Astronomers are watching with delight as Mercury passes between Earth and the Sun this afternoon.
The rare transit of Mercury began at about 12.35pm UK time and is set to continue until just after 6pm.
The silhouetted planet will appear to touch the Sun in a dazzling image which will look as though it is passing over the solar surface.
It is an irregular sight to behold and the next opportunity to do so will be in 2032.
Prof Mike Cruise, president of the Royal Astronomical Society, said: "This is a rare event, and we’ll have to wait 13 years until it happens again."
There are around 13 or 14 such transits every century.
People are warned not to look at the event with the naked eye and are advised to consult guidance from the Society for Popular Astronomy should they wish to observe it.
It is advised to use a telescope and a variety of filter material in order to protect the eye.
