Thursday, 1 November 2007
Prof Alan Fitzsimmons of QUB gave an up-to-the-minute report on Comet 17/P Holmes tonight at the start of the IAA lecture by Dr Andy McCrea. The comet remains bright, with the coma expanding in a perfectly circular disc (from our perspective). But as the total brightness is no longer increasing, even with the increase in size, that means that the disc must be optically thin, i.e. it's mainly thinly scattered dust. The brightness is expected to decrease gradually over the next few weeks. There's no sign of a tail, and none would be expected, as if there is one, it will be pointing directly away from Earth. BUT - there is a chance that there might be another outburst! This happened some weeks after the outburst in 1892, during which the comet was discovered. This was not quite as bright as the original outburst, but it's still worth looking out for. And no, they still don't know what caused either this, or the original, outburst!