21: BepiColombo goes to Mercury

Mercury: closest planet to the Sun, a small, uninteresting lump of rock ... or, an enigma, with a strange tidally-locked orbit, a core that's way too big, and a mysterious origin story that astronomers are slowly piecing together. Which is why it's Emily's favourite planet, and why ESA and JAXA are sending the fabulously-named BepiColombo spacecraft to take a closer look.