Does our Solar System have 9 planets or only 8? Astronomers have gone back and forth on that a lot, with Pluto now being classified as a dwarf planet. However, out beyond Neptune there could be ...

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.

Scientists believe that two asteroids might be fragments of long-lost "planetary embryos" from the early solar system.

Gaia-4b is considered a super-Jupiter planet, a relatively cold gas giant, orbiting its star over 570 Earth-days. That star ...

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 of Jupiter may have flown through our ...

Filmmaker Adam Nemoy helps celebrate the 90th anniversary of Pluto's discovery this month at the 6th annual 'I Heart Pluto' ...

All of our solar system’s planets are lining up to parade through the night sky at once. This extraordinary celestial event will see the sky scattered with seven visible planets in what is known ...

In August 2006, the International Astronomical Union made the controversial, but correct, decision to demote Pluto from its ...

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.

Timing: Dusk after sunset, but before 9 p.m. local time There are eight planets in our solar system and one dwarf planet (Pluto). Because we live on Earth, the most we could see is a maximum of seven ...

Timing: Dusk after sunset, but before 9 p.m. local time There are eight planets in our solar system and one dwarf planet (Pluto). Because we live on Earth, the most we could see is a maximum of ...