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 ...

When I was a kid, there were nine planets. Now we know of thousands! But that includes exoplanets, alien worlds that orbit alien suns. Only eight planets call our solar system home. Or there might ...

For many years scientists have been wondering if a mysterious ninth planet lurks in our Solar system. “Planet Nine”, dubbed, has fascinated scientists for its ability to account for “anomalous” ...

The Planet Nine theory was based on several trans-Neptunian ... This seemed odd and illogical as when the Solar system formed, it would be expected that objects that developed in the circumstellar ...

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 ...

This may explain the strange properties of the orbits of our solar system's planets, which are not quite perfectly circular, and all lie on slightly different planes. NASA artist’s conception of ...

When to look: Mid and late January, but best visibility may be the night of Jan. 17 and 18. Timing: Dusk after sunset, but before 9 p.m. local time There are eight planets in our solar system and one ...