This May the skies above Paisley will witness a very rare astronomical event - the transit of Mercury across the face of the Sun. A transit occurs when one object appears to cross the face of another and on Monday 9th May Mercury will pass between the Sun and the Earth, appearing as a small black dot as it slowly crosses the face of our parent star.
Mercury, the smallest planet in the Solar System, orbits the Sun at a mean distance of 57 million kilometres, almost three times closer to the Sun than the Earth is, and takes only 88 Earth days to go around the Sun once. Mercury’s surface temperature reaches over 420oC when it is facing the Sun and drops to a rather chilly -173oC when facing away. One day on Mercury is equivalent to 58 Earth days and its surface undergoes the most extreme temperature change of any object in the Solar System, with almost 600oC difference between night and day. Mercury’s surface in covered in craters and resembles that of our Moon. It was most recently visited by the MESSENGER spacecraft, a NASA mission which surveyed the planet for four years between 2011 and 2015.
Transits of Mercury are rare and only happen in either May or November when Mercury's orbit is at nearest or furthest point from the Sun. May transits occur when Mercury is at its furthest point from the Sun, known as ‘Aphelion’, and the next May transit won’t be seen until the year 2049!
The transit begins just after 12 noon and unfolds over the following seven and a half hours, with the best time to view between 3pm and 5pm when Mercury crosses the middle of the face of the Sun. The best place to safely view this extraordinary event will be at Coats Observatory, which will be open on Monday 9 May from 1pm to 6pm to allow visitors the opportunity to view the transit as it unfolds. The large telescope in the observatory dome will be fitted with a safe solar filter which will block out the harmful light from the Sun – please remember NEVER to look at the Sun with unfiltered equipment as you will very quickly damage your eyesight beyond repair. Observatory staff will also be on hand to answer any questions about Mercury and the transit that visitors may have. Admission to Coats Observatory is free and there is no need to book. In the event of weather preventing the transit from being visible a ‘virtual version’ will be running in the planetarium.
For more information about the transit please contact Coats Observatory on 0141 618 6677