RL = 2.456*R*(p'/p)^(1/3)
where p' is the density of the planet, p is the density of the moon, and R is the radius of the planet. (more)
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the orbital radius at which the satellite's orbital period is equal to the rotational period of the planet. A synchronous satellite with an orbital inclination of zero (same plane as the planet's equator) stays fixed in the sky from the perspective of an observer on the planet's surface (such orbits are commonly used for communications satellites).
said of a satellite if the period of its rotation about its axis is the same as the period of its orbit around its primary. This implies that the satellite always keeps the same hemisphere facing its primary (e.g. the Moon). It also implies that one hemisphere (the leading hemisphere) always faces in the direction of the satellite's motion while the other (trailing) one always faces backward. Most of the satellites in the solar system rotate synchronously.
deformation forces acting on a planet's crust.
the dividing line between the illuminated and the unilluminated part of the moon's or a planet's disk.
extensive land mass.
tile; terrain formed of polygonal pattern.
small domical mountain or hill.
aka Lord Kelvin, British physicist who developed the Kelvin scale of temperature. Also supervised the laying of a trans-Atlantic cable. (10k gif)
frictional heating of a satellite's interior due to flexure caused by the gravitational pull of its parent planet and possibly neighboring satellites.
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an object orbiting in the Lagrange points of another (larger) object. This name derives from a generalization of the names of two of the largest asteroids in Jupiter's Lagrange points: 624 Hektor and 911 Agamemmnon. Saturn's satellites Helene, Calypso and Telesto are also sometimes called Trojans.
the dark central region of a sunspot.
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American physicist who discovered the Earth's radiation belts (that now bear his name) with an instrument aboard the first successful American satellite, Explorer 1.
French writer who is considered the founder of modern science fiction. His novels include "Journey to the Center of the Earth" and "From the Earth to the Moon".
a whitish star of high surface temperature and low intrinsic brightness with a mass approximately equal to that of a Sun but with a density many times larger.