Bring me Sunshine …

October 16, 2019
Sunset above the clouds

What colour is our sun?

Living in Tenerife the effect of the sun on the Earth is evident daily.  We almost take it for granted, albeit as I write this there is a big black cloud over head.  Nice change to the temperature for us locals but not so great for the holiday makers.  On our tour we talk about the basic life of a star or as is our own sun.  So today I thought we would look more closely at the suns of our galaxy!

White Sun
Our Sun looks white from space.

If you ask 90% of people what colour the sun is, you will either get laughed at for asking a stupid question or told its yellow.  In fact, our sun is a complete mixture of colours making it appear to our eyes as white!  It is only our atmosphere that makes it appear yellow in the sky.  This is most evident from pictures taken outside of our atmosphere.

So, what types of stars are there?  Well stars are about as diverse as anything else in our universe.  In truth, there are many different types of stars, ranging from brown dwarfs to red and blue supergiant’s and there are even more bizarre kinds of stars in between, like neutron stars and Wolf-Rayet stars.

Our Sun is a main sequence star, as are most of the stars in our galaxy and the known Universe.  Our two closest neighbours Sirius and Alpha Centuri A are main sequence stars too.  Although these stars can vary in size, mass and brightness, they are all doing the same thing.  They all convert hydrogen to helium in their cores, releasing a tremendous amount of energy.


Our sun is the pixel you cant see next to the binary stars Albireo

A star in the main sequence is in a state of hydrostatic equilibrium.  Gravity is pulling the star inward, but the light pressure from all the fusion reactions are pushing outwards.  The two forces balance each other out and the star maintains a spherical shape.  Stars in the main sequence will have a size that is determined by mass which defines the amount of gravity pulling them inward.

To ignite a main sequence star, you need a minimum amount of 0.08 times the mass of our sun or about 80 times that of Jupiter.  A star could theoretically grow to more than 100 times the mass of our Sun.


comedy show red dwarf
Red dwarf crew

We have spoken about white dwarfs before but what about red dwarfs?  Not just a hilarious comedy show.  In fact, Red Dwarfs are amongst the most common stars in our known Universe.  They are main sequence stars, but they have such a low mass they remain much cooler than stars like our own sun.  They have the ability to keep the hydrogen fuel mixing in their core, so they can conserve their fuel for much longer than other stars.  Some astronomers say that these are the most efficient of stars and even estimate that these stars could potentially burn for as long as 10 trillion years.  The smallest of red dwarfs are 0.075 times the mass of the Sun or up to 50% the mass of our Sun.

The largest of stars in our galaxy are Supergiant’s.   These stars can have masses more than dozens of times that of our sun and are the Monsters of the Universe.  Supergiant stars are burning hydrogen at an enormously high rate and can consume their fuel within a few million years.  Supergiant’s live fast and die young.  When they are in the final stages of their life they often detonate as supernovae, completely disintegrating themselves in the process.

So, as you see, suns (stars) can come in all shapes and sizes, colours and varieties.  Knowing about the life cycle of stars and how they are formed and behave is essential to us beginning to understand how our universe works and the future exploration of our own galaxy, not to forget the continued search for life outside of our solar system.

sunset with cava
Cava on the Sunset & Stars Tour.

To learn about our own sun and it´s predicted fate, join us on a sunset and stars tour!

For now though this Kieran signing off.


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