Transit of Venus

On the 6th June 2012, Venus is going to pass in front of the Sun. Venus will start to move across the Sun (ingress) at 8:15am and will finish it’s transit (egress) at 2:45pm in Melbourne. This makes Australia one of the optimal places to observe this astronomical event.

Transit of Venus

Image from Wikipedia

The Transit of Venus last occurred in 2004 and the next one will be in 2117, so it is a once (or twice) in a life-time event. Despite Venus passing between the Earth and the Sun every 1.6 years, the transits occur in pairs of 8 years, which are then separated by over 100 years. This arises due to the orientation of Venus’ orbit, so Venus usually passes above or below the Sun from the Earth’s perspective.

The history of the Transit is quite remarkable for Australia too. Halley (of the comet fame) predicted the next one for 1761 and would provide a method to measure the size of the Solar System, but would not be alive to see it. Bad weather meant it wasn’t until 1769 that the transit would be viewed. The Endeavour, with Captain James Cook, set out to observe the transit in Tahiti on 3rd June 1769. The remainder of his voyage went on to find Australia and New Zealand.


So, how do we get to view this momentous event?

There are many options and they all require you not to look straight at the Sun, especially through a telescope, binoculars or camera.

  • Obtain a solar telescope, specifically for observing the sun
  • Fit your current telescope with a solar filter that blocks out 99.999% of the Sun’s rays. For a large telescope (over 8″) an off-centre filter is more than suitable.
  • Make your own filter using solar film. Ensure you continually check that there are no holes or scratches on your filter whenever you use it
  • If you have a small refractor telescope, you can make a projection screen.
  • You can set up a pair of binoculars to project an image.
  • You can purchase inexpensive disposable solar glasses for viewing the sun.

If this is not possible, there are many websites doing live feeds, so you can observe the event from the comfort of your lounge/classroom.

Want to make your own measurements?

There are a lot of people taking measurements and many ways you can get involved and make the calculations.

Here are just a couple:

You can practice with images taken from the 2004 transit.

You can use a Parallax calculator.

How is The University of Melbourne and TiS getting involved?

  • The Astrophysics Group at the University will have a telescope set up with a projected image for the duration of the transit at the athletics field until 10am, then onto the Concrete Lawn.
  • The Melbourne Planetarium will be hosting a breakfast, talk and viewing opportunity with one of our telescopes, in addition to their own.
  • Quantum Victoria will have their TiS telescope running for the day with a couple of schools observing the event.
  • One of our host schools, Pascoe Vale Girls College, going to spend the day taking images of the transit to provide the data for measuring the Astronomical Unit (AU distance between the Sun and Earth) just as Captain James Cook did in 1769.

More resources

Transit of Venus Australia official website

Information on Wikipedia

Transit of with History, activities, free iPhone App and safety information


Safety is a huge aspect of this event and much caution should be taken whenever you are observing the Sun.

  • NEVER look directly into the Sun
  • Sunglasses and smoked glass are not enough, you must only use film or glass that has been specifically made for solar observation
  • Always use a filter on the telescope (solar glasses are not enough)
  • DONT look through the finderscope to align your scope, use the shadow of the telescope.
  • Each time you use your filter check for holes or scratches, DO NOT use if there are any scratches and fit holes if possible.
  • Read all the instructions on any device you are using.

One comment on “Transit of Venus

  1. Pingback: 2013 in review | Telescopes in Schools

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