Transit of Venus 2012

On June 5/6th, 2012, between 10.09 pm and 4.49 am UT a black spot will slowly cross the sun's disc. This transit will be observable from all places on the daylight side of the earth.


10.09pm UT	4.49m UT

The above pictures show the countries from where the begin (left) and the end (right) can be observed, respectively. (For more information about the visibility click here.)

This extremely rare phenomenon will be caused by Venus overtaking the Earth exactly between Sun and Earth. Therefore, it is called a transit of Venus .

The transit can be observed by ...


using only a pair of solar filters	projecting the sun with field glasses	looking and photographing through a telscope
These pictures have been taken during the 2004 transit.

The passage will look slightly different when be observed from different sites on earth:

Venus will have slightly different positions on the Sun's disc when being observed simultaneously from different sites on Earth.
The ingress of Venus into the sun's disc will be observed at slightly different times when being observed from different sites. Similarly will the egress be measured at different times.

These so called parallax effects are due to the fact that Venus is not as far from Earth as the Sun. Therefore, measurements of the effect allow the derivation of the distances of Venus and the Sun.

This website proposes two international projects of observing, photographing and measuring the transit:

Simultaneously photographing Venus in front of the Sun
Combinating photos from sites all over the world will make the different distances of Venus and the Sun visible and allow to determine these distances.

Measuring and Evaluating the Contact Times of Venus
Observing of Venus' ingress and egress and comparing contact times precisely measured at distant sites on Earth will allow to derive the distance to the Sun.

In order to participate in these projects nothing else will be needed than an exact going clock and a small telescope or binocular, a solar filter (glas or thin metal sheets), a stable tripod and, for project 1, a digital camera of sufficient large equivalent focal length (about 400 mm).

The main goals of these projects are

to initiate international cooperation between schools, amateur astronomers and universities in order to combine their transit observations,
to repeat the historical determination of the distance from Earth to the Sun (the so-called Astronomical Unit AU) with modern methods,
to get an own impression of the size of our solar system and
to derive an own measure of the Astronomical Unit.

The projects proposed here will be very similar to those we have organized for the transit in 2004.

		Editors:	Udo Backhaus	last update: 04.04.2012
			Stephan Breil

Internet Project

Observing, Photographing and Evaluating the

Transit of Venus, June 5/6th, 2012