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

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

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

While this parade of planets look to our eyes to be huddled in the evening sky, they are of course spread out across a vast chasm of space across the solar system, separated from each other by ...

But because planets always appear in a line from our Earth-bound vantage, the alignment isn't anything out of the norm ... The planets in our solar system orbit the sun essentially along a ...

This may explain the strange properties of the orbits of our solar system's planets, which are not quite ... astrophysics has long been to figure out how the orbits later became out-of-round ...

A rare parade of planets will light up the night sky throughout January. Six planets will be in alignment for the rest of the month – four of which will be visible with the naked eye, Preston Dyches, ...

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.

Most of the information we have about planets beyond our solar system (exoplanets ... as it will seem to block out more of the star's light, or they might infer the planet is hotter than it ...

While the composition of gas and dust in a molecular cloud is fairly uniform, everything changes once a star begins to form.