Stargazing

Written by Stuart Revnell No Gravatar

When I was younger, I used to be hugely into stargazing and astronomy.  I could spend hours with my binoculars looking up at the night sky, and for a long time, I wanted to be an astronomer.  I even persuaded my dad to take me to a local astronomy club in Haywards Heath one night for their monthly meeting – I don’t think he shared the same enthusiasm for it unfortunately, and to be fair, it was a little dry.

One night, though, when I was about thirteen, I was up in my bedroom with my book open to the star charts, a red T-shirt over the spotlight on my desk (infra-red light doesn’t interfere with night vision), my window open and binoculars at the ready, when I had the misfortune to be spotted by my older sister, on her way back from somewhere or other quite late at night.  She promptly told my dad the next morning, and I was probably suitably reprimanded for being up late on a school night.  The whole incident had an awful subconscious effect on me and severely stunted my development.  I failed to realise my dream of becoming an astronomer, and have rarely looked at the heavens since.

No, only joking, my dear sister!  It was, in fact, the need to spend about six years studying advanced mathematics and astrophysics which led me away from the idea of a professional career.  And the only reason I barely look at the heavens now is because I live in a top floor flat in London with a street lamp right outside it.

So I was extremely excited about our visit to the Atacama desert, which, being the driest desert in the world, and with an average of 325 clear nights per year, is the ideal place for stargazing.  Some of the world’s biggest observatories are located here, and only ten minutes out of San Pedro de Atacama is the assembly site for ALMA – a $2 billion project to build an array of 66 radio telescopes, up to 12 metres in diameter, and transport them to a 5,000m plateau, where they will begin a search for radio waves indicating the presence of star and solar system formation.

We signed up for a stargazing tour with the Space Obs, and last night we donned our warm clothes to head out to a field in the middle of nowhere, where nine telescopes were set up to point towards an assortment of stars, planets, nebulae, gas clusters and so on.  I was trying to take notes in the dark, so excuse me if some of these facts aren’t entirely accurate.  Frankly though, when you’re dealing with such massive dimensions and distances, another few billion kilometres or so are neither here nor there.

Let’s start with the basics.  There are 365 days in a year, which is 8760 hours, or 525,600 minutes, or 31,536,000 seconds.  Light waves travel at 300,000 kilometres per second, which means that in a year, they will travel 300,000 x 31,536000 = 9,460,800,000,000 kilometres.  Because it becomes fruitless to think in terms of such vast distances, we call this distance a ‘light year’.

After our sun, the nearest star to Earth is called Alpha Centauri, and this star is 4.5 light years from us.  This means that the light waves emanating from the star will take 4.5 years, travelling at 300,000 kilometres per second, to reach us.  What this also means, therefore, is that when we look at this star, we are seeing the light waves which left the surface 4.5 years ago.  So effectively, we’re looking back in time.  The star may not even exist now.  It could have blown up four years and 179 days ago, and we wouldn’t see it happening in the sky until tomorrow.

On a really clear night the human eye can make out around 6,000 stars in the sky (assuming we could see both hemispheres).  In the Milky Way, our galaxy, there are estimated to be around 400 billion stars.  In one galaxy alone.  And the size of our galaxy?  250,000 light years across.  So a light wave, travelling at 300,000 kilometres per second, would take a quarter of a million years to cross it.

Now we have that, let’s move on to a cluster of stars in the constellation of Leo.  This cluster is around 35 million light years away.  This means that the light waves from this cluster left there at around the time the dinosaurs are estimated to have died out.  They crossed the universe at 300,000 kilometres per second, and then, around 40,000 years ago, just as human beings were beginning to form the first social groups on earth, they entered the Milky Way.  They travelled across our galaxy as we discovered fire, developed language, invented agriculture and the wheel, built and destroyed civilizations, discovered gravity and electricity, invented the aeroplane and the jet engine, and finally put a man on the moon.  Then last night, they reached our atmosphere, and at around 23:26, entered the telescope, bounced off the mirror at the back, hit our retinas, and finished their journey at last.

We had nine telescopes set up to point towards, amongst other things, Saturn (the picture is of Saturn through my camera, along with one of its moons, Titan, to the right), the Large Magellanic Cloud, Sirius and Alpha Centauri.  The largest telescope was pointed into deep space, towards an area of star formation known affectionately as the “Oh my god!” cluster by the tour company.  I got why as soon as I looked into it.  There in the eyepiece was one of the most beautiful sights I had ever seen.  Bright points of light sat amongst huge swathes of gas clouds, and the whole sight was strangely frozen – stars twinkle because of the atmosphere’s effect on their light waves, but here, everything was completely still.  It was as if somebody had managed to capture the most beautiful picture they could ever see in their head.  I was looking back in time, to a view of the universe before the first human being.  To an area of the universe which, if we set out now, in a spacecraft capable of travelling at the speed of light, would take us tens of thousands of generations to reach, by which time the human race as we know it may have evolved into something beyond which we can currently comprehend.  A truly amazing, awe-inspiring experience.

To bring us back down to earth, though, and talking of things one finds difficult to comprehend, I would like to mention that Jane is currently front runner in the ‘Quote of the trip’ competition – when I brought up the stargazing company’s website and showed her the departure times for the tours, she said, “Oh cool – they run at night too, do they?”

2 Responses to “Stargazing”

  1. SarahNo Gravatar says:

    I don’t remember that incident at all!!

    And Jane – I love the comment!!

  2. JamesNo Gravatar says:

    Real cool piece. Nice writing…

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