See how John Glenn's Mercury mission put the first American in orbit in 1962 in this SPACE.com infographic.
Astronomers have discovered a large valley on Mercury that provides further evidence for the planet's shrinkage — an odd phenomenon that has been the topic of debate for decades.
Mercury may still rumble with earthquakes, or "mercuryquakes," according to evidence found in cliffs on the planet's surface.
Mercury has a reputation for being hard to spot. But skywatchers have a great chance to see the small, fast-moving planet this month.
A rare type of meteorite found on Earth may have been a critical ingredient in the geologic recipe that shaped the surface of Mercury, new research shows.
With a little bit of patience — and luck — you'll be able to glimpse the five brightest naked-eye planets during this month.