Without GPS, we’d be lost. Literally. Thanks to these radio transmissions from space though, we’re able to pinpoint our location and find our way home. Join us as we learn all about satellites, how the robot voice of GPS is created and how atomic clocks hold it all together. Plus a mystery sound and a brand new Moment of Um answers the question: "What is light made of?" Today's episode is sponsored by Kind Snacks (KindSnacks.com/BRAINS), Vamousse (vamousselice.com) and Roshambo Baby (roshambobaby.com and offer code BRAINS).See omnystudio.com/listener for privacy information.