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

The Sun makes up 99% of all the mass in the Solar System ... At 4.5 billion km from the Sun, it receives very little heat and so has an average temperature of just -200°C. While planets and ...

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 ...

All of our solar system ... when the planets appear in the sky, they all appear roughly along the ecliptic. It isn't a perfect line of planets, because their orbits are tilted slightly, but it is ...

and all lie on slightly different planes. 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 ...

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

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 ...