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The South West Herts Astronomical Society
SEEING STARS

How many stars can you see in the night sky above Rickmansworth? From a typical suburban location such as ours you will be lucky to spot more than one or two hundred, and considerably fewer if the Moon is full. Move to a reasonably dark site a few miles from the town centre however and the number of stars visible will rise to a thousand or more, and if you travel to the darkest viewing sites, far from the bright lights and atmospheric pollution of cities and towns, the number shoots up to somewhere between five and six thousand.

Surprisingly it is often easier to find your way around the sky when fewer stars are visible. Most people have little trouble spotting such familiar constellations as the Plough, visible all year round in the northern sky, or Orion, the hunter with his sword and belt, visible in the southern sky in winter months. Move to a dark Welsh valley however, where the seeing conditions are excellent, and you may well find that even the familiar constellations are hard to pick out among the glittering array of stars studding the night sky.

The stars are unimaginably distant from us. Even the closest is more than a quarter of a million times further from us than our own Sun, and the brightest star in the heavens, Sirius (the dog-star, visible to the southeast of Orion), is twice that distance.

Of course there are some bright objects in the sky which are very much closer, but they are not stars. Our closest neighbour in space, the Moon, orbits the Earth at a distance of about a quarter of a million miles (roughly ten times the circumference of the Earth). The planets circle the Sun in the same way as we do, but at different distances and speeds, so that their distances from us vary over the months and years.

Venus, Jupiter and Saturn regularly outshine the stars, as does Mars at its best appearances, such as in 2003 when its closest approach to Earth for 60,000 years made it a spectacular sight in the summer skies. Even Mercury, the planet closest to the Sun, shines brightly in the sky, although its light is usually well masked by the bright glare of the early morning or late evening Sun.

Telescopes reveal many of the most beautiful wonders of the sky, which are often too faint to observe with the naked eye or binoculars. Nebulae, remote galaxies and dense clusters of stars can be resolved through larger instruments, and time-exposure photographs can reveal spectacular colours and detail not visible to the eye.

Rickmansworth is the home of the South West Herts Astronomical Society, which attracts interested amateurs from Chorleywood, Watford and the surrounding area. Regular monthly meetings are held, where guest speakers often give fascinating talks on various aspects of astronomy. The society is also fortunate to have its own observatory at a good dark sky site at Flaundon, just a few miles from Chorleywood. The observatory is equipped with a large reflecting telescope constructed by enthusiasts in the society, and regular observing sessions are held throughout the year.

If you are interested in finding out more about the wonders of the night sky above Rickmansworth why not consider joining us? Visitors are more than welcome! For more information look out for our new website, swhas.org.uk, or telephone me at 01923 776159.
Graham Marett (Chairman SWHAS)

The views expressed on this website are those of the individual contributors, and do not necessarily reflect those of the R&DRA Committee as a whole.

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