Friday, April 25, 2008

The Zodiacal Light and Lasers in the Sky

A few times recently we have noticed a glow in the western sky after sunset. We had thought that it might be some light pollution coming from the main center of the village. This would not be a major problem as La Palma has very strict laws governing light pollution. So this evening we decided to go out for a drive having spotted this glow and find out where it was coming from, and to our surprise we found that the glow did not have a terrestrial source. Having read a bit I discovered that what we were seeing was what is known as the Zodiacal Light. This is the light from the sun being reflected off very small grains of dust in orbit around the Sun. It is only visible in dark non light polluted skies. Unfortunately I didn't manage to get a picture of this but I will keep an eye out and try and get one.

When we got back from our little drive around to try and find the source of the glow, as we got out of the car I looked up to the sky as I normally do and noticed something in the sky. What I saw was a straight line across the sky. This is the 25W Laser which is projected from the William Herschel Telescope to provide an artificial guide star for the adaptive optics system which allows the removal of the effects of the air turbulence which is what causes the stars to twinkle.


30sec Exposure showing Laser


2 1/2 minute Exposure showing Laser tracking stars

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