Planetary science Reference Libraries

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Mars Moon -- Phobos
2004-10-19 04:45:40

Mars' Moon Phobos -- in astronomy, innermost moon, or natural satellite, of Mars. Phobos orbits Mars at a distance of only 9,378 km (5,627 mi), closer to its planet than any other moon in the solar system. In fact, it is so close that the force of Mars's gravity is stronger than the force keeping the moon in its orbit, so the radius of Phobos's orbit is decreasing at the rate of about 1.8 m...

Earths Moon
2004-10-19 04:45:40

The Moon -- natural satellite of a planet, in particular, the single natural satellite of the earth. The Earth-Moon System The moon is the earth's nearest neighbor in space. In addition to its proximity, the moon is also exceptional in that it is quite massive compared to the earth itself, the ratio of their masses being far larger than the similar ratios of other natural satellites...

Near-Earth Asteroid
2004-10-19 04:45:40

Near-Earth Asteroid -- Near-Earth asteroids (NEAs) are asteroids whose orbit intersects Earth's orbit and which may therefore pose a collision danger, as well as being most easily accessible for spacecraft from Earth. In fact, some near-Earth asteroids can be reached with much less ΔV than the Moon. The most famous near-Earth asteroid is 433 Eros that was visited by NASA's Near Earth...

Brown Dwarf
2004-10-19 04:45:40

Brown Dwarf -- Brown dwarfs are a special type of low-mass star (approximately 13-70 Jupiter masses) that do not have nuclear fusion occurring in their cores during their time on the main sequence. Early in their development most brown dwarf stars do have lithium fusion in their cores, and a lack of lithium is a test for low-mass objects that are suspected of being brown dwarfs. Many brown...

Word of the Day
  • Forsooth! indeed! originally a parenthetical phrase used in repeating the words of another with more or less contempt or disdain.
The word 'quotha' is an alteration of 'quoth he'.