Mankind has always been fascinated by science and discovery. In his search, he has been able to launch thousands of satellites into space, not only for research but also for communiction. Communication, as we know it today is very similar to the first satellite sent into space, Sputnik 1. Launched on 4 October 1957, it transmitted a pulse which ham radio operators (a.k.a: amateur radio) could pick up on their radios. Today, a similar kind of system is in use: satellites transmit radio waves which are picked up by antennas on earth, the information is then processed to be understandable by humans.
With a ham receiver we can listen to local or international (via satellite or the Internationnal Space Station) ham radio conversations or hear cube satellites (a.k.a: cubesats) transmitting their ID in morse code. Many websites allow you to track satellites such as the ISS. And sometimes, you might even be able to talk to an astronaut!