The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

ISTOCK / GETTY IMAGES PLUS The planets in our solar system orbit the sun in roughly the same plane, known as the ecliptic, which is tilted relative to Earth's equator by about 23.5 degrees.

"Relatively small planets similar to the size of Earth are ... There are nearly 300 moons in our solar system, but their masses are typically much smaller relative to their host planets than ...

A planet-size object that possibly once visited the solar system may have permanently changed our cosmic neighborhood by warping the orbits of the four outer planets, a new study suggests.

Keep your eyes on the sky. Six planets in our solar system are coming into alignment and will be visible from Earth. AccuWeather says Saturn, Venus, Neptune, Uranus, Jupiter and Mars will be ...

Despite common assumptions, the disk of our Solar System is warped, and the planets travel around the Sun in slightly eccentric (or oblong) orbits. Scientists now think that a mysterious object ...

All of our solar system’s planets are lining up to parade through the night sky at once. This extraordinary celestial event will see the sky scattered with seven visible planets in what is known ...