Somewhere in our solar system is a huge 26 kilometre (16 miles) wide chunk of rock and ice is on its 133 year long orbit around the Sun. This is the comet Swift Tuttle, an icy visitor larger than the one that is thought to have ended the party for the dinosaurs, and one that does come relatively close to the Earth and Moon. In 2126 the comet will pass by Earth at 15 million miles away, and should be a good sight similar to Comet Hale Bopp back in 1997. In the year 3044 Comet Swift Tuttle will actually come within a million miles of Earth, so far in the future that who knows where the human race will be by then.
Anyway, so what has this comet got to do with probably the best and most reliable shower of the year for northern sky watchers, the Perseids? Well, everything. As the comet moves along its orbital path it happens to leave dusty debris in its wake, small rocky grains. This is just great for us sky watchers as every August these dust grains, up to a 1000 years old, come zipping through Earth’s atmosphere as very fast bright streaks of light during the warm summer nights.
What will I see?
You might see if you apply lots of patience, up to 60 meteors per hour, or maybe more. You may well even see meteors leaving persistent trains. A persistent train makes the meteor look just like it’s leaving a smoke trail behind it, but in actual fact this is not smoke. When the small cometary dust grain hits the atmosphere it ionises the gases and strips electrons from atoms, and when the electrons then recombine with the atoms they emit light. Sometimes the meteor persistent train lasts for minutes, long after the meteor flash itself, and twists and moves as the high level winds blow it. You may if you’re very lucky also see a fireball, larger bits of rock that are much brighter than the normal meteors. The International Astronomical Union classes a fireball as being brighter than any of the planets in the sky, at magnitude -4 or brighter.
Where do I look and when?
As with most meteor showers the clue is always in the name, the Perseids mean the meteors emanate from the constellation of Perseus. Perseids meteors can be seen in any point of the sky, but a Perseid meteor’s direction will always trace back to the direction of constellation Perseus. So that is a good direction to look in for meteors, but try to take in the larger area of sky as they can appear anywhere. The Perseus constellation rises from the north east at around 10.00 pm BST on the evenings of the 11th and 12th of August. It rises quite high during the night before moving towards the east by daybreak.
The Perseids meteor shower peak is known to be the dates of the 12th and 13th of August. This actually means the 11th and 12th beyond midnight and during the pre dawn hours, as this is when you’re likely to see more and faster meteors. This is because after midnight the Earth is moving into the meteor stream. So Perseids can be seen in the hours up to midnight, but the best views may be had if you can stay up until the small hours.
The Moon can be a fantastic object to observe through your binoculars or telescope, but during a meteor shower nobody wants it. The Moon is definitely an unwelcome visitor to your meteor watching party, as like a huge search light in the sky its glare wipes out all but the brightest of meteors. Well you’ll be glad to hear that during this this year’s Perseids it won’t be around to bother us, because as night falls and Perseus rises in the north east, the waxing crescent Moon will be setting in the west. This leaves dark moonless nights for the shower peak, just perfect for seeing meteors.
It’s always worth getting out and looking upwards during the few nights leading up to the peak of the 12th and 13th, and the nights afterwards as the Perseids span from July the 17th up to August the 24th. You may well see Perseid meteors on either side of the peak, although in lower numbers. Though not all meteors you see will be Perseids, the way you know is to trace back the direction in which the meteor came in. If it came from the direction of Perseus it will likely be a Perseid, if it came from a completely different direction it will be a sporadic meteor.
Where to look…towards the NE/E after dark.
When…The evenings of the 11th and 12th of August after dark, and beyond midnight into the pre dawn hours.
Shower rate…60 or more meteors per hour
Here is a video to inspire you, it’s by Kenneth Snyder and is footage of the Perseids Meteor Shower 2012 captured at the Sleeping Bear Dunes National Lakeshore, Michigan.
This video was captured with Canon 5D Mark III and Canon 5D Mark II and edited with Adobe Premiere and Adobe After Effects at 4K (4096×2304) resolution, four times greater than regular 1080p HD. www.unifiedphoto.com/sleepingbeardunes
So good luck with the Perseids, take out a deck chair, a hot drink, invite some friends and look up.
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