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1. a celestial body orbiting around a planet or star
2. a man-made device orbiting around the earth, moon, or another planet transmitting to earth scientific information or used for communication
3. a country or political unit under the domination of a foreign power
4. a subordinate area or community that is dependent upon a larger adjacent town or city
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005


Collins Dictionary of Sociology, 3rd ed. © HarperCollins Publishers 2000


(religion, spiritualism, and occult)

A satellite is any body that orbits another body. The body being orbited is referred to as the primary. The most familiar examples of satellites are the Moon, a satellite of Earth, and Earth, a satellite of the Sun. This term was originally used to refer to attendants of important people. It was first applied to celestial bodies by Johannes Kepler, who used the term satellite to refer to the moons of Jupiter.

The Astrology Book, Second Edition © 2003 Visible Ink Press®. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



in astronomy, a body of the solar system that revolves about a planet under the action of the planet’s gravitational attraction. The four brightest satellites of Jupiter—lo, Europa, Ganymede, and Callisto—were, aside from the earth’s moon, the first satellites to be observed. They were discovered by Galileo in 1610. By 1975, 33 satellites of the planets were known: one, the moon, of the earth, two of Mars, 13 of Jupiter, ten of Saturn, five of Uranus, and two of Neptune.

Satellites travel within the gravitational fields of the planets in orbits that differ only slightly in shape from ellipses. The deviations of the actual orbits from elliptical orbits are a result of perturbations caused by the sun’s attraction and by the deviation of the planets’ shapes from a spherical shape. The perturbations that satellites introduce into each other’s orbits can be used to determine the masses of the satellites. The orbital motion of most satellites is direct. In other words, the satellite revolves about the planet in the same direction that the planet revolves about the sun—that is, in a counterclockwise direction when viewed from the north pole of the ecliptic. The only satellites to have retrograde orbits are the satellites VIII, IX, XI, and XII of Jupiter, Saturn’s satellite Phoebe, Uranus’ satellites, and Neptune’s satellite Triton. Table 1 gives the principal data on the known satellites of the planets.

The satellites Phobos and Deimos of Mars are remarkable for their proximity to the planet and their rapid motion. The inner satellite, Phobos, revolves about Mars faster than Mars rotates on its axis, so that an observer on the Martian surface would see the satellite rise in the west and set in the east. Phobos rises and sets twice in a Martian day. Deimos moves across the sky more slowly: more than 2½ days pass between the time the satellite rises above the horizon and the time it sets. Both satellites move almost exactly in the equatorial plane of Mars. In 1972 the Mariner 9 space probe took close photographs of Phobos and Deimos. Both satellites proved to be irregular in shape. Phobos’ dimensions are 27 km × 21 km × 19 km, and those of Deimos are 15 km × 12 km × 11 km; the measurement error here is 0.5–3 km. The geometrical albedo of the Martian satellites does not exceed 0.05—that is, in terms of reflectivity they are comparable to the darkest parts of the lunar maria. Phobos and Deimos are covered with many craters. One crater on Phobos has a diameter of approximately 5.3 km. The craters were undoubtedly formed by impacts.

The four largest satellites of Jupiter—that is, the satellites discovered by Galileo—are comparatively bright objects of the fifth and sixth magnitude. Their orbits are almost circular, and the

Table 1. Satellites of the planets (1975 data)
PlanetSatelliteMean distance from planet (thousands of km)Sidereal period of revolution (days)EccentricityInclination of orbit to planet’s equatorial plane (degrees)Diameter (km)Mass (mass of moon = 1)Year of discovery
 l lo4221.80.0000.03,6400.991610
 I I Europa6713.60.0000.03,1000.641610
 III Ganymede1,0707.20.0010.05,2702.111610
 IV Callisto 1,88016.70.0070.05,0001.321610
 I X23,7007550.28153201914

planes of their orbits approximately coincide with the plane of the planet’s equator. The first determination of the speed of light was made in 1676 on the basis of observations of the eclipses of these satellites. Ganymede and Callisto are larger than the planet Mercury. For each of the four satellites, the period of rotation is the same as the period of revolution about Jupiter. Consequently, each satellite always presents the same side to the planet. A considerable part of the surfaces of Europa and Ganymede is covered with ice. The Pioneer 10 spacecraft discovered in 1973 that Io has a dense atmosphere. Jupiter’s satellite XIII was discovered in October 1974.

Saturn’s satellite Titan is larger than Mercury. Titan has an atmosphere, which, like the atmosphere of Saturn, contains methane and ammonia. The closest satellite to the planet, Janus, was discovered on Dec. 15,1966, when Saturn’s rings were invisible. This satellite is usually concealed in the halo of the brilliant rings.

The orbital planes of the satellites of Uranus are close to the equatorial plane of the planet. The satellites revolve in the same direction as Uranus rotates. Since, however, the equatorial plane of the planet is tilted at an angle of 98° to the plane of the planet’s orbit, Uranus moves with its satellites as if it were lying on its side.

Neptune’s satellite Triton was discovered in 1846, two weeks after the discovery of the planet. Triton is larger in size and greater in mass than the moon. The other satellite, Nereid, has a highly eccentric orbit. As a result, its distance from the planet varies from 1.5 to 9.6 million km.

Most of the names of the satellites were taken from ancient mythology and works of literature. The satellites of Jupiter discovered by Galileo are also designated by the Roman numerals I, II, III, and IV, in order of increasing distance from Jupiter. Jupiter’s remaining satellites, which were discovered later, are designated by Roman numerals in the chronological order of the satellites’ discovery.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

What does it mean when you dream about a satellite?

A dream about a satellite is most likely about communication, particularly at a global level. Alternatively, a satellite is something that is trapped by the gravitational pull of another heavenly body.

The Dream Encyclopedia, Second Edition © 2009 Visible Ink Press®. All rights reserved.


(aerospace engineering)
A small, solid body moving in an orbit around a planet; the moon is a satellite of earth.
(cell and molecular biology)
A chromosome segment distant from but attached to the rest of the chromosome by an achromatic filament.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

communications satellite

A radio relay station in orbit above the earth that receives, amplifies and redirects analog and digital signals contained within a carrier frequency. Based on their distance from the earth, there are three categories: GEO, LEO and MEO.

Geostationary (GEO) satellites are in orbit 22,282 miles above the earth. Because they rotate with the earth, they appear motionless to an observer on the ground. The GEO downlink to earth can be localized into small areas or cover as much as a third of the globe's surface. Low-earth orbit (LEO) and medium-earth orbit (MEO) satellites are much closer to the ground, and they revolve around the planet. See GEO, LEO and MEO.

Fixed and Mobile Satellite Services (FSS/MSS)
Delivery from a communications satellite may be to stationary terminals such as rooftop dishes (see FSS) or to mobile terminals in cars, planes and ships (see MSS). See satellite Internet, satellite frequency bands and bent pipe architecture.

Communications Satellite
There are hundreds of commercial communications satellites in orbit providing private channels between business and government facilities as well as access to the Internet for the general public (see satellite Internet).
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References in periodicals archive ?
Although this issue of space debris has not been discussed much so far, since there would be conflicts of interest among nations and also enormous costs in cleaning it up (almost corresponding to the cost of launching an artificial satellite), it is now gradually being discussed among nations.
Renzetti, "History of the attempts to measure orbital frame-dragging with artificial satellites," Central European Journal of Physics, vol.
* What powers artificial satellites? (batteries, the sun, etc.)
The first artificial satellite, Sputnik 1, was launched by the Soviet Union in 1957.
This was the first important discovery-an entirely unexpected one-to be made as a result of the launching of artificial satellites.
Davis, director of the Arecibo Radio Observatory in Puerto Rico, will work on configuring the project's radio receivers to automatically weed out spurious signals from Earth or nearby, including those from artificial satellites.
How many artificial satellites orbited the Earth as of 2011: 665; 13; 931; 93?
This app for Apple and Android mobile devices shows you the positions of hundreds of artificial satellites in real time.
The inducement was even held out of the Observatory acquiring the camera at the end of the IGY and using it for purely astronomical purposes, (as I once remarked at a meeting of the Satellite Committee, the belief seemed to be prevalent that all artificial satellites would obediently tumble to Earth on 31 December 1958--failure to realize that we were witnessing the birth of a new era.) I insisted that the proposal would be acceptable only on condition that the camera station had its own Officer-in -Charge as a branch of the Observatory, recruited its own staff, and in the event of unfillable vacancies, would not be allowed to call on the observatory's astronomical specialists.
On any clear night, a dozen or so artificial satellites can be seen moving slowly across the sky.
First, TV stations send signals in the form of light waves to artificial satellites. Then, these human-made devices circling above Earth transmit the signals to satellite dishes all over the world-giving people like this woman in Anhui a clear view of her favorite TV program.