Thursday, 8 August 2013

Shooting Stars - See The Perseid Meteor Shower on Monday 12th August/Tuesday 13th August

Meteor (probably not a Perseid) & comet Hale Bopp
Credit: Your Humble Editor
All around the globe keen star-gazers are gearing themselves up for a special annual event. No, it's not the Huttons Ambo Produce Show, splendid as it is: it's the Perseid Meteor Shower.

What in tarnation is that, I hear you cry? Well, every year the earth passes through a thin trail of dust and rocks left  in the wake of a comet (which goes by the unlikely name of Comet Swift-Tuttle).  Like all comets, Swift-Tuttle is a poor driver: it cuts across the orbits of the planets and as a result we cross its dust trail every August. This shower of gritty dust is moving pretty fast: when it hits the atmosphere its doing 60 kilometres per second. That’s 37 miles per second in old money. Call it 130,000 mph.

The result is near instantaneous vaporisation of the dust. Each particle hitting the atmosphere produces a brilliant streak of light that we call a shooting star.
Perseid Meteor over the European Southern Observatory Very Large Telescope. 
Credit: ESO/S. Guisard (www.eso.org/~sguisard)
There are many annual showers of shooting stars but the Perseid shower is without a doubt the best and most spectacular of them all. The shooting stars are fast, brilliant white and they often leave a faint smoky trail behind them that fades in a second or two. Occasionally one will burst into red fragments and very rarely you might have the good luck to see a fireball – a brilliant shooting star as bright as a firework rocket.

As I write (8th of August), we’re already in the edge of the dust stream, if you go out tonight, after dark, you might see one or two bright shooting stars coming out of the North East. But Monday and Tuesday nights are Jackpot nights: we hit the centre, near enough, of the dust stream. If you go out on the nights of the 12th or 13th you might see shooting stars arriving at the rate of one a minute. But if you want to do that you need the advice of an old hand, fortunately I am here to help you:
  • First of all the sky has to be dark and free from clouds. Get away from street lights – not a problem in Huttons Ambo – but you may want to switch off any security lights temporarily or go to a part of your garden where you won’t trigger them.
  • You need to find a spot with a view of the North East - but Straight Up will do in a pinch.
  • Wait until at least 1045pm, the sky needs to be properly dark.
  • Wrap up warm. I can’t tell you how important this is, even a balmy August evening can turn pretty cold by 11pm.
  • Ideally, to avoid getting a stiff neck, lie on a sun-lounger, facing North-East/East.
  • Now your eyes need at least fifteen minutes to get properly dark-adapted. I really mean that, fifteen honest minutes, not three minutes of muttering “I can’t see anything” and then going back inside to catch up on the East Enders. This is better than East Enders. So switch off your torches, relax and see how many stars you can count over the next fifteen minutes.
  • Once you've become dark-adapted, give me another fifteen minutes of honest sky-watching and I promise you that you’ll see at least half a dozen brilliant and fast shooting stars.
  • Bonus points for the dedicated: if you really persist, say for an hour or so, you might also see some faint shooting stars coming from the South. There are at least two other weaker shooting star showers active at the moment, one of which has a reputation of producing the occasional spectacular fireball.
What if it’s cloudy on the night? Well the shower splutters on over the next couple of weeks, so don’t think these nights are the only time to see them, you can look out on other nights but you’ll have to be patient – the rate of shooting stars falls off quite quickly after the 13th.

Good hunting!

All material © Philip Stone 2013

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