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

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

All of our solar system’s planets are lining up to parade through the night sky at once. This extraordinary celestial event ...

Mercury is the closest planet to the sun, followed by Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Mercury orbits ...

Staring up at the night sky, you might see thousands of stars sprinkled above the horizon. It feels as though you can see so ...

Beyond Neptune lies the Kuiper Belt, a vast expanse of icy bodies that may hold clues to the solar system’s formation. These ...

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

Six of our cosmic neighbors are expected to line up across the night sky tonight, in what has been dubbed a "planetary parade ...

Starting up again Saturday, a sweeping view of our solar system will glow in the night sky. The planetary alignment, or a ...

The enormous visitor to our solar system may have been about 8 times the mass of Jupiter, and come nearly as close to the sun ...

Baker said that there are other astronomical events that may be more interesting than the parade of planets. Baker said Mars ...

When you first learned about the Solar System, you probably saw diagrams that made it look orderly, with planets arranged in ...