A public lecture by Dr Jane Greaves
The Sun is surrounded by a belt of comets, lying just outside the orbits of the planets. Some of these comets fall in towards the Sun and their paths can intersect with that of the Earth. During the early history of the Earth, there were many violent impacts on our planet, some so extreme they could melt the landmasses or remove the atmosphere. A re-arrangement of the planets dispersed most of the Sun's comets billions of years ago, so we are now relatively safe from such a catastrophic impact. However, many nearby stars that are otherwise similar to the Sun show evidence of vast swarms of long-lived comets. The evidence for this will be discussed, as will the implications for prolonged bombardment of Earth-like planets that may exist around the stars, and whether the rise of extra-terrestrial life would be halted by this, or perhaps helped in some exotic form.
Dr Greaves is a Reader at the University of St Andrews, appointed by the Astrobiology Initiative of the Scottish Universities Physics Alliance.