Adrian Dening's Stars Over Somerset

Wednesday, 21 June 2023 17:00

Monday 26th June to Sunday 2nd July 2023

If you look towards the west just after dark, it is still possible to see Venus close to the horizon, shining brightly at a magnitude of around -4.3 with Mars a little above and to the left of it. Mars will appear as a red dot and will not be as bright, with a magnitude of +1.7

A little further left again will be one of the brightest stars in the night sky - Regulus - which is the alpha star in the constellation of Leo the Lion. It will have a similar magnitude to Mars, but without the reddish appearance.

I have mentioned binary stars before, where a pair of stars are kept relatively close together by their mutual gravity and the two stars orbit around each other. Some binary star systems are known as "visual binaries" and the individual stars can be resolved in a telescope. Others cannot be separated visually and astronomers instead resort to measuring minute shifts in the stars' positions or their brightness to calculate the presence of a binary.

Well Regulus is actually a quadruple star system, but it is not possible to isolate the individual stars with your telescope, so what you are really observing is the main star, Regulus A which is approximately 79 light years away.

The constellation of Leo also contains an asterism (or easily-recognisable shape) known as the "Sickle". It comprises the stars that make up the lion's head and shoulders, resembling a backwards question mark.

Screenshots courtesy of Stellarium
Sickle asterism image courtesy of Pete Lawrence
Copyright Adrian Dening and Radio Ninesprings 2023
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