In this special #deSTEMber Hangout, we visited - quite literally - one of the "coolest" parts of CERN. In the CERN cryogenics laboratory, experts work with liquid nitrogen and liquid helium to cool CERN equipment to temperatures as low as -271°C (about -456°F or 2.15 Kelvin). This temperature is even colder than outer space! In this hangout, our experts performed hands-on experiments to show the weird and wonderful world of liquid nitrogen, and explain why we need to keep parts of CERN so cold.