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

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

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 ...

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 ...

Uranus and Neptune are there too, technically, but they don't appear as 'bright planets'," NASA's Preston Dyches explained in a stargazing video guide. Stock illustration of all the solar system's ...

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

A planet parade is when several of our solar system's planets are visible in the night sky at the same time. There will be six planets visible this time around, including Venus, Mars, Jupiter ...

However, this year a powerful new telescope is coming online that could prove once and for all that there really is a ninth planet in our Solar System. The same year that Pluto was ignominiously ...