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

Mars, Venus, Jupiter and Saturn should be visible to the naked eye, but with a telescope you can spot Neptune and Uranus.

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

For this, astronomers used two facilities: the Submillimeter Array (SMA), CfA's eight-dish collection of radio telescopes in ...

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.

A U.S. scientist searching for a civilization across 7 Earth clones circling the red dwarf star TRAPPIST-1 says its own alien astronomers could also be scanning Earth.

Starting up again Saturday, a sweeping view of our solar system will glow in the night sky. The planetary alignment, or a ...