For more than 7 hours on this day in May, Mercury slowly crossed the face of the Sun. In this image, Mercury is the small round dot to the lower left. A sunspot group can be seen just above the center of the Sun. One thing this picture clearly shows is how tiny Mercury is compared to the Sun. Mercury even has an advantage in this image, because it is millions of miles closer to us than the Sun is.

Only about a dozen transits of Mercury are visible each century, so this is a pretty rare event. In centuries past, transits of Mercury and Venus were used by astronomers to triangulate the distances to the Sun and planets, so they were of great interest. Now that these distances are accurately known, transits have no real scientific value, but they are still interesting spectacles to watch.

Image details: Taken with a hand-held Canon Elph camera through a Personal Solar Telescope using eyepiece projection with a 26-mm eyepiece.

May 9, 2016