Happy Cosmonauts Day! Fifty-two years ago today, on April 12, 1961, Yury Gagarin became the first person to travel into space. Here's how he described being in space for the first time: "The feeling of weightlessness is somewhat unfamiliar compared with Earth conditions. Here you feel like you are hanging in a horizontal position in straps. You feel like you are suspended."
Read our related story about Russia's plans to send a mouse into a new level of orbit here.