HOME TheInfoList.com
Providing Lists of Related Topics to Help You Find Great Stuff
[::MainTopicLength::#1500] [::ListTopicLength::#1000] [::ListLength::#15] [::ListAdRepeat::#3]

picture info

Sun
The SUN is the star at the center of the Solar System
Solar System
. It is a nearly perfect sphere of hot plasma , with internal convective motion that generates a magnetic field via a dynamo process . It is by far the most important source of energy for life on Earth
Earth
. Its diameter is about 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System. About three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen , carbon , neon , and iron . The Sun
Sun
is a G-type main-sequence star
G-type main-sequence star
(G2V) based on its spectral class . As such, it is informally referred to as a yellow dwarf
[...More...]

"Sun" on:
Wikipedia
Google
Yahoo

picture info

Galactic Plane
The GALACTIC PLANE is the plane in which the majority of a disk-shaped galaxy 's mass lies. The directions perpendicular to the galactic plane point to the GALACTIC POLES. Most often, in actual usage, the terms "galactic plane" and "galactic poles" are used to refer specifically to the plane and poles of the Milky Way , which is the galaxy in which Planet Earth
Earth
is located. Some galaxies are irregular and do not have any well-defined disk. Even in the case of a barred spiral galaxy like the Milky Way, defining the galactic plane is slightly imprecise and arbitrary since the stars are not perfectly coplanar. In 1959 the IAU defined the position of the Milky Way's north galactic pole as exactly RA = 12h 49m, Dec = 27° 24′ in the then-used B1950 epoch ; in the currently-used J2000 epoch, after precession is taken into account, its position is RA 12h 51m 26.282s, Dec 27° 07′ 42.01″
[...More...]

"Galactic Plane" on:
Wikipedia
Google
Yahoo

picture info

Cgs
The CENTIMETRE–GRAM–SECOND SYSTEM OF UNITS (abbreviated CGS or CGS) is a variant of the metric system based on the centimetre as the unit of length , the gram as the unit of mass , and the second as the unit of time . All CGS mechanical units are unambiguously derived from these three base units, but there are several different ways of extending the CGS system to cover electromagnetism . The CGS system has been largely supplanted by the MKS system based on the metre , kilogram , and second, which was in turn extended and replaced by the International System of Units (SI). In many fields of science and engineering, SI is the only system of units in use but there remain certain subfields where CGS is prevalent
[...More...]

"Cgs" on:
Wikipedia
Google
Yahoo

Radiance
In radiometry , RADIANCE is the radiant flux emitted, reflected, transmitted or received by a given surface, per unit solid angle per unit projected area. SPECTRAL RADIANCE is the radiance of a surface per unit frequency or wavelength , depending on whether the spectrum is taken as a function of frequency or of wavelength. These are directional quantities. The SI unit of radiance is the watt per steradian per square metre (W·sr−1·m−2), while that of spectral radiance in frequency is the watt per steradian per square metre per hertz (W·sr−1·m−2·Hz−1) and that of spectral radiance in wavelength is the watt per steradian per square metre, per metre (W·sr−1·m−3)—commonly the watt per steradian per square metre per nanometre (W·sr−1·m−2·nm−1). The microflick is also used to measure spectral radiance in some fields
[...More...]

"Radiance" on:
Wikipedia
Google
Yahoo

picture info

Velocity
The VELOCITY of an object is the rate of change of its position with respect to a frame of reference , and is a function of time. Velocity is equivalent to a specification of its speed and direction of motion (e.g. 7001600000000000000♠60 km/h to the north). Velocity
Velocity
is an important concept in kinematics , the branch of classical mechanics that describes the motion of bodies. Velocity
Velocity
is a physical vector quantity ; both magnitude and direction are needed to define it. The scalar absolute value (magnitude ) of velocity is called "speed", being a coherent derived unit whose quantity is measured in the SI (metric system ) as metres per second (m/s) or as the SI base unit of (m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object has a changing velocity and is said to be undergoing an acceleration
[...More...]

"Velocity" on:
Wikipedia
Google
Yahoo

picture info

Radius
In classical geometry , a RADIUS
RADIUS
of a circle or sphere is any of the line segments from its center to its perimeter , and in more modern usage, it is also the length of any of them. The name comes from the Latin
Latin
radius, meaning ray but also the spoke of a chariot wheel. The plural of radius can be either radii (from the Latin
Latin
plural) or the conventional English plural radiuses. The typical abbreviation and mathematical variable name for radius is R. By extension, the diameter D is defined as twice the radius: d 2 r r = d 2 . {displaystyle ddoteq 2rquad Rightarrow quad r={frac {d}{2}}.} If an object does not have a center, the term may refer to its CIRCUMRADIUS, the radius of its circumscribed circle or circumscribed sphere . In either case, the radius may be more than half the diameter, which is usually defined as the maximum distance between any two points of the figure
[...More...]

"Radius" on:
Wikipedia
Google
Yahoo

picture info

Surface Area
The SURFACE AREA of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of arc length of one-dimensional curves, or of the surface area for polyhedra (i.e., objects with flat polygonal faces ), for which the surface area is the sum of the areas of its faces. Smooth surfaces, such as a sphere , are assigned surface area using their representation as parametric surfaces . This definition of surface area is based on methods of infinitesimal calculus and involves partial derivatives and double integration . A general definition of surface area was sought by Henri Lebesgue
Henri Lebesgue
and Hermann Minkowski
Hermann Minkowski
at the turn of the twentieth century
[...More...]

"Surface Area" on:
Wikipedia
Google
Yahoo

picture info

Lumen (unit)
The LUMEN (symbol: lm) is the SI derived unit
SI derived unit
of luminous flux , a measure of the total quantity of visible light emitted by a source. Luminous flux differs from power (radiant flux ) in that radiant flux includes all electromagnetic waves emitted, while luminous flux is weighted according to a model (a "luminosity function ") of the human eye 's sensitivity to various wavelengths . Lumens are related to lux in that one lux is one lumen per square meter. The lumen is defined in relation to the candela as 1 lm = 1 cd ⋅ sr . A full sphere has a solid angle of 4π steradians , so a light source that uniformly radiates one candela in all directions has a total luminous flux of 1 cd × 4π sr = 4π cd⋅sr ≈ 12.57 lumens
[...More...]

"Lumen (unit)" on:
Wikipedia
Google
Yahoo

picture info

Circumference
The CIRCUMFERENCE (from Latin circumferentia, meaning "carrying around") of a closed curve or circular object is the linear distance around its edge . The circumference of a circle is of special importance in geometry and trigonometry . Informally "circumference" may also refer to the edge itself rather than to the length of the edge. Circumference
Circumference
is a special case of perimeter : the perimeter is the length around any closed figure, but conventionally "perimeter" is typically used in reference to a polygon while "circumference" typically refers to a continuously differentiable curve
[...More...]

"Circumference" on:
Wikipedia
Google
Yahoo

picture info

Volume
VOLUME is the quantity of three-dimensional space enclosed by a closed surface , for example, the space that a substance (solid , liquid , gas , or plasma ) or shape occupies or contains. Volume
Volume
is often quantified numerically using the SI derived unit
SI derived unit
, the cubic metre . The volume of a container is generally understood to be the capacity of the container, i. e. the amount of fluid (gas or liquid) that the container could hold, rather than the amount of space the container itself displaces. Three dimensional mathematical shapes are also assigned volumes. Volumes of some simple shapes, such as regular, straight-edged, and circular shapes can be easily calculated using arithmetic formulas . Volumes of a complicated shape can be calculated by integral calculus if a formula exists for the shape's boundary
[...More...]

"Volume" on:
Wikipedia
Google
Yahoo

picture info

G-force
The G-FORCE (with g from gravitational) is a measurement of the type of acceleration that causes a perception of weight . Despite the name, it is incorrect to consider g-force a fundamental force, as "g-force" (lower case character) is a type of acceleration that can be measured with an accelerometer . Since g-force accelerations indirectly produce weight, any g-force can be described as a "weight per unit mass" (see the synonym specific weight ). When the g-force acceleration is produced by the surface of one object being pushed by the surface of another object, the reaction-force to this push produces an equal and opposite weight for every unit of an object's mass. The types of forces involved are transmitted through objects by interior mechanical stresses. The g-force acceleration (save for certain electromagnetic force influences) is the cause of an object's acceleration in relation to free-fall
[...More...]

"G-force" on:
Wikipedia
Google
Yahoo

picture info

Minutes Of Arc
A MINUTE OF ARC, ARCMINUTE (arcmin), ARC MINUTE, or MINUTE ARC is a unit of angular measurement equal to 1/60 of one degree . Since one degree is 1/360 of a turn (or complete rotation), one minute of arc is 1/7004216000000000000♠21600 of a turn. A minute of arc is π/7004108000000000000♠10800 of a radian . A SECOND OF ARC, ARCSECOND (arcsec), or ARC SECOND is 1/60 of an arcminute, 1/7003360000000000000♠3600 of a degree, 1/7006129600000000000♠1296000 of a turn, and π/7005648000000000000♠648000 (about 1/7005206265000000000♠206265) of a radian. These units originated in Babylonian astronomy as sexagesimal subdivisions of the degree; they are used in fields that involve very small angles, such as astronomy , optometry , ophthalmology , optics , navigation , land surveying and marksmanship . To express even smaller angles, standard SI prefixes can be employed; the MILLIARCSECOND (mas) and MICROARCSECOND (μas), for instance, are commonly used in astronomy
[...More...]

"Minutes Of Arc" on:
Wikipedia
Google
Yahoo

Surface Gravity
The SURFACE GRAVITY, g, of an astronomical or other object is the gravitational acceleration experienced at its surface. The surface gravity may be thought of as the acceleration due to gravity experienced by a hypothetical test particle which is very close to the object's surface and which, in order not to disturb the system, has negligible mass. Surface gravity is measured in units of acceleration, which, in the SI system, are meters per second squared . It may also be expressed as a multiple of the Earth
Earth
's standard surface gravity , g = 9.80665 m/s². In astrophysics , the surface gravity may be expressed as log g, which is obtained by first expressing the gravity in cgs units , where the unit of acceleration is centimeters per second squared, and then taking the base-10 logarithm . Therefore, the surface gravity of Earth
Earth
could be expressed in cgs units as 980.665 cm/s², with a base-10 logarithm (log g) of 2.992
[...More...]

"Surface Gravity" on:
Wikipedia
Google
Yahoo

picture info

Flattening
FLATTENING is a measure of the compression of a circle or sphere along a diameter to form an ellipse or an ellipsoid of revolution (spheroid ) respectively. Other terms used are ELLIPTICITY, or OBLATENESS. The usual notation for flattening is f and its definition in terms of the semi-axes of the resulting ellipse or ellipsoid is f l a t t e n i n g = f = a b a . {displaystyle mathrm {flattening} =f={frac {a-b}{a}}.} The compression factor is b/a in each case. For the ellipse, this factor is also the aspect ratio of the ellipse. There are two other variants of flattening (see below) and when it is necessary to avoid confusion the above flattening is called the FIRST FLATTENING
[...More...]

"Flattening" on:
Wikipedia
Google
Yahoo

picture info

Luminous Efficacy
LUMINOUS EFFICACY is a measure of how well a light source produces visible light. It is the ratio of luminous flux to power , measured in lumens per watt in the International System of Units (SI). Depending on context, the power can be either the radiant flux of the source's output, or it can be the total power (electric power, chemical energy, or others) consumed by the source. Which sense of the term is intended must usually be inferred from the context, and is sometimes unclear. The former sense is sometimes called LUMINOUS EFFICACY OF RADIATION, and the latter LUMINOUS EFFICACY OF A SOURCE or OVERALL LUMINOUS EFFICACY. Not all wavelengths of light are equally visible, or equally effective at stimulating human vision, due to the spectral sensitivity of the human eye ; radiation in the infrared and ultraviolet parts of the spectrum is useless for illumination
[...More...]

"Luminous Efficacy" on:
Wikipedia
Google
Yahoo

Julian Year (astronomy)
In astronomy , a JULIAN YEAR (symbol: A) is a unit of measurement of time defined as exactly 365.25 days of 7004864000000000000♠86400 SI seconds each. The length of the Julian year is the average length of the year in the Julian calendar that was used in Western societies until some centuries ago , and from which the unit is named. Nevertheless, because astronomical Julian years are measuring duration rather than designating dates, this Julian year does not correspond to years in the Julian calendar or any other calendar. Nor does it correspond to the many other ways of defining a year. CONTENTS * 1 Usage * 2 Epochs * 3 Julian calendar distinguished * 4 Julian day distinguished * 5 References * 6 External links USAGEThe Julian year is not a unit of measurement in the International System of Units (SI), but it is recognized by the International Astronomical Union (IAU) as a non-SI unit for use in astronomy
[...More...]

"Julian Year (astronomy)" on:
Wikipedia
Google
Yahoo
.