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

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

Though the planets are always “aligned,” seeing more than four in the sky is more uncommon. February’s lineup is a chance to ...

Here’s what you should know when you go outside to see for yourself: Yes, the planets are indeed lined up across our sky. No, ...

Beyond Neptune lies the Kuiper Belt, a vast expanse of icy bodies that may hold clues to the solar system’s formation. These ...

An object eight times the mass of Jupiter may have swooped around the sun, coming superclose to Mars' present-day orbit ...

A new study claims it is possible an "alien visitor" could have warped our solar system during its earliest years.

Spotting one or two of the planets in our solar system is well worth a good skywatch, but seeing (almost) all of them in a ...

A super-Earth planet that dips in and out of its star's habitable zone has been discovered just 19.7 light-years away.

Ever since Isaac Newton famously talked about gravity, its dominance as a force in our solar system has been well known. It's ...

The exoplanet – a planet outside our solar system – has a mass six times greater than that of Earth, and orbits in the ...