Venus has done it again ...


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: 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:

  1. 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.
  2. 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

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


Editors: Udo Backhaus
 last update: 16.09.2012
Stephan Breil