar wind.Kivelson, 2005, pp. 303–313
Jupiter's magnetosphere is traditionally divided into three parts: the inner, middle and outer magnetosphere. The inner magnetosphere is located at distances closer than 10 ''R''J from the planet. The magnetic field within it remains approximately dipole, because contributions from the currents flowing in the magnetospheric equatorial plasma sheet are small. In the middle (between 10 and 40 ''R''J) and outer (further than 40 ''R''J) magnetospheres, the magnetic field is not a dipole, and is seriously disturbed by its interaction with the plasma sheet (see magnetodisk below).
Role of Io
Although overall the shape of Jupiter's magnetosphere resembles that of the Earth's, closer to the planet its structure is very different. Jupiter's volcanically active moon Io is a strong source of plasma in its own right, and loads Jupiter's magnetosphere with as much as 1,000 kg of new material every second.Khurana, 2004, pp. 5–7 Strong volcanic eruptions on Io emit huge amounts of
sulfur dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activ ...
, a major part of which is
dissociated
Dissociation in chemistry is a general process in which molecules (or ionic compounds such as salts, or complexes) separate or split into other things such as atoms, ions, or radicals, usually in a reversible manner. For instance, when an acid ...
into atoms and
ionized
Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule ...
ultraviolet radiation
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
, producing ions of
sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
and
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
. Further electron impacts produce higher charge state, resulting in a plasma of S+, O+, S2+, O2+ and S3+.
Krupp
The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
, 2004, pp. 3–4 They form the ''Io plasma torus'': a thick and relatively cool ring of plasma encircling Jupiter, located near Io's orbit. The plasma temperature within the torus is 10–100 eV (100,000–1,000,000 K), which is much lower than that of the particles in the radiation belts—10 keV (100 million K). The plasma in the torus is forced into co-rotation with Jupiter, meaning both share the same period of rotation. The Io torus fundamentally alters the dynamics of the Jovian magnetosphere.
Krupp
The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
, 2004, pp. 1–3
As a result of several processes—
diffusion
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
and
interchange instability
The interchange instability is a type of plasma instability seen in magnetic fusion energy that is driven by the gradients in the magnetic pressure in areas where the confining magnetic field is curved.
The name of the instability refers to th ...
being the main escape mechanisms—the plasma slowly leaks away from Jupiter.
Krupp
The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
, 2004, pp. 4–7 As the plasma moves further from the planet, the radial currents flowing within it gradually increase its velocity, maintaining co-rotation. These radial currents are also the source of the magnetic field's azimuthal component, which as a result bends back against the rotation. The
particle number density
The particle number (or number of particles) of a thermodynamic system, conventionally indicated with the letter ''N'', is the number of constituent particles in that system. The particle number is a fundamental parameter in thermodynamics which is ...
of the plasma decreases from around 2,000 cm−3 in the Io torus to about 0.2 cm−3 at a distance of 35 ''R''J.Khurana, 2004, pp. 10–12 In the middle magnetosphere, at distances greater than 10 ''R''J from Jupiter, co-rotation gradually breaks down and the plasma begins to rotate more slowly than the planet. Eventually at the distances greater than roughly 40 ''R''J (in the outer magnetosphere) this plasma is no longer confined by the magnetic field and leaves the magnetosphere through the magnetotail.Russell, 2001, pp. 1024–1025 As cold, dense plasma moves outward, it is replaced by hot, low-density plasma, with temperatures of up to 20
keV Kev can refer to:
Given name
* Kev Adams, French comedian, actor, screenwriter and film producer born Kevin Smadja in 1991
* Kevin Kev Carmody (born 1946), Indigenous Australian singer-songwriter
* Kev Coghlan (born 1988), Scottish Grand Prix motor ...
(200 million K) or higher) moving in from the outer magnetosphere. Some of this plasma, adiabatically heated as it approaches Jupiter,Khurana, 2004, pp. 20–21 may form the radiation belts in Jupiter's inner magnetosphere.
Magnetodisk
While Earth's magnetic field is roughly teardrop-shaped, Jupiter's is flatter, more closely resembling a disk, and "wobbles" periodically about its axis. The main reasons for this disk-like configuration are the
centrifugal force
In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis which is paralle ...
from the co-rotating plasma and thermal pressure of hot plasma, both of which act to stretch Jupiter's
magnetic field line
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
s, forming a flattened pancake-like structure, known as the magnetodisk, at the distances greater than 20 ''R''J from the planet.Russell, 2001, pp. 1021–1024 The magnetodisk has a thin current sheet at the middle plane, approximately near the
magnetic equator
Magnetic dip, dip angle, or magnetic inclination is the angle made with the horizontal by the Earth's magnetic field lines. This angle varies at different points on the Earth's surface. Positive values of inclination indicate that the magnetic fi ...
. The magnetic field lines point away from Jupiter above the sheet and towards Jupiter below it. The load of plasma from Io greatly expands the size of the Jovian magnetosphere, because the magnetodisk creates an additional internal pressure which balances the pressure of the solar wind. In the absence of Io the distance from the planet to the magnetopause at the subsolar point would be no more than 42 ''R''J, whereas it is actually 75 ''R''J on average.
The configuration of the magnetodisk's field is maintained by the azimuthal
ring current
A ring current is an electric current carried by charged particles trapped in a planet's magnetosphere. It is caused by the longitudinal drift of energetic (10–200 k eV) particles.
Earth's ring current
Earth's ring current is responsible f ...
(not an analog of Earth's ring current), which flows with rotation through the equatorial plasma sheet.Kivelson, 2005, pp. 315–316 The
Lorentz force
In physics (specifically in electromagnetism) the Lorentz force (or electromagnetic force) is the combination of electric and magnetic force on a point charge due to electromagnetic fields. A particle of charge moving with a velocity in an elect ...
resulting from the interaction of this current with the planetary magnetic field creates a
centripetal force
A centripetal force (from Latin ''centrum'', "center" and ''petere'', "to seek") is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous c ...
, which keeps the co-rotating plasma from escaping the planet. The total ring current in the equatorial current sheet is estimated at 90–160 million
ampere
The ampere (, ; symbol: A), often shortened to amp,SI supports only the use of symbols and deprecates the use of abbreviations for units. is the unit of electric current in the International System of Units (SI). One ampere is equal to elect ...
The main driver of Jupiter's magnetosphere is the planet's rotation.Blanc, 2005, pp. 250–253 In this respect Jupiter is similar to a device called a
Unipolar generator
A homopolar generator is a DC electrical generator comprising an electrically conductive disc or cylinder rotating in a plane perpendicular to a uniform static magnetic field. A potential difference is created between the center of the disc and th ...
. When Jupiter rotates, its ionosphere moves relatively to the dipole magnetic field of the planet. Because the dipole magnetic moment points in the direction of the rotation, the
Lorentz force
In physics (specifically in electromagnetism) the Lorentz force (or electromagnetic force) is the combination of electric and magnetic force on a point charge due to electromagnetic fields. A particle of charge moving with a velocity in an elect ...
, which appears as a result of this motion, drives negatively charged electrons to the poles, while positively charged ions are pushed towards the equator.Cowley, 2001, pp. 1069–76 As a result, the poles become negatively charged and the regions closer to the equator become positively charged. Since the magnetosphere of Jupiter is filled with highly conductive plasma, the
electrical circuit
An electrical network is an interconnection of electrical components (e.g., batteries, resistors, inductors, capacitors, switches, transistors) or a model of such an interconnection, consisting of electrical elements (e.g., voltage sources, ...
is closed through it. A current called the direct current flows along the magnetic field lines from the ionosphere to the equatorial plasma sheet. This current then flows radially away from the planet within the equatorial plasma sheet and finally returns to the planetary ionosphere from the outer reaches of the magnetosphere along the field lines connected to the poles. The currents that flow along the magnetic field lines are generally called field-aligned or
Birkeland current
A Birkeland current (also known as field-aligned current) is a set of electrical currents that flow along geomagnetic field lines connecting the Earth's magnetosphere to the Earth's high latitude ionosphere. In the Earth's magnetosphere, the curr ...
s. The radial current interacts with the planetary magnetic field, and the resulting Lorentz force accelerates the magnetospheric plasma in the direction of planetary rotation. This is the main mechanism that maintains co-rotation of the plasma in Jupiter's magnetosphere.
The current flowing from the ionosphere to the plasma sheet is especially strong when the corresponding part of the plasma sheet rotates slower than the planet. As mentioned above, co-rotation breaks down in the region located between 20 and 40 ''R''J from Jupiter. This region corresponds to the magnetodisk, where the magnetic field is highly stretched.Blanc, 2005, pp. 254–261 The strong direct current flowing into the magnetodisk originates in a very limited latitudinal range of about ° from the Jovian magnetic poles. These narrow circular regions correspond to Jupiter's main auroral ovals. (See below.)Cowley, 2001, pp. 1083–87 The return current flowing from the outer magnetosphere beyond 50 ''R''J enters the Jovian ionosphere near the poles, closing the electrical circuit. The total radial current in the Jovian magnetosphere is estimated at 60 million–140 million amperes.
The acceleration of the plasma into the co-rotation leads to the transfer of energy from the Jovian rotation to the
kinetic energy
In physics, the kinetic energy of an object is the energy that it possesses due to its motion.
It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its accele ...
of the plasma. In that sense, the Jovian magnetosphere is powered by the planet's rotation, whereas the Earth's magnetosphere is powered mainly by the solar wind.
Interchange instability and reconnection
The main problem encountered in deciphering the dynamics of the Jovian magnetosphere is the transport of heavy cold plasma from the Io torus at 6 ''R''J to the outer magnetosphere at distances of more than 50 ''R''J. The precise mechanism of this process is not known, but it is hypothesized to occur as a result of plasma diffusion due to interchange instability. The process is similar to the Rayleigh-Taylor instability in
hydrodynamics
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) and ...
. In the case of the Jovian magnetosphere,
centrifugal force
In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis which is paralle ...
plays the role of gravity; the heavy liquid is the cold and dense Ionian (i.e. pertaining to Io) plasma, and the light liquid is the hot, much less dense plasma from the outer magnetosphere. The instability leads to an exchange between the outer and inner parts of the magnetosphere of
flux tube
A flux tube is a generally tube-like ( cylindrical) region of space containing a magnetic field, B, such that the cylindrical sides of the tube are everywhere parallel to the magnetic field lines. It is a graphical visual aid for visualizing a mag ...
s filled with plasma. The buoyant empty flux tubes move towards the planet, while pushing the heavy tubes, filled with the Ionian plasma, away from Jupiter. This interchange of flux tubes is a form of magnetospheric
turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...
.Russell, 2008
This highly hypothetical picture of the flux tube exchange was partly confirmed by the
Galileo spacecraft
''Galileo'' was an American robotic space probe that studied the planet Jupiter and its moons, as well as the asteroids Gaspra and Ida. Named after the Italian astronomer Galileo Galilei, it consisted of an orbiter and an entry probe. It was ...
, which detected regions of sharply reduced plasma density and increased field strength in the inner magnetosphere. These voids may correspond to the almost empty flux tubes arriving from the outer magnetosphere. In the middle magnetosphere, Galileo detected so-called injection events, which occur when hot plasma from the outer magnetosphere impacts the magnetodisk, leading to increased flux of energetic particles and a strengthened magnetic field.
Krupp
The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
, 2004, pp. 7–9 No mechanism is yet known to explain the transport of cold plasma outward.
When flux tubes loaded with the cold Ionian plasma reach the outer magnetosphere, they go through a
reconnection
Magnetic reconnection is a physical process occurring in highly conducting plasmas in which the magnetic topology is rearranged and magnetic energy is converted to kinetic energy, thermal energy, and particle acceleration. Magnetic reconnectio ...
process, which separates the magnetic field from the plasma. The former returns to the inner magnetosphere in the form of flux tubes filled with hot and less dense plasma, while the latter are probably ejected down the magnetotail in the form of
plasmoid
A plasmoid is a coherent structure of plasma and magnetic fields. Plasmoids have been proposed to explain natural phenomena such as ball lightning, magnetic bubbles in the magnetosphere, and objects in cometary tails, in the solar wind, in th ...
s—large blobs of plasma. The reconnection processes may correspond to the global reconfiguration events also observed by the Galileo spacecraft, which occurred regularly every 2–3 days. The reconfiguration events usually included rapid and chaotic variation of the magnetic field strength and direction, as well as abrupt changes in the motion of the plasma, which often stopped co-rotating and began flowing outward. They were mainly observed in the dawn sector of the night magnetosphere.
Krupp
The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
, 2004, pp. 11–14 The plasma flowing down the tail along the open field lines is called the planetary wind.Khurana, 2004, pp. 18–19
The reconnection events are analogues to the magnetic substorms in the Earth's magnetosphere. The difference seems to be their respective energy sources: terrestrial substorms involve storage of the solar wind's energy in the magnetotail followed by its release through a reconnection event in the tail's neutral current sheet. The latter also creates a plasmoid which moves down the tail.Russell, 2001, p. 1011 Conversely, in Jupiter's magnetosphere the rotational energy is stored in the magnetodisk and released when a plasmoid separates from it.
Influence of the solar wind
Whereas the dynamics of the Jovian magnetosphere mainly depend on internal sources of energy, the solar wind probably has a role as well,
Nichols Nichols may refer to:
People
*Nichols (surname)
*Nichol, a surname
Places Canada
* Nichols Islands, Nunavut
United States
* Nichols, California, an unincorporated community
* Nichols Canyon, Los Angeles, California
* Nichols, Connecticut
* Nic ...
, 2006, pp. 393–394 particularly as a source of high-energy
proton
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
s. The structure of the outer magnetosphere shows some features of a solar wind-driven magnetosphere, including a significant dawn–dusk asymmetry. In particular, magnetic field lines in the dusk sector are bent in the opposite direction to those in the dawn sector. In addition, the dawn magnetosphere contains open field lines connecting to the magnetotail, whereas in the dusk magnetosphere, the field lines are closed. All these observations indicate that a solar wind driven reconnection process, known on Earth as the Dungey cycle, may also be taking place in the Jovian magnetosphere.
The extent of the solar wind's influence on the dynamics of Jupiter's magnetosphere is currently unknown;
Krupp
The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
, 2004, pp. 18–19 however, it could be especially strong at times of elevated solar activity.
Nichols Nichols may refer to:
People
*Nichols (surname)
*Nichol, a surname
Places Canada
* Nichols Islands, Nunavut
United States
* Nichols, California, an unincorporated community
* Nichols Canyon, Los Angeles, California
* Nichols, Connecticut
* Nic ...
, 2006, pp. 404–405 The auroral radio, optical and X-ray emissions, as well as
synchrotron
A synchrotron is a particular type of cyclic particle accelerator, descended from the cyclotron, in which the accelerating particle beam travels around a fixed closed-loop path. The magnetic field which bends the particle beam into its closed p ...
emissions from the radiation belts all show correlations with solar wind pressure, indicating that the solar wind may drive plasma circulation or modulate internal processes in the magnetosphere.
Emissions
Aurorae
Jupiter demonstrates bright, persistent aurorae around both poles. Unlike Earth's aurorae, which are transient and only occur at times of heightened solar activity, Jupiter's aurorae are permanent, though their intensity varies from day to day. They consist of three main components: the main ovals, which are bright, narrow (less than 1000 km in width) circular features located at approximately 16° from the magnetic poles; the satellites' auroral spots, which correspond to the footprints of the magnetic field lines connecting Jupiter's ionosphere with those of its largest moons, and transient polar emissions situated within the main ovals (elliptical field may prove to be a better description).Palier, 2001, pp. 1171–73
Bhardwaj
Bhardwaj is a surname used by Brahmins and rajputs relating to sage Bharadwaja gotra in India.
Notable people
Notable people with the surname include
Sports
* Anil Bhardwaj (cricketer) (born 1954), Indian cricketer
* B. M. Rahul Bharadwaj (bor ...
, 2000, pp. 311–316 Auroral emissions have been detected in almost all parts of the electromagnetic spectrum from radio waves to X-rays (up to 3 keV); they are most frequently observed in the mid-infrared (wavelength 3–4 μm and 7–14 μm) and far ultraviolet spectral regions (wavelength 120–180 nm).
Bhardwaj
Bhardwaj is a surname used by Brahmins and rajputs relating to sage Bharadwaja gotra in India.
Notable people
Notable people with the surname include
Sports
* Anil Bhardwaj (cricketer) (born 1954), Indian cricketer
* B. M. Rahul Bharadwaj (bor ...
, 2000, p. 342
The main ovals are the dominant part of the Jovian aurorae. They have roughly stable shapes and locations, but their intensities are strongly modulated by the solar wind pressure—the stronger solar wind, the weaker the aurorae.Cowley, 2003, pp. 49–53 As mentioned above, the main ovals are maintained by the strong influx of electrons accelerated by the electric potential drops between the magnetodisk plasma and the Jovian ionosphere.
Bhardwaj
Bhardwaj is a surname used by Brahmins and rajputs relating to sage Bharadwaja gotra in India.
Notable people
Notable people with the surname include
Sports
* Anil Bhardwaj (cricketer) (born 1954), Indian cricketer
* B. M. Rahul Bharadwaj (bor ...
, 2000, pp. 316–319 These electrons carry field aligned currents, which maintain the plasma's co-rotation in the magnetodisk. The potential drops develop because the sparse plasma outside the equatorial sheet can only carry a current of a limited strength without driving instabilities and producing potential drops. The precipitating electrons have energy in the range 10–100 keV and penetrate deep into the atmosphere of Jupiter, where they ionize and excite molecular hydrogen causing ultraviolet emission.
Bhardwaj
Bhardwaj is a surname used by Brahmins and rajputs relating to sage Bharadwaja gotra in India.
Notable people
Notable people with the surname include
Sports
* Anil Bhardwaj (cricketer) (born 1954), Indian cricketer
* B. M. Rahul Bharadwaj (bor ...
, 2000, pp. 306–311 The total energy input into the ionosphere is 10–100 TW.
Bhardwaj
Bhardwaj is a surname used by Brahmins and rajputs relating to sage Bharadwaja gotra in India.
Notable people
Notable people with the surname include
Sports
* Anil Bhardwaj (cricketer) (born 1954), Indian cricketer
* B. M. Rahul Bharadwaj (bor ...
, 2000, p. 296 In addition, the currents flowing in the ionosphere heat it by the process known as
Joule heating
Joule heating, also known as resistive, resistance, or Ohmic heating, is the process by which the passage of an electric current through a conductor (material), conductor produces heat.
Joule's first law (also just Joule's law), also known in c ...
. This heating, which produces up to 300 TW of power, is responsible for the strong infrared radiation from the Jovian aurorae and partially for the heating of the thermosphere of Jupiter.
Spots were found to correspond to the Galilean moons Io,
Europa
Europa may refer to:
Places
* Europe
* Europa (Roman province), a province within the Diocese of Thrace
* Europa (Seville Metro), Seville, Spain; a station on the Seville Metro
* Europa City, Paris, France; a planned development
* Europa Cliff ...
Clarke
Clarke is a surname which means "clerk". The surname is of English and Irish origin and comes from the Latin . Variants include Clerk and Clark. Clarke is also uncommonly chosen as a given name.
Irish surname origin
Clarke is a popular surname i ...
, 2002 They develop because the co-rotation of the plasma interacts with the moons and is slowed in their vicinity. The brightest spot belongs to Io, which is the main source of the plasma in the magnetosphere (see above). The Ionian auroral spot is thought to be related to Alfvén currents flowing from the Jovian to Ionian ionosphere. Europa's is similar but much dimmer, because it has a more tenuous atmosphere and is a weaker plasma source. Europa's atmosphere is produced by sublimation of water ice from its surfaces, rather than the volcanic activity which produces Io's atmosphere.Blanc, 2005, pp. 277–283 Ganymede has an internal magnetic field and a
magnetosphere
In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dynam ...
of its own. The interaction between this magnetosphere and that of Jupiter produces currents due to
magnetic reconnection
Magnetic reconnection is a physical process occurring in highly conducting plasmas in which the magnetic topology is rearranged and magnetic energy is converted to kinetic energy, thermal energy, and particle acceleration. Magnetic reconnectio ...
. The auroral spot associated with Callisto is probably similar to that of Europa, but has only been seen once as of June, 2019. Normally, magnetic field lines connected to Callisto touch Jupiter's atmosphere very close to or along the main auroral oval, making it difficult to detect Callisto's auroral spot.
Bright arcs and spots sporadically appear within the main ovals. These transient phenomena are thought to be related to interaction with either the solar wind or the dynamics of the outer magnetosphere. The magnetic field lines in this region are believed to be open or to map onto the magnetotail. The secondary ovals are sometimes observed inside the main oval and may be related to the boundary between open and closed magnetic field lines or to the polar
cusp
A cusp is the most pointed end of a curve. It often refers to cusp (anatomy), a pointed structure on a tooth.
Cusp or CUSP may also refer to:
Mathematics
* Cusp (singularity), a singular point of a curve
* Cusp catastrophe, a branch of bifurca ...
s.Palier, 2001, pp. 1170–71 The polar auroral emissions could be similar to those observed around Earth's poles: appearing when electrons are accelerated towards the planet by potential drops, during reconnection of solar magnetic field with that of the planet. The regions within the main ovals emits most of auroral X-rays. The spectrum of the auroral X-ray radiation consists of
spectral line
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to iden ...
s of highly ionized oxygen and sulfur, which probably appear when energetic (hundreds of kiloelectronvolts) S and O ions precipitate into the polar atmosphere of Jupiter. The source of this precipitation remains unknown but this is inconsistent with the theory that these magnetic field lines are open and connect to the solar wind.Elsner, 2005, pp. 419–420
Jupiter at radio wavelengths
Jupiter is a powerful source of
radio wave
Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (short ...
s in the spectral regions stretching from several
kilohertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one h ...
to tens of
megahertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or Cycle per second, cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, me ...
. Radio waves with
frequencies
Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...
of less than about 0.3 MHz (and thus wavelengths longer than 1 km) are called the Jovian kilometric radiation or KOM. Those with frequencies in the interval of 0.3–3 MHz (with wavelengths of 100–1000 m) are called the hectometric radiation or HOM, while emissions in the range 3–40 MHz (with wavelengths of 10–100 m) are referred to as the decametric radiation or DAM. The latter radiation was the first to be observed from Earth, and its approximately 10-hour periodicity helped to identify it as originating from Jupiter. The strongest part of decametric emission, which is related to Io and to the Io–Jupiter current system, is called Io-DAM.
Zarka
Zarqa ( ar, الزرقاء) is the capital of Zarqa Governorate in Jordan. Its name means "the blue (city)". It had a population of 635,160 inhabitants in 2015, and is the most populous city in Jordan after Amman.
Geography
Zarqa is located in t ...
, 1998, pp. 20,160–168
The majority of these emissions are thought to be produced by a mechanism called "cyclotron maser instability", which develops close to the auroral regions. Electrons moving parallel to the magnetic field precipitate into the atmosphere while those with a sufficient perpendicular velocity are reflected by the converging magnetic field. This results in an unstable velocity distribution. This velocity distribution spontaneously generates radio waves at the local electron
cyclotron frequency
Cyclotron resonance describes the interaction of external forces with charged particles experiencing a magnetic field, thus already moving on a circular path. It is named after the cyclotron, a cyclic particle accelerator that utilizes an oscillati ...
. The electrons involved in the generation of radio waves are probably those carrying currents from the poles of the planet to the magnetodisk.
Zarka
Zarqa ( ar, الزرقاء) is the capital of Zarqa Governorate in Jordan. Its name means "the blue (city)". It had a population of 635,160 inhabitants in 2015, and is the most populous city in Jordan after Amman.
Geography
Zarqa is located in t ...
, 1998, pp. 20, 173–181 The intensity of Jovian radio emissions usually varies smoothly with time. However, there are short and powerful bursts (S bursts) of emission superimposed on the more gradual variations and which can outshine all other components. The total emitted power of the DAM component is about 100 GW, while the power of all other HOM/KOM components is about 10 GW. In comparison, the total power of Earth's radio emissions is about 0.1 GW.
Jupiter's radio and particle emissions are strongly modulated by its rotation, which makes the planet somewhat similar to a
pulsar
A pulsar (from ''pulsating radio source'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Ea ...
.
Hill
A hill is a landform that extends above the surrounding terrain. It often has a distinct Summit (topography), summit.
Terminology
The distinction between a hill and a mountain is unclear and largely subjective, but a hill is universally con ...
, 1995 This periodical modulation is probably related to asymmetries in the Jovian magnetosphere, which are caused by the tilt of the magnetic moment with respect to the rotational axis as well as by high-latitude
magnetic anomalies
In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying ...
. The physics governing Jupiter's radio emissions is similar to that of radio pulsars. They differ only in the scale, and Jupiter can be considered a very small
radio pulsar
A pulsar (from ''pulsating radio source'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Ea ...
too. In addition, Jupiter's radio emissions strongly depend on solar wind pressure and, hence, on
solar activity
Solar phenomena are natural phenomena which occur within the atmosphere of the Sun. These phenomena take many forms, including solar wind, radio wave flux, solar flares, coronal mass ejections, coronal heating and sunspots.
These phenomena are ...
.
In addition to relatively long-wavelength radiation, Jupiter also emits
synchrotron radiation
Synchrotron radiation (also known as magnetobremsstrahlung radiation) is the electromagnetic radiation emitted when relativistic charged particles are subject to an acceleration perpendicular to their velocity (). It is produced artificially in ...
(also known as the Jovian decimetric radiation or DIM radiation) with frequencies in the range of 0.1–15 GHz (wavelength from 3 m to 2 cm),. These emissions are from relativistic electrons trapped in the inner radiation belts of the planet. The energy of the electrons that contribute to the DIM emissions is from 0.1 to 100 MeV,Santos-Costa, 2001 while the leading contribution comes from the electrons with energy in the range 1–20 MeV.
Bolton
Bolton (, locally ) is a large town in Greater Manchester in North West England, formerly a part of Lancashire. A former mill town, Bolton has been a production centre for textiles since Flemish people, Flemish weavers settled in the area i ...
, 2002 This radiation is well understood and was used since the beginning of the 1960s to study the structure of the planet's magnetic field and radiation belts.
Zarka
Zarqa ( ar, الزرقاء) is the capital of Zarqa Governorate in Jordan. Its name means "the blue (city)". It had a population of 635,160 inhabitants in 2015, and is the most populous city in Jordan after Amman.
Geography
Zarqa is located in t ...
, 2005, pp. 384–385 The particles in the radiation belts originate in the outer magnetosphere and are adiabatically accelerated, when they are transported to the inner magnetosphere. However, this requires a source population of moderately high energy electrons (>> 1 keV), and the origin of this population is not well understood.
Jupiter's magnetosphere ejects streams of high-energy electrons and ions (energy up to tens
megaelectronvolt
In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacuum. ...
s), which travel as far as Earth's orbit.
Krupp
The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
, 2004, pp. 17–18 These streams are highly
collimated
A collimated beam of light or other electromagnetic radiation has parallel rays, and therefore will spread minimally as it propagates. A perfectly collimated light beam, with no divergence, would not disperse with distance. However, diffraction pr ...
and vary with the rotational period of the planet like the radio emissions. In this respect as well, Jupiter shows similarity to a pulsar.
Interaction with rings and moons
Jupiter's extensive magnetosphere envelops its ring system and the orbits of all four
Galilean satellites
The Galilean moons (), or Galilean satellites, are the four largest moons of Jupiter: Io, Europa, Ganymede, and Callisto. They were first seen by Galileo Galilei in December 1609 or January 1610, and recognized by him as satellites of Jupiter ...
. Orbiting near the magnetic equator, these bodies serve as sources and sinks of magnetospheric plasma, while energetic particles from the magnetosphere alter their surfaces. The particles
sputter
In physics, sputtering is a phenomenon in which microscopic particles of a solid material are ejected from its surface, after the material is itself bombarded by energetic particles of a plasma or gas. It occurs naturally in outer space, and can ...
off material from the surfaces and create chemical changes via
radiolysis
Radiolysis is the dissociation of molecules by ionizing radiation. It is the cleavage of one or several chemical bonds resulting from exposure to high-energy flux. The radiation in this context is associated with ionizing radiation; radiolysis is ...
.
Johnson
Johnson is a surname of Anglo-Norman origin meaning "Son of John". It is the second most common in the United States and 154th most common in the world. As a common family name in Scotland, Johnson is occasionally a variation of ''Johnston'', a ...
, 2004, pp. 1–2 The plasma's co-rotation with the planet means that the plasma preferably interacts with the moons' trailing hemispheres, causing noticeable hemispheric asymmetries.
Johnson
Johnson is a surname of Anglo-Norman origin meaning "Son of John". It is the second most common in the United States and 154th most common in the world. As a common family name in Scotland, Johnson is occasionally a variation of ''Johnston'', a ...
, 2004, pp. 3–5
Close to Jupiter, the planet's rings and small moons absorb high-energy particles (energy above 10 keV) from the radiation belts. This creates noticeable gaps in the belts' spatial distribution and affects the decimetric synchrotron radiation. In fact, the existence of Jupiter's rings was first hypothesized on the basis of data from the
Pioneer 11
''Pioneer 11'' (also known as ''Pioneer G'') is a robotic space probe launched by NASA on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, solar winds, and cosmic rays. It was the first probe to encounter ...
spacecraft, which detected a sharp drop in the number of high-energy ions close to the planet.
Burns Burns may refer to:
* Burn, an injury (plural)
People:
* Burns (surname), includes list of people and characters
Business:
* Burns London, a British guitar maker
Places:
;In the United States
* Burns, Colorado, unincorporated community in Eagle ...
, 2004, pp. 1–2 The planetary magnetic field strongly influences the motion of sub-micrometer ring particles as well, which acquire an electrical charge under the influence of solar
ultraviolet radiation
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
. Their behavior is similar to that of co-rotating
ion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...
s.
Burns Burns may refer to:
* Burn, an injury (plural)
People:
* Burns (surname), includes list of people and characters
Business:
* Burns London, a British guitar maker
Places:
;In the United States
* Burns, Colorado, unincorporated community in Eagle ...
, 2004, pp. 12–14 Resonant interactions between the co-rotation and the particles' orbital motion has been used to explain the creation of Jupiter's innermost halo ring (located between 1.4 and 1.71 ''R''J). This ring consists of sub-micrometer particles on highly
inclined
Incline, inclined, inclining, or inclination may refer to:
*Grade (slope), the tilt, steepness, or angle from horizontal of a topographic feature (hillside, meadow, etc.) or constructed element (road, railway, field, etc.)
*Slope, the tilt, steepn ...
and
eccentric
Eccentricity or eccentric may refer to:
* Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal"
Mathematics, science and technology Mathematics
* Off-center, in geometry
* Eccentricity (graph theory) of a v ...
orbits.
Burns Burns may refer to:
* Burn, an injury (plural)
People:
* Burns (surname), includes list of people and characters
Business:
* Burns London, a British guitar maker
Places:
;In the United States
* Burns, Colorado, unincorporated community in Eagle ...
, 2004, pp. 10–11 The particles originate in the main ring; however, when they drift toward Jupiter, their orbits are modified by the strong 3:2 Lorentz resonance located at 1.71 ''R''J, which increases their inclinations and eccentricities. Another 2:1 Lorentz resonance at 1.4 Rj defines the inner boundary of the halo ring.
Burns Burns may refer to:
* Burn, an injury (plural)
People:
* Burns (surname), includes list of people and characters
Business:
* Burns London, a British guitar maker
Places:
;In the United States
* Burns, Colorado, unincorporated community in Eagle ...
, 2004, pp. 17–19
All Galilean moons have thin atmospheres with surface pressures in the range 0.01–1 nbar, which in turn support substantial
ionosphere
The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an ...
s with electron densities in the range of 1,000–10,000 cm−3.Kivelson, 2004, pp. 2–4 The co-rotational flow of cold magnetospheric plasma is partially diverted around them by the currents induced in their ionospheres, creating wedge-shaped structures known as Alfvén wings.Kivelson, 2004, pp. 8–10 The interaction of the large moons with the co-rotational flow is similar to the interaction of the
solar wind
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sola ...
with the non-magnetized planets like
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...
, although the co-rotational speed is usually subsonic (the speeds vary from 74 to 328 km/s), which prevents the formation of a
bow shock
In astrophysics, a bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby flowing ambient plasma such as the solar wind. For Earth and other magnetized planets, it is the boundary at which the speed of ...
.Kivelson, 2004, pp. 1–2 The pressure from the co-rotating plasma continuously strips gases from the moons' atmospheres (especially from that of Io), and some of these atoms are ionized and brought into co-rotation. This process creates gas and plasma tori in the vicinity of moons' orbits with the Ionian torus being the most prominent. In effect, the Galilean moons (mainly Io) serve as the principal plasma sources in Jupiter's inner and middle magnetosphere. Meanwhile, the energetic particles are largely unaffected by the Alfvén wings and have free access to the moons' surfaces (except Ganymede's).
Cooper
Cooper, Cooper's, Coopers and similar may refer to:
* Cooper (profession), a maker of wooden casks and other staved vessels
Arts and entertainment
* Cooper (producers), alias of Dutch producers Klubbheads
* Cooper (video game character), in ...
, 2001, pp. 137,139
The icy Galilean moons,
Europa
Europa may refer to:
Places
* Europe
* Europa (Roman province), a province within the Diocese of Thrace
* Europa (Seville Metro), Seville, Spain; a station on the Seville Metro
* Europa City, Paris, France; a planned development
* Europa Cliff ...
Callisto Callisto most commonly refers to:
*Callisto (mythology), a nymph
*Callisto (moon), a moon of Jupiter
Callisto may also refer to:
Art and entertainment
*''Callisto series'', a sequence of novels by Lin Carter
*''Callisto'', a novel by Torsten Kro ...
, all generate induced magnetic moments in response to changes in Jupiter's magnetic field. These varying magnetic moments create dipole magnetic fields around them, which act to compensate for changes in the ambient field. The induction is thought to take place in subsurface layers of salty water, which are likely to exist in all of Jupiter's large icy moons. These underground oceans can potentially harbor life, and evidence for their presence was one of the most important discoveries made in the 1990s by
spacecraft
A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, p ...
.Kivelson, 2004, pp. 10–11
The interaction of the Jovian magnetosphere with Ganymede, which has an intrinsic magnetic moment, differs from its interaction with the non-magnetized moons. Ganymede's internal magnetic field carves a cavity inside Jupiter's magnetosphere with a diameter of approximately two Ganymede diameters, creating a mini-magnetosphere within Jupiter's magnetosphere. Ganymede's magnetic field diverts the co-rotating plasma flow around its magnetosphere. It also protects the moon's equatorial regions, where the field lines are closed, from energetic particles. The latter can still freely strike Ganymede's poles, where the field lines are open.Kivelson, 2004, pp. 16–18 Some of the energetic particles are trapped near the equator of Ganymede, creating mini-radiation belts.Williams, 1998, p. 1 Energetic electrons entering its thin atmosphere are responsible for the observed Ganymedian polar aurorae.
Charged particles have a considerable influence on the surface properties of Galilean moons. Plasma originating from Io carries sulfur and
sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
ions farther from the planet,
Cooper
Cooper, Cooper's, Coopers and similar may refer to:
* Cooper (profession), a maker of wooden casks and other staved vessels
Arts and entertainment
* Cooper (producers), alias of Dutch producers Klubbheads
* Cooper (video game character), in ...
, 2001, pp. 154–156 where they are implanted preferentially on the trailing hemispheres of Europa and Ganymede.
Johnson
Johnson is a surname of Anglo-Norman origin meaning "Son of John". It is the second most common in the United States and 154th most common in the world. As a common family name in Scotland, Johnson is occasionally a variation of ''Johnston'', a ...
, 2004, pp. 15–19 On Callisto however, for unknown reasons, sulfur is concentrated on the leading hemisphere.Hibbitts, 2000, p. 1 Plasma may also be responsible for darkening the moons' trailing hemispheres (again, except Callisto's). Energetic electrons and ions, with the flux of the latter being more isotropic, bombard surface ice, sputtering atoms and molecules off and causing
radiolysis
Radiolysis is the dissociation of molecules by ionizing radiation. It is the cleavage of one or several chemical bonds resulting from exposure to high-energy flux. The radiation in this context is associated with ionizing radiation; radiolysis is ...
of water and other
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
s. The energetic particles break water into
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
and
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
, maintaining the thin oxygen atmospheres of the icy moons (since the hydrogen escapes more rapidly). The compounds produced radiolytically on the surfaces of Galilean moons also include
ozone
Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...
and
hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3% ...
. If organics or
carbonate
A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate g ...
s are present,
carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
,
methanol
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...
and carbonic acid can be produced as well. In the presence of sulfur, likely products include sulfur dioxide,
hydrogen disulfide
Hydrogen disulfide is the inorganic compound with the formula H2S2. This hydrogen chalcogenide is a pale yellow volatile liquid with a camphor-like odor. It decomposes readily to hydrogen sulfide (H2S) and elemental sulfur.R. Steudel "Inorgani ...
and
sulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...
.
Johnson
Johnson is a surname of Anglo-Norman origin meaning "Son of John". It is the second most common in the United States and 154th most common in the world. As a common family name in Scotland, Johnson is occasionally a variation of ''Johnston'', a ...
, 2004, pp. 8–13
Oxidant
An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxid ...
s produced by radiolysis, like oxygen and ozone, may be trapped inside the ice and carried downward to the oceans over geologic time intervals, thus serving as a possible energy source for life.
Discovery
The first evidence for the existence of Jupiter's magnetic field came in 1955, with the discovery of the decametric radio emission or DAM.Burke and Franklin, 1955 As the DAM's spectrum extended up to 40
MHz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...
, astronomers concluded that Jupiter must possess a magnetic field with a maximum strength of above 1 milli teslas (10
gauss
Johann Carl Friedrich Gauss (; german: Gauß ; la, Carolus Fridericus Gauss; 30 April 177723 February 1855) was a German mathematician and physicist who made significant contributions to many fields in mathematics and science. Sometimes refer ...
).
Zarka
Zarqa ( ar, الزرقاء) is the capital of Zarqa Governorate in Jordan. Its name means "the blue (city)". It had a population of 635,160 inhabitants in 2015, and is the most populous city in Jordan after Amman.
Geography
Zarqa is located in t ...
, 2005, pp. 371–375
In 1959, observations in the
microwave
Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ran ...
part of the electromagnetic (EM) spectrum (0.1–10
GHz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...
) led to the discovery of the Jovian decimetric radiation (DIM) and the realization that it was
synchrotron radiation
Synchrotron radiation (also known as magnetobremsstrahlung radiation) is the electromagnetic radiation emitted when relativistic charged particles are subject to an acceleration perpendicular to their velocity (). It is produced artificially in ...
Drake
Drake may refer to:
Animals
* A male duck
People and fictional characters
* Drake (surname), a list of people and fictional characters with the family name
* Drake (given name), a list of people and fictional characters with the given name
* ...
, 1959 These synchrotron emissions were used to estimate the number and energy of the electrons around Jupiter and led to improved estimates of the magnetic moment and its tilt.
By 1973 the magnetic moment was known within a factor of two, whereas the tilt was correctly estimated at about 10°. The modulation of Jupiter's DAM by Io (the so-called Io-DAM) was discovered in 1964, and allowed Jupiter's
rotation period
The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...
to be precisely determined.
Zarka
Zarqa ( ar, الزرقاء) is the capital of Zarqa Governorate in Jordan. Its name means "the blue (city)". It had a population of 635,160 inhabitants in 2015, and is the most populous city in Jordan after Amman.
Geography
Zarqa is located in t ...
, 2005, pp. 375–377 The definitive discovery of the Jovian magnetic field occurred in December 1973, when the
Pioneer 10
''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ach ...
spacecraft flew near the planet.
Smith
Smith may refer to:
People
* Metalsmith, or simply smith, a craftsman fashioning tools or works of art out of various metals
* Smith (given name)
* Smith (surname), a family name originating in England, Scotland and Ireland
** List of people wi ...
, 1974
Exploration after 1970
As of 2009 a total of eight spacecraft have flown around Jupiter and all have contributed to the present knowledge of the Jovian magnetosphere. The first space probe to reach Jupiter was
Pioneer 10
''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ach ...
in December 1973, which passed within 2.9 ''R''J from the center of the planet. Its twin
Pioneer 11
''Pioneer 11'' (also known as ''Pioneer G'') is a robotic space probe launched by NASA on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, solar winds, and cosmic rays. It was the first probe to encounter ...
visited Jupiter a year later, traveling along a highly inclined trajectory and approaching the planet as close as 1.6 ''R''J.
Pioneer 10 provided the best coverage available of the inner magnetic field as it passed through the inner radiation belts within 20 ''R''J, receiving an integrated dose of 200,000 rads from
electrons
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no ...
and 56,000 rads from
protons
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
(for a human, a whole body dose of 500 rads would be fatal). The level of radiation at Jupiter was ten times more powerful than Pioneer's designers had predicted, leading to fears that the probe would not survive; however, with a few minor glitches, it managed to pass through the radiation belts, saved in large part by the fact that Jupiter's magnetosphere had "wobbled" slightly upward at that point, moving away from the spacecraft. However, Pioneer 11 did lose most images of Io, as the radiation had caused its imaging photo
polarimeter
A polarimeter is a scientific instrument used to measure the angle of rotation caused by passing polarized light through an optically active substance.Voyager spacecraft had to be redesigned to cope with the massive radiation levels.
Wolverton
Wolverton is a constituent town of Milton Keynes, England. It is located at the northern edge of Milton Keynes, beside the West Coast Main Line, the Grand Union Canal and the river Great Ouse. It is the administrative seat of Wolverton and Gre ...
, 2004, pp. 100–157
Voyagers 1 and 2 arrived at Jupiter in 1979–1980 and traveled almost in its equatorial plane.
Voyager 1
''Voyager 1'' is a space probe launched by NASA on September 5, 1977, as part of the Voyager program to study the outer Solar System and interstellar space beyond the Sun's heliosphere. Launched 16 days after its twin ''Voyager 2'', ''Voya ...
, which passed within 5 ''R''J from the planet's center, was first to encounter the Io plasma torus. It received a radiation dosage one thousand times the lethal level for humans, the damage resulting in serious degradation of some high-resolution images of Io and Ganymede.
Voyager 2
''Voyager 2'' is a space probe launched by NASA on August 20, 1977, to study the outer planets and interstellar space beyond the Sun's heliosphere. As a part of the Voyager program, it was launched 16 days before its twin, ''Voyager 1'', on a ...
passed within 10 ''R''J and discovered the current sheet in the equatorial plane. The next probe to approach Jupiter was ''
Ulysses
Ulysses is one form of the Roman name for Odysseus, a hero in ancient Greek literature.
Ulysses may also refer to:
People
* Ulysses (given name), including a list of people with this name
Places in the United States
* Ulysses, Kansas
* Ulysse ...
'' in 1992, which investigated the planet's polar magnetosphere.
The ''Galileo'' spacecraft, which orbited Jupiter from 1995 to 2003, provided a comprehensive coverage of Jupiter's magnetic field near the equatorial plane at distances up to 100 ''R''J. The regions studied included the magnetotail and the dawn and dusk sectors of the magnetosphere. While Galileo successfully survived in the harsh radiation environment of Jupiter, it still experienced a few technical problems. In particular, the spacecraft's
gyroscope
A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rota ...
s often exhibited increased errors. Several times
electrical arc
An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a prolonged electrical discharge. The current through a normally nonconductive medium such as air produces a plasma; the plasma may produce visible light. ...
s occurred between rotating and non-rotating parts of the spacecraft, causing it to enter safe mode, which led to total loss of the data from the 16th, 18th and 33rd orbits. The radiation also caused phase shifts in ''Galileos ultra-stable
quartz oscillator
A crystal oscillator is an electronic oscillator circuit that uses a piezoelectric crystal as a frequency-selective element. The oscillator frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable cloc ...
.
Fieseler
The Gerhard Fieseler Werke (GFW) in Kassel was a German aircraft manufacturer of the 1930s and 1940s. The company is remembered mostly for its military aircraft built for the Luftwaffe during the Second World War.
History
The firm was founded on ...
, 2002
When the '' Cassini'' spacecraft flew by Jupiter in 2000, it conducted coordinated measurements with ''Galileo''. ''
New Horizons
''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe that was launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research ...
'' passed close to Jupiter in 2007, carrying out a unique investigation of the Jovian magnetotail, traveling as far as 2500 ''R''J along its length.
Krupp
The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
, 2007, p. 216 In July 2016 ''
Juno
Juno commonly refers to:
*Juno (mythology), the Roman goddess of marriage and queen of the gods
*Juno (film), ''Juno'' (film), 2007
Juno may also refer to:
Arts, entertainment and media Fictional characters
*Juno, in the film ''Jenny, Juno''
*Ju ...
'' was inserted into Jupiter orbit, its scientific objectives include exploration of Jupiter's polar magnetosphere. The coverage of Jupiter's magnetosphere remains much poorer than for Earth's magnetic field. Further study is important to further understand the Jovian magnetosphere's dynamics.
In 2003,
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
conducted a conceptual study called "Human Outer Planets Exploration" (HOPE) regarding the future human exploration of the
outer Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
. The possibility was mooted of building a surface base on Callisto, because of the low radiation levels at the moon's distance from Jupiter and its geological stability. Callisto is the only one of Jupiter's Galilean satellites for which human exploration is feasible. The levels of
ionizing radiation
Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...
on Io, Europa and Ganymede are inimical to human life, and adequate protective measures have yet to be devised.Troutman, 2003
Exploration after 2010
The ''Juno'' New Frontiers mission to Jupiter was launched in 2011 and arrived at Jupiter in 2016. It includes a suite of instruments designed to better understand the magnetosphere, including a
magnetometer
A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...
as well as other devices such as a detector for plasma and radio waves called ''Waves''.
The
Jovian Auroral Distributions Experiment
Jovian Auroral Distributions Experiment (JADE) is an instrument that detects and measures ions and electrons around the spacecraft. It is a suite of detectors on the ''Juno'' Jupiter orbiter (launched 2011, orbiting Jupiter since 2016). JADE incl ...
(JADE) instrument should also help to understand the magnetosphere.
''Juno'' revealed a planetary magnetic field rich in spatial variation, possibly due to a relatively large dynamo radius. The most surprising observation until late 2017 was the absence of the expected magnetic signature of intense field aligned currents (
Birkeland currents
A Birkeland current (also known as field-aligned current) is a set of electrical currents that flow along geomagnetic field lines connecting the Earth's magnetosphere to the Earth's high latitude ionosphere. In the Earth's magnetosphere, the cu ...
) associated with the main aurora.
One of the goals of the European Space Agency's
Jupiter Icy Moons Explorer
The Jupiter Icy Moons Explorer (JUICE) is an interplanetary spacecraft in development by the European Space Agency (ESA) with Airbus Defence and Space as the main contractor. The mission will study three of Jupiter's Galilean moons: Ganymede ...
(JUICE) mission, scheduled to launch in April, 2023, is to understand the magnetic field from Ganymede and how it impacts Jupiter. Tianwen-4 is a proposed Chinese mission that will either explore the moon Callisto or gather more information on Io.
Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...