Archive for November, 2012

These last few weeks has heralded the welcome return of a dear old friend, and on Guy Fawkes evening I finally got the chance to see him for the first time this year.  As the wispy spectres of dying bonfires hung low in the autumn air, the cold, crisp, cloudless night sky was unveiled in all of its grandeur, and there, standing valiant on the south-western arc of the celestial equator was Orion.

The hunter: his club held high in his right hand, a lion’s skin draped on his left.  Flanked by his hunting dogs Canis Major and Canis Minor he traverses the skies, perpetually battling the charging bull, Taurus (or relentlessly pursuing Lepus the hare, depending on your reading of the myth).

Image   Orion is, by far, the most recognisable constellation in the night sky.  Unlike most of the other constellations, it doesn’t take the amateur stargazer several moments to link point-of-light to point-of-light to uncover the form and shape; he stands out from the others with striking clarity.  The stars Alnitak, Alnilam and Mintaka form his almost horizontal belt.  His sword is the home of a beautiful nebula. Upon his feet he wears the stars Rigel and Saiph, and his shoulders carry the stars Bellatrix and Betelgeuse.

Betelgeuse is a star of particular interest.  If you were to look at Betelgeuse through a telescope or even with the naked eye you would notice one thing: its colour.  Betelgeuse is red.  It is red because of the type of star that it is: a red supergiant.

Betelgeuse is around twenty times the mass of our Sun, and if it was to replace the Sun at the centre of our Solar System, it would extend out to Jupiter, engulfing us and everything else in its wake.

The other thing of note about Betelgeuse is that it is dying.  This unimaginably vast and beautiful star is entering the final stages of its life.  At only 10 million years old it is still a relatively young star (compared to our sun, which is nearly 5 billion years old with another 5 billion to go), but because of its immense size it has sped through its life.  And when it goes, it will not go quietly.  Betelgeuse will shuffle off this mortal coil as a supernova.  And because it is only around 500 light years away it will present us with quite a show.Image

When Betelgeuse goes supernova, it will shine in our skies as bright as the moon and will probably be visible during the day (although not in a Tatooine binary sun way).  In that single instance of stellar explosion, Betelgeuse will release more energy than our sun will produce in its entire lifetime.  This display will remain in our skies for approximately 2-3 months before dimming.

So, when will this happen?  Well, by current estimations, anytime soon.  But when is ‘soon’?  Well, soon could be anytime from tomorrow morning to the next million years.  Betelgeuse is ready to blow!  However, stellar time scales do not take into account human impatience, or human lifetimes, or even human existence.  Also, let’s not forget that, if tomorrow is S-Day (Supernova) for Betelgeuse, we won’t see the resulting spectacle until sometime around the 25th century due to the distance of the star and the speed of light.  So unless the event happened in and around the 16th century, we might be in for a bit of a wait.

The last supernova visible from Earth occurred in 1604, before the invention of the astronomical telescope.  We should also, theoretically, get at least one supernova per galaxy per century.  But we’ve not had the good fortune to witness such a spectacle on terra firma for over 400 years.

There is another reason why there is great importance in the death of Betelgeuse, or any other star in its final throes, or, for that matter, any other star in the Universe.  They are the origins of life; we were forged in the hearts of dying stars.

Stars, such as our Sun, are fuelled through the nuclear fusion of hydrogen into helium, which releases vast amounts of energy allowing the star to generate heat and light.  As the star reaches its twilight years and begins to run out of its hydrogen fuel, the battle between nuclear fusion and gravity begins to give way in favour of gravity.  The star then begins to collapse in on itself.  As this happens, the star becomes an alchemist.  Within the increasing heat and density of the collapsing star, nuclear fusion goes beyond simple hydrogen to helium combinations.  More complex atoms begin to fuse together, including carbon and oxygen and many more.  When the star finally gives in to its cataclysmic death, these elements are then violently distributed throughout the universe, forming clouds of dust and gas, clumps of rock, planets, organic material; us.

All living and non-living things with mass are made up of a variety of atoms, and those atoms were forged within the fiery hearts of dying stars.  We are stardust!  It’s a very hippy thing to say, but it’s true.  Although, I think that theoretical physicist Lawrence Krauss said it better:

“Forget Jesus!  The stars died so that you could be here today!”

Ever since I was a little biddy boy I have loved the stars, the planets, the universe, and I have always greeted the appearance of Orion with joy.  Orion arrived with the falling of the leaves, the snow and with Christmas; what better friend for a kid!

What better friend for a Universe that has the potential to harbour life than a star that, after eons of lighting up the cosmos, makes the ultimate sacrifice in order to fill the void with the materials for creation.

So next time you see Orion, look at the red twinkle on his right shoulder and give a dying old man a smile.

John

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