A WINTER TASK

Waikato Times, Volume 109, Issue 18247, 7 February 1931, Page 14 (Supplement)

A WINTER TASK

Sir Frank Dyson, who afler 22 years as Astronomer Royal has accepted an invitation to continue in his post for a further two years, told a London Daily .Mail reporter who visited the Royal Observatory isome interesting' things about the special problems upon which he is engaged at present. lie said: We are trying to reduce the amount of error in our calculations of the sun’s distance from the earth. The comimonly accepted figure is about 92,000,000 miles, but we know that there may be an error of one or two thousandth —about 40,000 miles. This winter has been chosen for the work because Eros, the little planet that was discovered in 1898 between us and Mars, is now only about 16,000,000 miles off. In 1900, owing to the fact that its orbit is not circular, the nearest it came to the earth was over 30,'000,000 miles—about double the distance It is now. It will not again be in a favourable position for calculations until 1961.

From October to January this winter we are therefore taking the opportunity of the nearness of Eros to recalculate the distance of the sun. This is done by comparing the angles at which Eros is observed at .widely separated observatories.

Checking up Sun’s Distance Astronomer Royal’s Activities.

We 'are also using the nearness of Eros to recalculate the mass of the moon. The margin of error there i's nearly double the margin of error in the sun’s distance. Star H®at Measured. The day’s work of an Astronomer Royal as described by Sir Frank Dyson is romantic. These 'are some of the things he told of: The is mall movement of the axis of the earth Is regularly under observation. With (fie of the largest telescopes the distances of 400 stars have been measured in the last few years as the result of 10,000 photographsAnother large telescope with a spectroscope attached has determined the temperatures of many of the brighter star's. In the day-time the sun is regularly photographed and its spots measured both In size and position. Greenwich-time is broadcast twice a day from Daventry and rea'c'hes all parts of the world. Part of the equipment of the observatory is a clock —made in England —which never alters by as much as . one-hundfedlh of a second in a day.