The smallest planet in the Solar System, Mercury, will pass this Monday, May 9 between the Sun and Earth, a rare phenomenon that will be possible to observe in the part of the world where it will be daylight at that time, especially in Western Europe.
Next Monday, May 9, at 1:12 p.m. French time until 8:42 p.m. (variable depending on the location), those who are equipped with astronomical observation instruments will be able to witness a rare spectacle by following the path of Mercury, the smallest planet in our Solar System, which will appear as a tiny black disk moving in front of the Sun. Visually, » Mercury will give the impression of nibbling one of the edges of the Sun then it will cross it very slowly before emerging on the other side“explains Pascal Descamps, astronomer at the Paris Observatory. A rare phenomenon because it requires an almost perfect alignment of the Sun, Mercury and the Earth he adds.
Located 58 million kilometers from the Sun, Mercury remains relatively unexplored. The closest planet to the Sun, its diameter is only 4,780 kilometers, and it orbits the star in 88 days. If it passes quite regularly between the Earth and the Sun, every 116 days, the inclination of its orbit around the star compared to the orbit of the Earth shows us above or below the Sun. As a result, transits of Mercury in front of the Sun are rare: there are 13 or 14 per century. The last one happened ten years ago. The next ones will be in November 2019, November 2032 and May 2049.
To observe the phenomenon, the special glasses for solar eclipses will not be useful, because the planet is too small. » It takes an astronomical instrument to magnify the image of the Sun“, explains Pascal Descamps. For him, » the easiest way to see Mercury without risk will be to use a solarscope“, a sort of cardboard box fitted with a lens with a lens, coupled with a small convex mirror. It makes it possible to observe the Sun without danger by projecting its inverted image on a screen.