Important announcement: Due to unforeseen circumstances it is no longer possible for Professor Robin Catchpole to travel to Cape Town to present his course, Threats to the Earth from asteroids and comets: should we worry? Professor Phil Charles will present this course in his place (click here to see his curriculum vitae). Should you wish to cancel your registration for this course please contact the Summer School office.

Dr Robin Catchpole, Institute of Astronomy, Cambridge, United Kingdom

On 15 February 2013 an object exploded twenty three kilometres above Chelyabinsk, releasing twenty times as much energy as the atomic bomb that devastated Hiroshima. The shock wave arrived three minutes later, giving people enough time to rush to their windows and as a result 1 500 people were injured, mostly by flying glass. The explosion over Tunguska in 1908, was ten times more powerful. Neither of these impacts left a significant crater. One hundred and eighty impact craters have been identified on the surface of the Earth. The most recent dates from about fifty thousand years ago, while the largest and oldest is the two thousand million year old Vredefort ring in South Africa.

This three-lecture course will explore the potential threats to Earth from asteroids and comets. Asteroids that have orbits crossing the
Earth’s orbit are referred to as NEA (Near Earth Asteroids). All evidence suggests that the risk of being killed by a NEA is comparable to many other risks that we take seriously. As a result, in 2005 the US government directed NASA to detect, track and catalogue all objects larger than 140 metres, with orbits laying close to the Earth’s orbit. Comets are a rare but potentially more serious threat to the Earth, as they can appear in the inner solar system with little warning, move fast and follow less easily predictable orbits. This course will provide an overview of the history of impacts with the Earth, some possibly within human memory, and suggest what we can do to prevent them.

1.    Where is the evidence?
2.    Know your enemy
3.    What are we doing?


Course code: 1034

Date & time: Monday 27–Wednesday 29 January 11.15 am


Full: R225,00

Staff: R112,00

Reduced: R57,00