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Seeing stars

A few days later, our journey took us through Lake Tekapo, which is roughly in the centre of New Zealand’s south island and around 700 meters above sea level. The mountains surrounding Lake Tekapo protect it from coastal weather systems so the township enjoys some of New Zealand’s highest sunshine hours - the perfect place to build an observatory.

The observatory is situated a further 300 meters above sea level on the top of Mount John. There are four principal telescopes at the observatory, of which the largest is a 1.8 meter telescope dedicated to the “microlensing observations on dark matter” (MOA) project.

Here, the team uses a gravitational microlensing technique to make observations of extra-solar planets, among other things. The microlensing technique enables a distant star to be magnified by the gravitational field of a nearer collinear star, which effectively acts a lens. There is a lot more information on this on the MOA homepage.

I have never been to a large-scale observatory before so it was great to have the opportunity to see inside a dome. A 1.8 meter diameter mirror is bigger than you imagine it would be and certainly puts the challenge of developing mirrors for projects such as the ESO’s very large telescope (VLT) into perspective.

The VLT will consist of four 8-meter telescopes which can work independently or in combined mode. In the combined mode, the VLT will provide the total light collecting power of a 16-meter single telescope, making it the largest optical telescope in the world.

An added bonus of our trip to Lake Tekapo was the night-time star-gazing tour that the observatory runs. This gave us the opportunity to see just why Mount John is an excellent place to build an observatory.

The sky was clear and the number of stars was incredible - so many more than you can see from a light-polluted city. Our guides pointed out a number of constellations - including the Southern Cross, which I had never seen before, and Orion, which is upside down to what we are used to in the Northern hemisphere. We also got the opportunity to view Alpha-Centauri (the closest star to our solar system) and did you know that this is actually a system of three stars?

So if you are ever in New Zealand, the Mount John Observatory is worth a stop!

Posted by Jacqueline Hewett on April 24, 2008 1:26 PM | Permalink