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Star Count 2021

By February 11, 2021February 13th, 2021Blog

Star Count 2021

In an effort to better understand the loss of the night sky due to light pollution, astronomers are calling on star-lovers and romantics to enjoy a night under the stars and give them a helping hand, you can become a scientist for the night. This is a great activity for the whole family that you can do from home, whether you live under dark skies or in a town with lots of light pollution.

This year, the campaign runs from 6th February to 14th February.

Participants are asked to count the number of stars they can see in a quadrangle formed by the brightest stars in the constellation of Orion. It is very easy to find in the night sky, with the four brightest stars being the intensely red/orange coloured Betelgeuse (some of you might know this star as Beetle-Juice), Bellatrix (a name Harry Potter fans will recognise), Rigel (the brightest star in Orion that scientists think may be up to 300,000 times brighter than our sun!) and Saiph (about 60,000 times brighter than our sun).

Of the four stars, Betelgeuse, Rigel and Saiph are so large that they will end their lives in a gigantic explosion, called a supernova. These explosions throw elements out into space from which new solar systems, like ours, are formed. Bellatrix will have a more sedate end, becoming a beautiful planetary nebula, as will our own sun, with a white dwarf star in the centre.

If you would like to participate here are the details for the project:

In addition, you can also email your results to and we can produce a local light pollution map.

Why is looking at light pollution important?
Most people are familiar with air, water and land pollution but are not always conscious of light being a contaminant. At night time many of us have become very familiar and comfortable with artificial lighting. At the Astronomical Observatory in St Peters one of the most frequent comments we hear from visitors is “I have never seen the Milky Way before” It takes people by surprise, the night sky to so many visitors is just a diffuse orange glow. Telling them they are looking into the very core of our galaxy, some 100,000 light years away leaves quite an impression.

Light pollution has many hidden effects, it interferes with normal circadian rhythms, impacting human health and immune function. It adversely impacts behaviour in insects and animals. Unnecessary light pollution also wastes energy which is expensive and it contributes to climate change.

Other objects to look at:
Also look to the right and up a little and you will see the red planet Mars. If you look to the left and down a little you will see the brightest star in the night sky, Sirius. If you watch it for a few minutes it will appear to flash in many different colours from blue-white-yellow-red. The atmosphere splits the starlight into these different colours, much like a rainbow. Also, look at the central lower half of the Orion constellation, you might see a “fuzzy patch”. This is the Orion Nebula, a mixture of space dust and gas where new stars and solar systems are being formed, if you have a pair of binoculars you will clearly see the nebula and its bright centre, illuminated by a group of stars called the Trapezium Cluster.