A couple of UK based astronomers just suggested a rather chilling idea that seems to have found favour with the astronomical community. Bill Napier at Cardiff University and David Asher at the Armagh Observatory have claimed that there could be thousands of dark, dormant comets which we cannot see.
With scientific estimates placing the likely number of comets in our solar system at around the 3000 mark, and with only 25 accounted for, the theory seems to be a very real possibility. Various space agencies are engaged in a project to try and monitor potentially threatening comets and asteroids. The group effort is known collectively as Spaceguard and many of the leading figures have agreed there may well be a number of dark comets.
Dark comets reflect less light than the bright kind because they have no surface water and absorb sunlight. In fact another scientist, Clark Chapman, from a Research Institute in Colorado has suggested that they could possibly be detected because of the heat they emit. The fact we can’t currently detect these comets means that one could plough into the earth before we have had a chance to do anything about it.
It is still unclear exactly what we would do if we knew a comet or asteroid was going to hit earth. The asteroid ominously named Apophis was thought to be a threat as it will pass close by to earth in 2029. There were various discussions about whether a mission should be sent to investigate with the idea that they could initiate some kind of deflection but the threat was recalculated as extremely low and the panic passed.
If threats we know about can cause such a level of distress and worry it is pretty terrifying to consider we could be blindsided. The closest shave we’ve had was in 1983 but that comet was still over 5 million kilometres away.