In this month - December

6th December 1882

The Transit of Venus, the second and last transit of Venus of the 19th century, the first having taken place eight years earlier in 1874. Sydney Observatory ployed an important part and the NSW Government astronomer, H.C. Russell co-ordinated observations from different sites in NSW including Woodford Academy in the Blue Mountains. Because of its fortuitous location and even though the transit began before local sunrise, New Zealand was able to play an important role in the quest to determine one of astronomy’s fundamental yardsticks, the mean distance from the Earth to the Sun now known as the ‘Astronomical Unit’, or AU.

13th December 1920 Albert Michelson and Francis G. Pease made the first measurement of the diameter of a star other than the Sun by means of the beam interferometer invented by Michelson. They measured the red giant Betelgeuse which was selected because of its great size. The experiment was a success and the apparent angular size of Betelgeuse was found to average about .044 arcseconds.

30th December 1985

Puck, a moon of Uranus, is discovered by the Voyager 2 spacecraft and given the designation S/1985 U 1. The orbit of Puck lies between the rings of Uranus and another moon, Miranda. Little is known about the moon, it’s surface is heavily cratered and is grey in colour. The name Puck follows the convention of naming Uranus's moons after characters from Shakespeare.

BORN

25th December 1642

Sir Isaac Newton. English astronomer, mathematician and physicist who is widely recognised as one of the most influential scientists of all time. Apart from his work on universal gravitation he developed the three laws of motion which form the basic principles of modern physics. His discovery of calculus led the way to more powerful methods of solving mathematical problems. He was a true genius in astronomy.

7th December 1905 Gerard Kuiper. Dutch-American astronomer. Discovered Uranus's moon Miranda, Neptune's moon Nereid, carbon dioxide in the atmosphere of Mars and the existence of methane in the atmosphere of Saturn's moon Titan. He speculated about the existence of a region of space extending from Neptune to approximately 50 AU from the Sun where it is believed many comets originate from. It was named The Kuiper Belt after him.

22nd December 1911

Grote Reber, American astronomer (pictured above , credit : NRAO/AUI/NSF). He was a pioneer of radio astronomy and was instrumental in investigating and extending Karl Jansky's pioneering work in this area. He conducted the first sky survey in radio frequencies. In 1954 he moved to Australia where he lived the remainder of his life living in Tasmania and working at the University of Tasmania, where there is a museum about his work and radio astronomy.