Even after being a keen astronomer for many years, I still find some very simple concepts and facts surprising. For example, you would think that on a clear night you would be able to see many things far out into space. In some respects, this is correct as you can see thousands of stars. But our galaxy, the Milky Way, has approximately two hundred billion stars. You are only seeing a very small percentage of it (0.000003%) which are objects either relatively close or large. It is possible to see between and beyond these objects to other galaxies, but it is hard with just your naked eye.
Looking for planets in the sky.
In the main, planets all follow the same arc across the sky called the ecliptic. So if you know where the arc is in the sky and follow it, the planets are not very far away. This is because planets were created from a thin disc of debris circling the sun. The position and angle of this disc set in place the planets’ orbital plane when they were formed. The sun and moon also appear to follow this path through the sky. I will come back to how to spot planets later on in the year when we are able to spot one or two.
Orion
Last month I showed you how to find Polaris (The North Star). This month we will be looking across the sky towards the south-west to find another familiar constellation, Orion.
Orion dominates the winter night sky. It will be familiar to many and is shaped like a very large figure eight (or hourglass). Orion is named after the hunter in Greek mythology. In more light-polluted areas of Britain, many people will only be able to see the figure eight part of Orion. However, in and around Embsay we are lucky enough to see all of the constellation due to our crisp clear skies, particularly around the time of a New Moon (15th February) as he holds a shield in front of him with one arm and a weapon with his other arm above his body.
If you look closely at the top left star of his Orion’s body you will observe a star called Betelgeuse. This star looks very different to others in the sky. It seems to be a reddish/orange colour and very bright. It is a red ‘supergiant’, meaning one of our largest known stars. It is a sun at the end of its life and has used up all of its supply of fuel. The light from Betelgeuse takes so long to reach us (600 years travelling at the speed of light) that we are seeing it as it was 600 years ago - in the year 1418 when Henry V was on the throne! It may have already exploded into a supernova but don’t worry, this will not endanger us on Earth as it is too far away. Interestingly, some astronomers believe during the explosion the brightness could be as great as our Moon for a short period.
All of the other main stars that make up Orion are young blue stars. The bottom right of the figure as you observe is called Rigel. Orion’s belt is the three stars at the centre of the constellation. This ‘belt’ has a sword which hangs down from it. On clear nights you will see it as a bright smudge. It is made up of gas and dust and is called a Nebula. This is where new stars are born. I have included an image I took of the Orion Nebula taken from Embsay on December 15th 2017.
Your challenge this month is to find Orion then his shield and weapon above him. It won’t be difficult to spot the supergiant Betelgeuse.
A harder challenge is to spot Orion’s Nebula. Good luck!
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