Can Light Be Considered Bad?

Astronomers would say light pollution is bad, but why?

Many years ago, I was on a fishing boat sailing from Scotland to Norway.

It was April 1997. The skipper of the boat, who, like myself, had an interest in astronomy, called me in the middle of the night. The sea was calm and the sky was clear, which was unusual for the North Sea. From the top of the bridge, we looked up at the stars, and there it was: Comet Hale-Bopp.

We had glimpsed the comet on previous nights, but this was different. The comet and the stars were so clear, and more celestial objects were visible than I had ever seen before; there was even the odd shooting star.

The reason the heavenly bodies were so clear and easy to see was the lack of light; therefore, there was no light pollution, just complete darkness.

The conditions we were witnessing must have been similar to the clear skies our ancestors had viewed long before our towns and cities were illuminated by all the artificial light, but we have come to depend upon that light.

So, what are comets and shooting stars?

Comets are icy bodies that infrequently visit us; they have highly eccentric elliptical orbits. When they venture close to the sun, they warm up and release gases that form a coma, or tail, which can be seen from the Earth.

A “shooting star” is just a fun name for a meteor; they are mostly small pieces of rock or metal that enter the Earth’s atmosphere. Some can enter the atmosphere travelling at over 250,000 kilometres per hour, and that great speed causes friction within the atmosphere, causing them to burn up, leaving a streak of light behind them.

If one is large enough and reaches land or the sea, it becomes a meteorite.

The Hoba meteorite, which was found in Namibia, South Africa, is the largest known, with a width of 2.7 metres and a weight of over 66 tons.

End

Burn or Freeze

As you know, the surface temperature of the Earth can get very hot and very cold.