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

Saturn, Venus, Neptune, Uranus, Jupiter, Mars and Mercury will be visible in an uncommon planetary alignment this month.

Pluto may not be a planet any more, but you still have a chance to see the distant dwarf planet at one of Michigan's ...

The dwarf planet ... reached the inner Solar System only later. For the current study, the researchers looked for previously unknown deposits of organic material on dwarf planet Ceres.

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.

The organic material found in a few areas on the surface of dwarf planet Ceres is probably of ... conditions could have arisen in the solar system. Organic molecules are among the necessary ...

Predictions are uncertain, but the solar system may be pushed farther from the galactic core or even ejected entirely from ...

"With an orbital period of 570 days, it is a relatively cold gas giant planet," said Guðmundur Stefánsson of the University of Amsterdam in a statement. This orbital period places it a little closer ...

For decades, Pluto was celebrated as the ninth planet of our solar system. However ... leading to Pluto’s reclassification as a dwarf planet. This decision sparked widespread debate among ...

Ever since Isaac Newton famously talked about gravity, its dominance as a force in our solar system has been well known. It's responsible for the orbits of the planets and their satellites ...

Clyde Tombaugh didn't set out to discover Pluto when he sent his sketches of the night sky to Lowell Observatory in Flagstaff ...

And red dwarf ... star where a planet with an atmosphere could retain liquid water on its surface. Wolk modeled atmospheric conditions similar to those of planets in our solar system, including ...