Like its Roman-god namesake, Mercury is known for extreme behavior.
Scientists recently discovered Earth‑sized planets orbiting a star more than 11 billion years old.
Extrasolar planets form along misaligned orbits.
Astronomers made a big discovery in determining Pluto's dwarf planet credentials.
Canadian scientists studying water found deep in an underground mine have determined that the water is at least 1.5 billion years old, and maybe much older.
Scientists have a new estimate for the geological age of one of Mercury's oldest regions.
One of the great mysteries: Does life exist elsewhere in the universe. Research has found that such planets may be more common, and much closer, than we think.
Did you know it seems we're discovering a new exoplanet every week?
A Moment of Science looks at the many different moons in our solar system.
So, if the planet doesn't orbit a sun, can it still be called a planet?