Meet Tylos: a gas giant 900 light years away and with a climate never seen before on any planet known to scientists.

With each mass, she modeled 2 million years of orbit to find what kind of architectural impact each mass would have on our solar system. Specifically, she tracked changes to the other planets ...

The eight planets in our solar system orbit the sun in roughly the same plane, because they all originally formed from the same disc of debris around the sun. The line the sun traces across the ...

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 still be nine if some astronomers are ...

Clyde Tombaugh discovered Pluto in 1930 at Lowell Observatory in Flagstaff. Here's how Pluto won - and lost - its planetary status.

They emerge from the farthest reaches of the solar system, way beyond the orbit of Neptune, then zip past the sun before disappearing again for centuries. Due to their irregular shapes and small ...