Violent Universe – 22nd May 2014

Chris Lintott was unable to visit us as he was on La Palma, so Tony Sizer stepped into the gap at short notice, and gave us an informative and entertaining talk entitled Violent Universe.

The Universe is not as benign to life as many people think. From the moment we are born it is attempting to kill us. There are several examples of what might be called “Weapons of Mass Destruction” which the Universe might employ against us.

“Things That Go Bump”, i.e. things which might collide with the Earth, include meteorites and asteroid. Collisions with such objects are about the only disasters which we might have a chance of avoiding. Spaceguard is an organisation which is searching for Near Earth Objects and none so far has been predicted to be on a collision course with the Earth, although Apophis gave us a nasty scare a few years ago.

A close approach of a star could be problematic, not because of the radiation from the star, but as a result of the gravitational effect of the interloper on the orbits of the planets or, in the case of a more distant approach, on the orbits of the comets in the Oort Cloud. The orange dwarf star Gliese 710 might cause problems of this nature in about 1.5 million years time.

“Things That Go Bang” include Novae, Supernovae and Gamma Ray Bursters. These might cause damage to the Earth’s ozone layer which would then be unable to filter out the Sun’s ultraviolet light. Fortunately there appear to be no precursors of these objects within a dangerous distance of the Earth at the moment, but who knows what might happen in the future?

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