Astronauts are hand-picked among tens of thousands of other candidates to travel into space. So you might think that once they went through all of this, they don’t have anything left to prove to anyone… And yet…

Since the early 20th century, the International Astronomical Union or IAU – an organization that brings together astronomers from around the world – defines the names used by astronomers to talk about objects in the Solar System. In August 2006, the IAU decided a planet is an object that

The pavement requires frequent renewal of the top surface. The frequency depends on the type of pavement and on the weather. Asphalt for instance suffers a lot of damage when it snows and becomes less viscous when it is very hot, causing heavy aircraft to sink.