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 before shoving four of the solar system's planets onto a different course.

All seven of the other planets in our solar system are about to become visible at once in a great planetary alignment – ...

Four planets will be widely visible to the naked eye through part of February, but calling them a 'planetary alignment' may ...

The four-planet lineup that began in January concludes by mid- to late February, as Saturn sinks increasingly lower in the ...