Brought to you by Dr. Roy Gretton, Journal Editor of The Nottingham Astronomical Society.
Please note, the NAS new permanent venue for our main meetings on the first Thursday in the month. Nottingham Emmanuel School, Gresham Park Road, West Bridgford, Nottingham, NG2 7YF.
Sky Glow โ Not a Pretty Sight!
One thing that astronomers are prone to harp on about is light pollution, the glow from artificial light that spreads up into the night sky and is gradually obliterating our view of the stars. An alarming finding, reported in the Times newspaper on January 20th this year, is that the amount of light pollution is now doubling in under 8 years (it was previously thought to be doubling every 40 years), so that each successive generation becomes less aware of the wonders that lie above their heads. Of course, some light from human activity is bound to spill into the sky, but the truth is that most of the artificial skyยญglow is totally unnecessary and is the result of carelessly designed lighting. An example of floodlighting at a local industrial site is shown in this photograph, in which the dotted lines indicate the approximate width of the lightยญbeam emitted. Presumably the intention was to illuminate an area of ground on the site, but it is easy to see that almost half the energy from this lamp is being thrown above the horizontal, and therefore up into the sky โ in other words, wasted.
This carelessness in the mounting of floodlights, repeated countless times mes, explains the hideous glow that can be seen over cities and towns, and now increasingly over the countryside, as farms, businesses and householders install more and more lamps without regard for where the stray light is going. While light pollution hardly matters for a handful of bright objects (the Moon and main planets), it is very damaging to our view of everything else in the night sky, including comets, meteors, star clusters, nebulae and galaxies. In terms of popular awareness, skyยญglow seems to be the poor relation of other types of pollution, such greenhouse gases and contaminants in rivers and oceans, and so receives comparatively little attention in the media. In the absence of the political will to do anything about it, light pollution is designed to get progressively worse. So, when you are out at night and see a lamp mounted in such a way that it sends a signi๏ฌcant proportion of its energy into the sky (and it doesn’t happen to be an airport landing light) ask yourself if it has to be this way. If enough people become aware of what is being lost, namely an area of outstanding natural beauty, the night sky, something may eventually be done to protect it.
The Planets in March & April
Throughout March and April the main planets to watch in the evening sky are Mars and Venus.
Mars, in the constellation of Gemini, continues to fade as it moves further from the Earth, while Venus will be brightening as it gets closer to us.
By early May Venus will have joined Mars in Gemini, but by then Mars be an inconspicuous orange โstar’, nothing like the brilliant object that it was in December โ although you will still be able to identify it due to the fact that, unlike real stars, it doesnโt twinkle.
As regards the gas giants, Jupiter is fast disappearing into the sunset glow as it moves into conjunction with the Sun on April 11th, while Saturn, having passed through conjunction in February, will have crept into the morning sky and will be rising an hour before the Sun in mid-ยญApril.
Meteors
April 23rd sees the peak of the annual Lyrid meteor shower. The Lyrids arenโt very prolific, typically producing about a dozen shooting stars per hour, but this year they are timed very favourably, with maximum activity coinciding with a thin crescent Moon that will soon disappear from the evening sky.
Phases of the Moon
| MAR | APR | |
| Full Moon | 7th | 6th |
| Last Quarter | 15th | 13th |
| New Moon | 21st | 20th |
| First Quarter | 29th | 27th |
