Investigating the earliest and least known phases of the history of the Solar System, when the young Sun was still enveloped by the disk of gas and dust where its planets began to form, is probably ...

Over the past 250 years, the number of "planets" in our solar system has ranged from six to nine — and, briefly, even 11 — depending on what astronomers knew at the time and how they defined a planet.

What are the weirdest worlds in our solar system, and how did they come to be? From a dwarf planet that looks like a deflated football, to a tiny moon with cliffs taller than Mt. Everest, to the ...

From meteorites that impact Earth, to a moon that orbits backwards, to an imposter lurking in the asteroid belt, a variety of strange, wandering worlds are rewriting what we know – and even how we ...