mars.nasa.gov

x6715 TIL Phobos, one of Mars's moons, orbits a mere several thousand kilometers away from Mars's surface. That's so close, you couldn't fit Earth in between Mars and Phobos!
VBnDD TIL that smaller craters on Mars are named after towns with a population of less than 10,000.
16pVX TIL The tallest mountain in our solar system is not on Earth, but rather on Mars. Olympus Mons is approximately 13.6 miles high which is three times the height of Mount Everest (tallest mountain on Earth).