If you get the question in Trivial Pursuit “how many plantes are there in the Solar System?”, depending on when you went to school or how old the version is, there’s a fair chance of giving ...

The way people think of the Solar System has changed many times throughout history. Before the development of the telescope, these ideas were based on what could be seen with the naked eye.

Understanding how the habitability of our solar system's inner planets—Mercury, Venus, Earth and Mars—would change had there been a super-Earth opposite Mars can help guide astrobiologists ...

There may be an undiscovered planet in the outer solar system whose presence is revealed by the strange orbit of objects beyond the eighth planet Neptune. The tantalizing prospect of a ninth ...

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.