Transit of Mercury - May 9. 2016
Last time we see it on year 2006 and next will be on November 11. 2019.
Image is obtained through a William Optics refractor FLT 98/610 on Canon EOS 500D. Image below is captured in focus of Celestron EdgeHD 9,25. Mercury is small spot on the left. Real diameter of Mercury is 4 879km (for compare, Earth equatorial diameter is 12 756 km).