You may have heard a lot of online chatter about Earth's two moons recently, but that doesn't quite get the discovery right. Earth still only has one true natural satellite — our 2,159-mile-wide moon ...

Exoplanets are planets outside Earth's solar system. In 1995, a gas giant named 51 Pegasi b, which orbits a star similar to Earth's sun, etched its name in history as the first exoplanet ever ...

Could there be an even better planet for us than Earth? Scientists are searching for a superhabitable world that wouldn’t ...

Researchers have discovered chemical fingerprints of Earth's earliest incarnation, preserved in ancient mantle rocks. A unique imbalance in potassium isotopes points to remnants of “proto Earth” ...