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Rare Mercury transit visible with Leiden telescope

On Monday 9 May Mercury will pass between the Earth and the Sun. This rare event can be followed in the Leiden Observatory. The Observatory's new solar telescope produces a very clear image and offers a unique opportunity to observe Mercury at the highest magnification possible in the Netherlands.

Mercury is the most central planet in our solar system. On 9 May it will pass between us and the Sun, making the silhouette of the planet visible against the Sun. This doesn't happen often: the last time that Mercury passed in front of the Sun was ten years ago. The next Mercury transit that will be visible in the Netherlands will be in 2039.  


Few people have ever seen the planet because it is generally too close to the Sun, which makes the transit on 9 May a unique opportunity to see the silhouette of the planet. But observers should take care: observing the Sun without special protective glasses can damage the eyesight!  The transit can be viewed safely using the special solar telescope in the Leiden Observatory. The telescope was financed in part by the 'Bring the sun to Leiden' crowdfunding project. It projects an image of the Sun - almost a metre in diameter - on the wall of the Observatory.   

Planets around other stars

When Mercury passes in front of the Sun, it has the effect of making the Sun temporarily slightly less bright than normal. Professor Ignas Snellen will explain in a lecture how planets orbiting around other stars are detected using this technique: when the planet passes in front of a star, the star emits less light than normal.  


You can observe the Sun throughout the whole afternoon, enjoy the lecture on planets around other stars or take part in an interesting educational programme organised by Universe Awareness  specially for children.

Date: Monday 9 May 2016


13:00 - 20:30 hrs. - Continuous programme
17:00 – 17:30 hrs. - Lecture by Professor Ignas Snellen: Planet transits within and outside our solar system
Location:  Old Observatory, Kaiserstraat 63  Leiden. 

Please note:  because of construction work, the Observatory is only accessible via the Zegersteeg and a small set of stairs. If you have mmobility problems, please send an email to Mercurius2016@strw.leidenuniv.nl, and we will try to find a solution.

More information:
Mercurius details: (Marc van der Sluys / hemel.waarnemen.com)
How you can look at the Sun safely 
Universe Awareness: Inspiring every child with our fantastic Universe


About Mercury

Mercury is very small and this event can therefore only be seen using a telescope. The transit was observed for the first time in 1631, in spite of the fact that Greek astronomer Ptolemy had predicted 1500 years previously that the outline of Mercury could be seen. 

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