On Wednesday the asteroid Apophis will make its closest approach to the Earth for quite a while. No need to drag out your end of the world kits (carefully tucked away after the Mayan apocalypse failed to eventuate), it will pass at a distance almost a tenth of that to the sun. So not close at all really.
The reason this matters is that there remains a small but real possibility that Apophis could be on a collision course for the Earth in 2036. Detailed information about its orbit collected this time may rule out such an event, or suggest the chances are high enough we need to take action.
Apophis is not large enough to wreck destruction on the scale of the “dinosaur killer”, but it could be pretty nasty if it landed on your city. In the more likely event it hit the ocean you’d want to be inland. Well inland.
One good thing about this particular asteroid is it will make a very close approach years before. This 2029 approach is the main reason for its fame, as for a while what we knew of its orbit suggested there was an almost 3% chance of a collision on April 13 (yes, a Friday). Extra data ruled that out, but left the 2036, and some later close encounters, as open possibilities for a close encounter of the unfortunate kind. The 2029 event will not only give an impressive view to those living around the North Atlantic, it will also provide an opportunity for us to send up space ships to either study Apophis, or persuade it to change orbits if the danger from subsequent events looks substantial.
I’ve got a particular interest in this little pile of space rock because one of “my” scientists, Mary D’Souza, won a prize for coming up with the most innovative and practical idea on how to change Apophis’ orbit should we discover this is required. Not a bad achievement for a PhD student, as she was at the time. But if you want to know her idea you’ll have to read the book.