The Universe in the Classroom

The Story of the Transit of Venus

Venus Transit 2004

On June 8th this year, the world will get another rare glimpse at a transit of Venus. The transit will begin at about 5:13am UT when the leading edge of Venus just touches the sun. This is called 1st contact and can be seen from most of Africa, Europe, Asia, and Australia. In North and South America, the transit will already be in progress at sunrise. In Australia, the sun will be setting with Venus in transit and the western portions of the US and Canada will not be able to see the transit at all (ie the sun will rise after the transit has completed). The transit will end about six hours later at 11:26 UT. Taking into account anticipated weather conditions and viewing geometries, the best places to view the transit will be Africa and the Middle East. The planet Venus will subtend just shy of one minute of arc which is 1/30 the diameter of the sun so it is likely that the transit can be viewed with only a solar filter and not require the use of optics. Of course, you will get a much better glimpse of the event using a telescope with solar filter. It should be noted that no one has ever viewed a Venus transit through an H alpha solar filter so this would be desirable if you or your club have one.

The Astronomical League is teaming with NASA to support a number of events relative to the transit. First, AL has established a Transit of Venus Observing Certificate Program that is accessible from their web site. It involves calculations of the distance to Venus and the AU as well as the Venus diameter and velocity at the time of the transit. In addition, careful observers should be able to detect the black drop effect. Other certificate requirements involve holding public events and assisting schools in understanding and viewing the transit.

NASA through their Office of Space Science has embarked on a large, international education outreach program around the transit. For this, NASA is seeking the help and participation of amateur astronomers to support public outreach activities. To sign up, just go to and click on "Amateur Astronomers". You will receive a packet of materials you can use as well as a wealth of web based resources describing the transit, methods of observing, and many activities and resources you can use for your Venus Transit event.

Paper Plate Venus Transit Activity

With thanks to Chuck Bueter, author of "Paper Plate Astronomy" (, you can simulate the movements of the Earth and Venus using only a paper plate and markers. Through this activity, students will show the relationship between the orbital period's of the Earth and Venus, be able to explain why Venus transits occur at predictable intervals, and understand how Venus' orbital inclination plays a critical role in the timing of transits.


NASA Venus Transit Web Site:

Paper Plate Astronomy:

NASA Search for Extrasolar Planets:

Eclipse Viewing and Geometry:

Hipparcos Website:

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