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

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 ...

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 ...

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

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 ...

To better understand why the planets have variable compositions ... to the formation of the gas and ice giants in the outer solar system. This first-order model of planetary growth in the solar ...

An object eight times the mass of Jupiter may have swooped around the sun, coming superclose to Mars' present-day orbit before shoving four of the solar system's planets onto a different course.

All seven of the other planets in our solar system are about to become visible at once in a great planetary alignment – here’s how to spot the celestial show ...