Pluto
Because it is so far from the Sun, astronomers had a hard time measuring Pluto’s size. They finally got it […]
Earth’s Moon
Earth and the Moon are more like a double planet than a planet and a moon. The Moon is quite
Mars’ Moons
Deimos is farther away and moves slowly from east to west. Deimos would look like a small dot of light
Jupiter’s Moons
Io: Fire World Robotic probes may someday provide close-up views of some of the most remarkable vistas in the solar
Saturn’s Moons
Titan: Smog World Surrounded by a thick atmosphere that’s topped by orange smog, and with a landscape that in some
Neptune’s Triton
Triton, the largest satellite of Neptune, orbits in the opposite direction from most moons, suggesting that Neptune captured it in
Comets
For astronomers, though, a comet’s beauty is not just in its appearance, but in its content: A comet is an
Asteroids
But the next year, astronomers found a second object in a similar orbit, then another, and another. Instead of a
Neptune
After the discovery of Uranus in 1781, astronomers had a difficult time accurately describing the planet's orbit. Uranus seemed to