Cosmic Impacts
Contact: John Davies
I study Near Earth Objects, small(ish) objects which cross the orbit of the Earth and which present a danger to life on Earth. An NEO impact was probably what killed the dinosaurs about 65 million years ago and similar collisions still occur from time to time. Finding out the sizes of these objects is quite difficult since they tend to be irregular (potato shaped) and we don't know how reflective they are. This means that you can't really tell if you are looking at a large dark object (like a sack of coal) or a small white object (like a snowball). We observe simultaneously in visible light and in the infrared since the ratio of the reflected (visible) and emitted (infrared) light allows us to work out both the size and reflectivity of the asteroid. (Contact: John Davies)