Which way is ‘down’ has a different answer depending on where you are on Earth, in the solar system, in our galaxy and beyond ...

Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously ...

Over the next several nights in the Philadelphia region, through its peak on Friday, we will have the opportunity to see all seven of our sister planets simultaneously and in a straight line, parading ...

Planet Y is the latest in a series of hypothetical solar system planets that scientists have proposed in recent years, all with slightly different characteristics but collectively believed to be ...

Studying the orbits of thousands of exoplanets shows that large planets tend to have elliptical orbits, while smaller planets tend to have more circular orbits. This split coincides with several other ...