Comet ISON is coming!

As Comet ISON draws near to its close approach with the Sun in November, much uncertainty remains over how brilliant it will be. Dominic Ford speaks to Matthew Bishop at the Lowell Observatory to find out more. He also talks to Apostolos Christou from the Armagh Observatory about a group of asteroids which closely follow the orbit and Mars, and appear to fragments of a much larger pair of asteroids which collided. Tamela Maciel from the Cavendish Laboratory in Cambridge reports on the lonely exoplanet which doesn't seem to have a parent star, and Kirsten Gottschalk from the International Centre for Radio Astronomy Research reports that the non-detection of gravitational waves by radio astronomers is starting to rule out some theories of how black holes grow.