Orbits, and Orbital Decay (Astronomy: Week of 1/21/18)

In case you haven't heard, China's first space station, Tiangong-1 is about to make an uncontrolled re-entry into Earth's atmosphere.  That's an 18,750 pound (8,500 kg) chunk of stuff, about to fall in a blaze of glory.  We don't know when, and we don't know where.... but probably some time in March, 2018. To understand…Read more Orbits, and Orbital Decay (Astronomy: Week of 1/21/18)