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 ...

Though the planets are always “aligned,” seeing more than four in the sky is more uncommon. February’s lineup is a chance to ...

Both systems include a moon that is a large fraction of the size of the main body, unlike other moons in the solar system ... while the moons of the giant planets make up a small fraction of ...

15, 2025 — New observational data and simulation models have confirmed a new type of planet ... the Earth-Moon system. Both systems include a moon that is a large fraction of the size ...

Researchers accounted for the previously overlooked structures of the dwarf planet and moon in computer simulations of a ...

From January to March, the night sky will host a spectacular parade of planets featuring Venus, Mars, Jupiter, Saturn, Uranus ...

An asteroid that orbited near Earth for a few months as a mini-moon may be a chunk of the moon that was blasted off by an ...

But how well do you really know our planetary neighbor? This quiz of 15 questions will test your knowledge of Mars' size, surface and history, as well as scientists' attempts to study it. Remember to ...

Plate tectonics give Earth its mountains, earthquakes, continental drift and maybe even helped give rise to life itself. But ...