Dr Richard Binzel demonstrating one of the new criteria for a planet
Yesterday saw the release of the proposed new definition of a planet under which there are at least 12 planets in the solar system. This includes Pluto and its companion Charon as a double planet. Your intrepid travelling astronomer attended the press conference at which the new definition was explained to the world’s press. Under the proposal an object is a planet if it circles the Sun and it is big enough for gravity to bring it into hydrostatic equilibrium, that is being round or almost. This happens when the object is about 800 km wide or larger.
I now better appreciate the science behind the proposal but I still consider that the consequence of 12 planets in the solar system with possibly another 12 waiting in the wings is somewhat daunting. From the few astronomers here who expressed an opinion to me it seems I am in the minority. Still it will be interesting to see what happens at Tuesday’ discussion on the topic.
Dr Jill Tarter
Yesterday also saw the first of the Invited Discourses – talks by distinguished astronomers to the entire General Assembly. It was by Dr Jill Tarter of the SETI (Search for Extraterrestrial Intelligence) Institute. She talked about the difficulties of the search in “nine dimensional” space – this just means that many parameters are unknown such as the frequency and type of signal that we are looking for. However, with the new Allen Telescope Array currently being constructed, as funds permit, it will be possible to start the search in earnest.