Mercury

If you ever go to Mercury, bring your sunscreen because it is the planet closest to the Sun. You'll also need a pair of thermal underwear because at night Mercury cools down fast. Temperatures can drop to as low as -292 degrees F! Now that's cold! You will also need a pair of hiking boots so you can travel and climb in and out of the craters that cover Mercury's scarred landscape.

Image credits: main image, courtesy of NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington; quote, © AMNH.