An extraterrestrial vortex is a
vortex
In fluid dynamics, a vortex ( : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in th ...
that occurs on planets and natural satellites other than
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 ...
that have sufficient atmospheres. Most observed extraterrestrial vortices have been seen in large
cyclone
In meteorology, a cyclone () is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above (opposite to an anti ...
s, or
anticyclone
An anticyclone is a weather phenomenon defined as a large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere as viewed from abov ...
s. However, occasional
dust storm
A dust storm, also called a sandstorm, is a meteorological phenomenon common in arid and semi-arid regions. Dust storms arise when a gust front or other strong wind blows loose sand and dirt from a dry surface. Fine particles are transporte ...
s have been known to produce vortices on
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
and
Titan. Various spacecraft missions have recorded evidence of past and present extraterrestrial vortices. The largest extraterrestrial vortices are found on the
gas giant
A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" ...
s,
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 ...
and
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 ...
, and the
ice giant
An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. There are two ice giants in the Solar System: Uranus and Neptune.
In astrophysics and planetary science t ...
s,
Uranus
Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...
and
Neptune
Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times ...
.
Mercury
Due to
Mercury's thin atmosphere, it does not experience weather-like storms or other atmospheric weather phenomena such as clouds, winds, or rain. Rather unusually,
Mercury
Mercury commonly refers to:
* Mercury (planet), the nearest planet to the Sun
* Mercury (element), a metallic chemical element with the symbol Hg
* Mercury (mythology), a Roman god
Mercury or The Mercury may also refer to:
Companies
* Merc ...
has magnetic 'tornadoes' that were observed by NASA's
Mercury MESSENGER
''MESSENGER'' was a NASA robotic space probe that orbited the planet Mercury between 2011 and 2015, studying Mercury's chemical composition, geology, and magnetic field. The name is a backronym for "Mercury Surface, Space Environment, Geoche ...
during a flyby in 2008. The tornadoes are twisted bundles of magnetic fields that connect Mercury's magnetic field to Space.
Venus
Venus Express
''Venus Express'' (VEX) was the first Venus exploration mission of the European Space Agency (ESA). Launched in November 2005, it arrived at Venus in April 2006 and began continuously sending back science data from its polar orbit around Venus. ...
observed two large shape-shifting vortices on
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 ...
' poles (
polar vortices) in 2006 on one of its close-up flybys of the planet. The south pole was seen to have a large, constantly changing, double-eye vortex through high-resolution infrared measurements obtained by the VIRTIS instrument on Venus Express. The cause of the double-eyed vortex is unknown but the polar vortices are caused by the
Hadley Cell
The Hadley cell, named after George Hadley, is a global-scale tropical atmospheric circulation that features air rising near the equator, flowing poleward at a height of 10 to 15 kilometers above the earth's surface, descending in the subtropics, ...
atmospheric circulation of the lower atmosphere. Unusually, neither of the double vortices at the south pole ever line up and are located at slightly different altitudes. The southern pole's cyclone-like storm is roughly the size of Europe. In addition, the southern polar vortex is constantly changing shape but the cause is still unknown.
In 1979, NASA's
Pioneer Venus
The Pioneer Venus project was part of the Pioneer program consisting of two spacecraft, the Pioneer Venus Orbiter and the Pioneer Venus Multiprobe, launched to Venus in 1978. The program was managed by NASA's Ames Research Center.
The Pio ...
observed a double vortex cyclone at the north pole. There haven't been many more close-up observations of the north pole since Pioneer Venus.
Since most of the planet's water has escaped to space, Venus does not experience rain like Earth does. However, there has been evidence of lightning on Venus as confirmed by data from Venus Express. The lightning on Venus is different than the lightning on all other planets as it is associated with sulfuric acid clouds instead of water clouds. The magnetometer instrument on Venus Express detected electrical discharges when the spacecraft was orbiting close to the upper atmosphere of Venus. Most storms form high up in the atmosphere about 25 miles from the surface and all precipitation evaporates about 20 miles above the surface.
Mars
![Mars Before and During Global Dust Storm](https://upload.wikimedia.org/wikipedia/commons/f/f6/Mars_Before_and_During_Global_Dust_Storm.jpg)
Most of the observed atmospheric events on
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
are
dust storm
A dust storm, also called a sandstorm, is a meteorological phenomenon common in arid and semi-arid regions. Dust storms arise when a gust front or other strong wind blows loose sand and dirt from a dry surface. Fine particles are transporte ...
s which can sometimes disrupt enough dust to be seen from Earth. Many large dust storms occur every year on Mars but even more rare are the global dust storms that Mars experiences on average every 6 Earth years. NASA has observed global dust storms in 1971, 1977, 1982, 1994, 2001, 2007, and 2018. While these massive dust storms do cause problems for rovers and spacecraft operating on solar power, the winds on Mars top out at , less than half as strong as hurricane-force winds on Earth, which is not enough to rip apart mechanical equipment.
While Mars is most known for its recurring dust storms, it still experiences cyclone-like storms and polar vortices similar to Earth.
On April 27, 1999, a rare cyclone in diameter was detected by the
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...
in the northern
polar
Polar may refer to:
Geography
Polar may refer to:
* Geographical pole, either of two fixed points on the surface of a rotating body or planet, at 90 degrees from the equator, based on the axis around which a body rotates
* Polar climate, the c ...
region of
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
. It consisted of three cloud bands wrapped around a massive diameter eye, and contained features similar to storms that have been detected in the poles of Earth (see:
polar low
A polar low is a mesoscale, short-lived atmospheric low pressure system (depression) that is found over the ocean areas poleward of the main polar front in both the Northern and Southern Hemispheres, as well as the Sea of Japan. The systems usua ...
). It was only observed briefly, as it seemed to be dissipating when it was imaged six hours later, and was not seen on later imaging passes. Several other cyclones were imaged in about the same area: the March 2, 2001 cyclone, January 19, 2003 cyclone, and the November 27, 2004 cyclone.
In addition, NASA's 2001 Mars Odyssey Spacecraft observed a cold, low density, polar vortex in the planet's atmosphere above latitudes 70 degrees north and higher. NASA determined that every winter a polar vortex forms over the north pole above the atmosphere. The vortex and atmosphere are separated by a transition zone where strong winds encircle the pole and terrestrial jet stream-like characteristics. The stability of these annular polar vortices are still being researched as scientists believe Martian dust may play a role in their formation.
Jupiter
Jupiter's atmosphere is lined with hundreds of vortices most likely to be cyclones, or anticyclones, similar to those on Earth.
Voyager and
Cassini discovered that, unlike the terrestrial atmosphere, 90% of Jovian vortices are anticyclones, meaning they rotate in the opposite direction of the planet's rotation. Many cyclones have showed up and disappeared over the years with some even merging to form larger cyclones.
When
NASA's Juno Spacecraft arrived at Jupiter in 2016, it observed giant cyclones encircling the north and south poles of the planet. Nine large cyclones were spotted around the north pole and 6 around the south pole. Upon further flybys, Juno spotted another cyclone at the south pole and noticed that 6 of the 7 cyclones formed a hexagonal arrangement around the cyclone at the center of the south pole. Data from Juno has shown that this storm system is stable and there have been no signs of vortices attempting to merge.
The
Great Red Spot on Jupiter is, by far, the largest extraterrestrial anticyclone (or cyclone) known. The Great Red Spot is located in the southern hemisphere and has wind speeds greater than any storm ever measured on Earth. New data from Juno found that the storm penetrates into Jupiter's atmosphere about . The giant storm has been monitored since 1830 but has possibly survived for over 350 years. Over 100 years ago, the Great Red Spot was well over two Earths wide but has been shrinking ever since. When
Voyagers 1 and
2 flew by in 1979, they measured the massive cyclone to be twice Earth's diameter. Measurements today from telescopes have measured a diameter of 1.3 Earths wide.
Oval BA (or Red Spot Jr.) is the second-largest storm on Jupiter and formed from the merging of 3 smaller cyclones in 2000. It is located just to the south of the Great Red Spot and has been increasing in size in recent years, slowly turning a more uniform white.
The Great Dark Spot is a feature observed near Jupiter's north pole in 2000 by the
Cassini–Huygens
''Cassini–Huygens'' ( ), commonly called ''Cassini'', was a space research, space-research mission by NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a space probe to study the planet Saturn and its system, i ...
spacecraft that was a short-lived dark cloud that grew to the size of the Great Red Spot before disappearing after 11 weeks. The phenomenon is speculated by scientists to be a side-effect of strong auroras on Jupiter.
Saturn
![Dragon Storm](https://upload.wikimedia.org/wikipedia/commons/3/3a/Dragon_Storm.jpg)
Every
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 ...
year, about 28 Earth years, Saturn has massive planet-circling storms, called
Great White Spot
Saturn's Great White Spot in 2011.
The Great White Spot, also known as Great White Oval, on Saturn, named by analogy to Jupiter's Great Red Spot, are periodic storms that are large enough to be visible from Earth by telescope by their character ...
s. The Great White Spots are short-lived but can impact the atmosphere and temperature of the planet for up to 3 Earth years after their collapse. The spots can be several thousand kilometers wide and can even run into their own tails and fade out once they circle the planet.
Most storms on Saturn occur in a zone in the southern hemisphere dubbed 'storm alley' by scientists for its high abundance of storm activity. Storm alley lies 35 degrees south of the equator and it is still unknown why there is such a large quantity of storms that form here. There is also a long-lived storm known as the
Dragon Storm Dragon Storm may refer to:
* Dragon Storm (game), a role-playing game and collectible card game
* Dragon Storm (astronomy)
The Dragon Storm is a giant thunderstorm located in Saturn's Southern hemisphere, which is labeled as the "storm alley" reg ...
, which flares occasionally on Saturn's southern latitudes. Cassini detected bursts of radio emissions from the storm on multiple occasions, similar to the short bursts of static that are produced from lightning on earth.
On October 11, 2006, the
Cassini-Huygens spacecraft took images of a storm with a well-defined distinct
eyewall
The eye is a region of mostly calm weather at the center of tropical cyclones. The eye of a storm is a roughly circular area, typically in diameter. It is surrounded by the ''eyewall'', a ring of towering thunderstorms where the most severe weat ...
over the south pole 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 ...
. It was across, with storms in the eyewall reaching high. The storm had wind speeds of and appeared to be stationary over Saturn's south pole.
Saturn currently holds the record for the longest continuous thunderstorm in the Solar System with a storm that Cassini observed back in 2009 that lasted for over 8 months. Instruments on Cassini detected powerful radio waves coming from lightning discharges in Saturn's atmosphere. These radio waves are about 10,000 times stronger than the ones emitted by terrestrial lightning.
A
hexagonal cyclone in Saturn's north pole has been spotted since the passage of
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 ...
and
2, and was first imaged by
Cassini on January 3, 2009. It is just under in diameter, with a depth of about , and encircles the north pole of the ringed planet at roughly 78° N latitude.
Titan
Titan is very similar to Earth and is the only known planetary body with a substantial atmosphere and stable bodies of surface liquid that still exist. Titan experiences storms similar to Earth, but instead of water there is methane and ethane liquids on Titan.
Data from
Cassini found that Titan experiences dust storms similar to those on Earth and Mars. When Titan is in equinox, strong down-burst winds raise micron-sized particles up from sand dunes and create dust storms. The dust storms are relatively short but create intense infrared bright spots in the atmosphere, which is how Cassini detected them.
Cassini captured an image of a south polar vortex on Titan in June 2012. Titan was also found to have a northern polar vortex with similar characteristics as the southern polar vortex. Scientists later found that these vortices formed during the winter, meaning they were seasonal, similar to Earth's polar vortices.
The south polar vortex was imaged again in 2013 and it was determined that the vortex forms higher up in the atmosphere than previously thought. The hazy atmosphere that Titan has leaves the moon unilluminated in the Sun's rays but the image of the vortex showed a bright spot on the south pole. Scientists derived that the vortex is high up in the atmosphere, possibly above the haze, because it can still be illuminated by the Sun.
Uranus
![Uranus Dark spot](https://upload.wikimedia.org/wikipedia/commons/5/52/Uranus_Dark_spot.jpg)
Uranus was long thought to be atmospherically static due to the lack of storms observed, but in recent years astronomers have started to see more storm activity on the planet. However, there is still limited data on Uranus as it is so far away from Earth and hard to observe regularly.
In 2018,
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...
(HST) captured an image of
Uranus
Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...
that showed a large, bright, polar cap over the north pole. The storm is thought to be long-lived and scientists theorize it formed by seasonal changes in atmospheric flow.
In 2006, Hubble Space Telescope imaged the
Uranus Dark Spot
The climate of Uranus is heavily influenced by both its lack of internal heat, which limits atmospheric activity, and by its extreme axial tilt, which induces intense seasonal variation. Uranus' atmosphere is remarkably bland in comparison to the ...
. Scientists saw similarities between the Uranus Dark Spot (UDS) and the
Great Dark Spot
The Great Dark Spot (also known as GDS-89, for Great Dark Spot, 1989) was one of a series of dark spots on Neptune similar in appearance to Jupiter's Great Red Spot. In 1989, GDS-89 was the first Great Dark Spot on Neptune to be observed by NASA's ...
s (GDS) on
Neptune
Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times ...
, although UDS was much smaller. GDS were thought to be anticyclonic vortices in Neptune's atmosphere and UDS is assumed to be similar in nature.
In 1998, HST captured infrared images of multiple storms raging on Uranus due to seasonal changes.
Neptune
![PIA00064 Neptune's Dark Spot (D2), 1989](https://upload.wikimedia.org/wikipedia/commons/4/47/PIA00064_Neptune%27s_Dark_Spot_%28D2%29%2C_1989.jpg)
The
Great Dark Spot
The Great Dark Spot (also known as GDS-89, for Great Dark Spot, 1989) was one of a series of dark spots on Neptune similar in appearance to Jupiter's Great Red Spot. In 1989, GDS-89 was the first Great Dark Spot on Neptune to be observed by NASA's ...
was an Earth-sized vortex observed in the southern hemisphere of
Neptune
Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times ...
by
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 ...
in 1989. The storm had some of the highest recorded wind speeds in the Solar System at approximately and rotated around the planet once every 18.3 hours.
When the
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...
turned its gaze to Neptune in 1994, the spot had vanished; but the storm causing the spot might have continued lower in the atmosphere.
The
Small Dark Spot
The Small Dark Spot, sometimes also called Dark Spot 2 or The Wizard's Eye, was an Extraterrestrial Storms, extraterrestrial vortex on the planet Neptune. It was the second largest southern Cyclone, cyclonic storm on the planet in 1989, when ''V ...
(sometimes called Great Dark Spot 2 or
Wizard's Eye) was another vortex observed by Voyager 2 in its 1989 pass of Neptune. This spot is located approximately 30° further south on the planet and transits the planet once every 16.1 hours.
The Small Dark Spot's distinct appearance comes from white methane-ice clouds which upwell through the center of the storm and give it an eye-like appearance. This storm had also apparently vanished by the time the Hubble Space Telescope inspected the planet in 1994.
A total of 4 additional dark spots have been observed on Neptune since the discovery of the first two. A small storm which formed in the southern hemisphere in 2015 was tracked by Amy Simon and her team at
NASA Goddard
The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C. in Greenbelt, Maryland, United States. Established on May 1, 1959 as NASA's first space flight center, GSFC empl ...
(she is now part of the Outer Planet Atmospheres Legacy project) from its birth to its death. While focused on tracking this small storm the team was able to discover the emergence of a giant spot the size of the Great Dark Spot at 23° North of the equator in 2018.
The observations taken by this team were able to point to the importance of "companion clouds" in identifying the storms that cause these spots even while a dark spot was not present.
This team also concluded that the storms have a likely lifespan of 2 years with a life of up to 6 years being possible, and will look to study the shape and speed of dark spots in the future.
References
{{reflist, 2
Planetary spots
Types of cyclone