I'm @pa1ejo on twitter and in my free time I blog on climate change, spaceflight and topics of general scientific interest. In real life you'll find me at the Delft University of Technology, we run courses on planetary sciences and physics of the Earth. That boot in my profile picture was left one of the Apollo astronauts in the lunar dust, now almost 50 years ago. It will remain there until dust caused by meteorite impacts on the moon has covered it up. Once it has I wonder whether there are still humans left on Earth, because the general mood so far has been: 'apres nous le deluge'. We are also good at covering things up.