Researchers studying decades of earthquake data say they have found the first evidence that, in addition to spinning backward ...

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

and elemental ratios that indicate they could only have formed in the inner solar system. "Angrites are a small group of ancient meteorites that formed within the first few million years of solar ...

In these simulations, the orbits were warped by the passing of an object between two and 50 times Jupiter's mass, which plunged deep into the inner solar system as it traveled. "This [mass] range ...

Mars's moon Phobos is so strange that no one knows how it formed. But a forthcoming mission could solve this mystery - and a host of other puzzles connected to the solar system's deep past ...