Learn what planet rains molten iron and which planet has two moons like Tatooine in Star Wars.

The finding points toward two different pathways by which large and small planets form. "What we found is that right around the size of Neptune, planets go from being almost always on circular ...

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.

Once the planets meet, it looks as though they are aligned as they path Earth, but the line will not be perfectly straight, according to Space.com. With each planet moving at different speeds ...

The planets in the solar system orbit the sun, just as Earth does. Every planet orbits at a different speed and distance. During these alignments, the planets appear to be lined up from Earth's ...