The Canarian Astrophysics Institute (IAC) has said that it will be researching a transit of Mercury which takes place from lunchtime today, and that it will be broadcasting live from the observatories on Teide and the Roque de los Muchachos in La Palma. The transit – where the tiny and usually invisible planet Mercury is seen to cross the face of the Sun – will take some seven and a half hours, between 12.12pm and 7.42pm (Canarian and UK time). The phenomenon needs specialist equipment to view, and as an infrequent event, means that astronomers are always excited at the prospect. They hope that the public will be enthused as well, and certainly amateur astronomers will want to join in, and the links HERE (Teide) and HERE (Roque de los Muchachos) will allow them to view live. The transit will also be broadcast on Sky-live HERE, and there is much more information on the phenomenon from the IAC HERE.