Astronomers have spent years searching for a possible hidden giant planet far beyond Neptune. Unusual orbits among distant ...

A planet-size object that possibly once visited the solar system may have permanently changed our cosmic neighborhood by warping the orbits of the four outer planets, a new study suggests. The ...

Jupiter, Saturn, Uranus and Neptune did not always have their current positions in the solar system. According to the ...

Studying the orbits of thousands of exoplanets shows that large planets tend to have elliptical orbits, while smaller planets tend to have more circular orbits. This split coincides with several other ...

New research suggests the moons of Jupiter and Uranus may hint that our planetary neighborhood once had a third ice giant.

This illustration shows an exoplanet orbiting around two brown dwarfs –– objects bigger than gas-giant planets but too small to be proper stars. ESO/M. Kornmesser Astronomers have discovered a ...

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. When ...