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

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 ...

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

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 ...

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.