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

At half the size of Earth and one-tenth its mass, Mars is a featherweight as far as planets go. Yet new research reveals the ...

Astronomers have captured an exceptionally rare view of young planets in mid-transformation, revealing how bloated, giant worlds may shrink into the most common planets in the galaxy. Astronomers have ...

A has been around since the Chernobyl explosion and Space Shuttle Challenger accident...but perhaps not for much longer.