The transit of Mercury passing across the Sun on the 11th November 2019. The image was taken from Arlington, Virginal, USA. Mercury is seen as a very small black dot close to the right hand edge of the Sun. Transits of Mercury, as seen from Earth, occur 13 or 14 times per hundred years. This is more frequent than transits of Venus, mainly because Mercury is closer to the Sun and orbits it more rapidly. All transits of Mercury occur in May or November, the next taking place on the 13th November 2032. Transits of Venus and Mercury are used to refine the transit method technique which is used to discover exoplanets orbiting stars outside the Solar System.