The catalog of known worlds beyond our solar system has crossed another threshold. NASA’s official tally now exceeds 6,000 ...

We usually think of our solar system as a calm, well-organized family of planets, but a new study suggests its early days may ...

At the right point of the orbit and stellar cycle, the star’s chromosphere brightens.

The hunt for Planet Nine continues as new discoveries make the Solar System’s biggest mystery even harder to solve. Is there ...

The workings of our solar system are roughly the same now as they have been for millions of years. Moons circle their planets, the planets circle the sun, the sun’s magnetic fields and ...

Illustration comparing the planets of the Solar System and the Sun on the same scale. The planets are shown to scale relative to each other but their distances are not. From left to right the ...

Mark Sykes says that if a non-stellar object is massive enough to be round and orbits a star, it ought to be a planet. The key here is that once an object gets that big, important geophysical ...

Venus, Jupiter and Mercury are due to form a planet parade in June visible across the US. What to know, including the date and time and where to look.