Floating around at the edge of the Solar System are leftovers from its formation. This is the Kuiper Belt, which is composed ...

Here are three myths about the appearance of the planets in the night sky — and how to set your expectations to get the most out of this rare opportunity.

Could a giant planet between Mars and Jupiter have doomed Earth? A new study suggests that small changes would have been ...

An international team led by researchers in Japan and Europe has discovered a new multi-planet system around a Sun-like star, ...

Scientists have identified another possible commonality between Earth and Mars: a solid inner core. Scientists have ...

For a long time, scientists thought the Earth's inner core was a solid ball of metal, sort of like a planet within a planet that sits some 3,000 miles (4,828 kilometers) below the surface.

Inner planets are the four planets closest to the Sun: Mercury, Venus, Earth and Mars. They are collectively characterized by a solid surface and small size relative to the outer gas giants.

Early in our Solar System’s history, bits of icy debris were scattered and then gradually coaxed into a spiral alignment in ...

A new study presents a compelling new model for the formation of super-Earths and mini-Neptunes -- planets that are 1 to 4 times the size of Earth and among the most common in our galaxy. Using ...

A new study of decades worth of seismogram data shows that the surface of Earth’s iron and nickel core is more malleable than scientists thought.