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

Stargazers will be treated to a rare seven-planet alignment in February. This is what scientists hope to learn.

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 ...

and all lie on slightly different planes. NASA artist’s conception of a brown dwarf (main) and stock image of the planets in the solar system (inset). An object between 2 and 50 times the mass ...

That’s because Pluto was downgraded from a “planet” to a “dwarf planet ... could prove once and for all that there really is a ninth planet in our Solar System. The same year that ...

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.

turning this into a planetary parade of all seven planets in our solar system other than Earth. It will be difficult to see them all since Saturn, Mercury and Neptune will be quite close to the ...