Which way is ‘down’ has a different answer depending on where you are on Earth, in the solar system, in our galaxy and beyond ...

Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously unknown world may be lurking in the outer reaches of the solar system. The ...

When you buy through links on our articles, Future and its syndication partners may earn a commission. A composite image comparing the relative sizes of our solar system's known dwarf planets, ...

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 ...

Discovered by volunteer scientists, this alien planet is out of synch with its siblings ...

China advances plans for dual solar system boundary missions China has published coordinated papers outlining dual missions ...

The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper’s authors have dubbed ...

The Sun is an incandescent but benevolent dictator. For billions of years, it’s kept our star system well organized through the influence of its powerful gravity. All the planets revolve around it on ...

Planet Y is the latest in a series of hypothetical solar system planets that scientists have proposed in recent years, all with slightly different characteristics but collectively believed to be ...