Transit of Mercury

Mercury's transit of the Sun, on 9 May 2016

Image copyright: Martin Heigan

On 9 May 2016, Mercury passed in front of the Sun, where it was visible from Earth as a tiny black disc, moving across the Solar surface over the course of a few hours.  Mercury orbits around the Sun every 88 days, but because it orbits in a plane 7 degrees tilted from Earth’s orbit, it normally appears to skip either above or below the Sun. Transits like this one, where it lines up with the Sun from our point of view, are quite rare: Last time it happened was in 2006, and it won’t happen again until 2019.

This is a composited time-lapse sequence of Mercury’s transit path, photographed between 13:05 – 17:25 from Johannesburg.  It was a challenge to image in partly cloudy conditions. At S 26° Latitude, the last bit of the transit was not visible due to the Autumn Sun setting before the transit was complete.

Canon 60Da DSLR.
GSO 6" f/4 Imaging Newtonian Reflector Telescope.
6" Thousand Oaks Optical R-G Solar "White Light" Solar Filter.
2" 2x Tele Vue PowerMate.
Tele Vue Sol-Searcher.
Celestron AVX.

Photos stacked in RegiStax.
Time-lapse composited in Photoshop.