Under The Martinborough Stars

Another glorious Martinborough summer is here! I’m expecting red hot days, jumping in cool blue water and drinking a delicious Martinborough chilled white wine while enjoying a warm orange sunset around the amber glow of a fire pit.

We take colours and the associated temperature for granted. But in astronomy it all gets a bit, well confusing.

There are five main colours of star, going from red all the way to blue. Of course, there are other colours associated with astronomy; black holes, dark matter and red shift for example.

The colours of stars can tell you how old they are, how big they are and their life expectancy, what will happen to them when they die and how far along in their lives they are.

A quick reminder for anyone who has drunk too many Martinborough wines already, stars create heat and light by combining simple elements in their core. Our yellow Sun is busy changing hydrogen into helium and a little sprinkling of carbon, nitrogen and oxygen to boot.

Common red stars, or small red dwarfs are the most abundant coloured star in our Universe and can live a very long time. Their reduced size means they can burn slowly and gradually, even reaching trillions of years old.

We also have Red Giants, a totally different type of star. These are stars that are huge and are cooling down because they are coming towards the end of their lives. They were once massive blue stars and are doomed to end in a supernova once gravity takes over and the star can’t keep itself together any longer. A good example of a soon-to-supernova-red-giant is Betelgeuse in Orion. You can find it under the Pot. It is due to supernova in the next million years or so, and when it does you should be able to see it in the daytime sky, as bright as the full moon.

Blue stars are the rock stars of the sky; they live fast and die young. Extremely hot, they plough through their hydrogen quickly and are huge. Blue stars have to be at least 3 times the mass of the Sun to produce the heat required to shine as blue. Look again at Orion, but this time the bright blue star Rigel above the Pot. Rigel is over 10,000 degrees C on the surface compared to our yellow Sun’s 5000 degrees C and Betelgeuse is a cool 3,500 degrees.

Next time you are having a red hot bath or a cool blue ocean dip, just remember that a stars colour and temperature is the opposite to what you would normally think about.  

Happy New Year to all you Martinborough Star Readers. Why not make your new year’s resolution to go outside and look at the stars a bit more often?

I’m going to enjoy another chilled Martinborough white wine. 

Becky runs Under The Stars, a nomadic and award winning astro-tourism business in the Wairarapa.