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5th January 2003 meeting of the EAAS


January's lecture began with John McConnell's introduction discussing what's in the night sky for the next month. The asteriod Ceres has just reached maximum brightness of 6.8Mag and should be easily visible with a pair of binoculars or a small telescope. It is currently passing through the constellation of Gemini from Pollux towards Castor at an upward angle of 40degrees. He also gave an excellent overview of the newsletter and congratulations were made to Dr. Andy McCrea, IAA President, on his recent inclusion in the New Year's Honours List. Click here for more.

Mark McCluney's lecture was titled "How far are the stars?". This was one of the most entertaining and interesting lectures to date and was delivered in Mark's usual flamboyant style. Topics covered were wide-ranging, such as how the earth's size was accurately measured by ancient mathematician Eratosthenes. Eratosthenes worked out how to measure the diameter of the Earth using trigonometry and therefore the circumference of the Earth, but in 240B.C. the measurement of angles in degrees had not even been invented!!! Mark also described how the size and distance of the moon were calculated by Aristarchus, how we can measure the distance to close stars using trigonometry and how the distance to galaxies can be measured using Cepheid variable stars. In the early 1900's Henrietta Leavitt published two scientific papers about a peculiar type of variable star called a Cepheid variable. Although variable stars were previously recognized, the importance of this discovery was monumental. Ms. Leavitt had determined that there was a direct relationship between the magnitude of the star and its period of variability - thus the distance could be calculated. Measuring using the doppler effect was also covered and how due to the ambiguity of hubble's constant measuring these vast distances can be difficult to do accurately.

At the end of the meeting, there was a lively "Questions and Answers" section and an excellent supper, as usual, was provided by Sandy and Eileen, EAAS founders.

For more information please contact the Club Chairman, John McConnell via:

 

 

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