Venus has done it again,
Mercury in 2016, too, and Mercury will do it again on November 11^th, 2019

Sunrise in Hannover, Germany, shortly before cloudes cover the Sun

... and her parallaxe became visible and measurable!


Superposition of simultaneously taken pictures taken in Hannover, Germany, and Canberra, Australia	The corresponding daylight side of the Earth, the "view" from the Sun to the Earth

The outcomes can be viewed on the result pages of the photography project and the contacttimes project.

Description of the project

On June 5/6th, 2012, between 10.09 pm and 4.49 am UT a black spot slowly crossed the sun's disc. This transit was 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) could be observed, respectively. (For more information about the visibility click here.)

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

The transit could 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 looked slightly different when be observed from different sites on earth:

Venus had 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 was observed at slightly different times when being observed from different sites. Similarly the egress was 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 describes 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 was 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 have been

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 described here have been very similar to those organized for the transit in 2004.

		Editors:	Udo Backhaus	last update: 14.11.2017
			Stephan Breil

Internet Project

Observing, Photographing and Evaluating the

Transit of Venus, June 5/6th, 2012

Venus has done it again,
Mercury in 2016, too, and Mercury will do it again on November 11^th, 2019

... and her parallaxe became visible and measurable!

Description of the project

Internet Project

Observing, Photographing and Evaluating the

Transit of Venus, June 5/6th, 2012

Venus has done it again, Mercury in 2016, too, and Mercury will do it again on November 11th, 2019

... and her parallaxe became visible and measurable!

Description of the project

Venus has done it again,
Mercury in 2016, too, and Mercury will do it again on November 11^th, 2019