By mid-November, the planet Jupiter will be clearly visible in the eastern evening skies, in the constellation of Taurus the Bull. Apart from the Moon, it will be the brightest object in the night sky. Astronomers have a slightly odd way of measuring brightness. It was derived from the method used by the ancient Greeks, who labelled the brightest stars as magnitude 1, and the dimmest as magnitude 6. We have kept this fundamental scale, but we can now measure stellar brightness to a level of accuracy that the ancient Greeks could never even have dreamt of.
A star such as Deneb (the brightest star in Cygnus the Swan) has a magnitude of 1.2. This leaves a problem for stars that are significantly brighter. The solution is to start giving negative numbers to brighter stars. Sirius, the brightest star in the sky, has a magnitude of MINUS 1.1. And at the moment, Jupiter – which is even brighter – has a magnitude of minus 2.8. The Moon has a magnitude of minus 12.7, and the Sun has a magnitude of minus 26.7. (Those of you with a mathematical bent should note that the scale is logarithmic. A decrease of magnitude of one represents an increase in brightness by a factor of 2.512. This means that the Sun is about 400,000 times as bright as the Moon.)
The Torbay Astronomical Society will be continuing with its usual series of meetings. We usually meet on two Thursdays every month, at Torquay Boys’ Grammar School in Shiphay Manor Drive, starting at 7.30pm.
On November 8, Dr Ed Gomez from Cardiff University will be talking to us on the topic The Las Cumbres Observatory Global Telescope Network, in the school’s Business & Enterprise suite. At the November 22 meeting (provided we have a clear sky), we shall be observing both the Moon and Jupiter, making use of our new telescope.
Visitors and new members are always welcome. There is a £3 charge for visitors to the lecture evenings, and a £2 charge for the observational evenings. Annual membership is a mere £15, with a reduction to £10 for senior citizens.