Venus is approaching the sun in advance of the June 5th Transit

On June 5th, 2012, Venus will transit the face of the sun in an event of both historical and observational importance. Amateur astronomers who manage to locate Venus in broad daylight will find that the planet has turned into a delightfully slender crescent. This is happening because Venus is turning its nightside to Earth, with only a sliver of reflected sunlight still shining over the planet’s limb.

Bellow you can watch a 24-hour movie by SOHO’s LASCO C3 coronograph that shows that Mercury is exiting stage left as Venus plunges deeper into sunlight.

When Venus is less than few degrees away from the sun, the horns of the crescent sometimes reach around and touch, producing a complete annulus. The effect is caused by particles in upper layers of Venus’s atmosphere which scatter sunlight around the circumference of the planet. The ring is very difficult to observe, and often only black-belt astrophotographers are able to record the phenomenon.