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

The formation of our solar system from a singular nebula raises an intriguing question: why did each planet develop with a ...

While the composition of gas and dust in a molecular cloud is fairly uniform, everything changes once a star begins to form.

An object eight times the mass of Jupiter may have swooped around the sun, coming superclose to Mars' present-day orbit ...

HD 20794 d completes its orbit just shy of two Earth years, placing it well within reach of conditions that might harbor life ...

For much of January and February, you have the chance to see six planets in our solar system after dark, although two — Uranus and Neptune — will be hard to see without a telescope or high-powered ...

On Feb. 24, from west to east, you can see Mercury, Saturn, Neptune, Venus, Uranus, Jupiter and Mars, all spanning 117.5°, ...

The Romans had different names for the Greek gods, and so they were the ones to eventually call it Mars. Jupiter is the biggest planet in our Solar System, and it gets its name from the leader of ...

When astronomers found a large world farther out than Pluto, it became one of the final nails in the coffin of our ninth ...

Aside from Earth, no planet in the solar system captures our imagination quite like Mars. The Red Planet is one of the few ...

In fact, they even went so far to give it a name, Planet 9. Now, of course, if they were to confirm this discovery, it would be groundbreaking. The first new planet in our solar system since the ...