A Transit of Mercury occurs on Monday 9 May 2016 which is visible in its entirety from the British Isles. A transit such as this occurs when a planetary body, Mercury in this case, comes between the Earth and the Sun. A small black dot can be seen moving across the face of the sun.
Mercury will look like an extremely small sunspot, crossing the disk of the Sun in 7 hours 30 minutes. This event is probably best seen by watching a webcast of the transit. Do not observe the Sun without suitable eye protection.