A planet to discover

Published on March 6th, 2013 | by Jo

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# Mathematics & the Moon

This shot was taken from the balcony of our house in the suburbs of Melbourne on the evening of Saturday 23 February 2013.

The interconnection between maths and astronomy has always fascinated me. Historically, the Babylonians knew much about the stars, and developed mathematics to help them understand it. They knew where each star would be in the sky throughout the year and had sophisticated systems for calculating positions. Theirs was a Base-60 number system. We owe the use of 60 in our telling of time and in the number of degrees in a circle to the Babylonians.

Our eldest son and his dad built the telescope ten years ago, grinding the mirror by hand. A great deal of mathematics went into getting the mirror just right.

Grinding the mirror was especially time-consuming and father and son learnt the physics and mathematics they needed to do it as they went along. They were supported by the Instrument Making group of the Astronomical Society of Victoria, a great bunch of people who are always very keen to encourage the building of new telescopes.

Mathematics was used to decide which focal length we wanted. Focal length helps determine the magnification:

magnification = focal length of telescope / focal length of eyepiece

Also, mathematics (well really physics) was used to understand the reflection patterns we got from the mirror when we tested it during the grinding process. This helped us correct the imperfections in the mirror.

As a family, we have travelled throughout New South Wales and Victoria with the telescope. Regional Australian skies are spectacular, but we are always amazed when we have a great viewing night right in our own backyard – even with all the light pollution. On the same night that this shot was taken, we saw Jupiter, its rings and three of its moons. My favourite constellation is the Pleaides (also known as Messier45). You might know it as the logo for Subaru.

Now at 21, Lachlan is about to complete a Bachelor of Science degree at The University of Melbourne, majoring in maths and physics. I often wonder if the spark lit by an interest in the stars at age 11 had anything to do with the path he has chosen.

Janine McIntosh
Schools Manager, AMSI

Photo credit: Lachlan McIntosh, taken with an iPad camera help up to the eyepiece of a 8 inch Dobsonian telescope[subscribe2]