Does our Solar System have 9 planets or only 8? Astronomers have gone back and forth on that a lot, with Pluto now being classified as a dwarf planet. However, out beyond Neptune there could be ...

Scientists believe that two asteroids might be fragments of long-lost "planetary embryos" from the early solar system.

Stargazers will be treated to a rare seven-planet alignment in February. This is what scientists hope to learn.

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 ...

Stargazers will be treated to a rare alignment of seven planets on 28 February when Mercury joins six other planets that are already visible in the night sky. Here's why it matters to scientists.

This may explain the strange properties of the orbits of our solar system's planets, which are not quite perfectly circular, and all lie on slightly different planes. NASA artist’s conception of ...

17 and 18. Timing: Dusk after sunset, but before 9 p.m. local time There are eight planets in our solar system and one dwarf planet (Pluto). Because we live on Earth, the most we could see is a ...