Catch the Falling Stars: Perseid Meteor Shower 2013
SLATE
Posted
Friday, Aug. 9, 2013, at 10:30 AM
The Perseids put on a fine show over Denver in 2012 as seen from Mt. Evans.
Photo by Thomas O'Brien, used by permission
Photo by Thomas O'Brien, used by permission
Every year around August 11 – 13, the Earth plows through the
interplanetary debris left behind by comet Swift-Tuttle. As we ram into
this cloud of tiny particles, they plummet through our atmosphere and
burn up in an ephemeral and lovely streak of light called a meteor.
This year should be a good show; the Moon sets early, so dark skies
will prevail. I have a guide I wrote for last year’s shower that still
applies, so I’ve reposted it here. I’m in Australia right now, and it’ll
be hard to get away from city lights to see them. So go out and watch
them for me, OK?
How To Watch The Perseid Meteor Shower
The annual Perseid meteor shower peaks over the next few nights
(typically around August 12), so this is the best time to go out and
look. I have a guide on how to observe the shower and a couple of links,
too, but first indulge me a moment to talk about meteor showers.
The Earth orbits the Sun, as do comets. Comets are lumpy collections
of gravel and dust held together in a matrix of frozen ice (usually
water and/or carbon dioxide). As they get near the Sun, the ice turns
into a gas, freeing the dust and gravel. This material follows in the
same path of the comet like dirt flying off a dump truck on a highway.
Over time - millennia - it spreads out into space.
The Earth plows into this stuff as it goes around the Sun. These tiny
bits of cosmic jetsam burn up as they ram into our atmosphere at speeds
of up to 100 kilometers per second, and we call them meteors.
Quick tip: a meteoroid is the solid bit of rock or whatever that travels through space. As it burns up in our air we call it a meteor. If it hits the ground, it's called a meteorite. Now you can sound pretentious and correct people at cocktail parties!
The Earth is always being bombarded by meteors; about 100 tons per
day burn up in the atmosphere. But that number goes up when we pass
through the stream of matter that's come off a comet - think of it as
driving down a road and hitting the occasional insect. Then you pass
near a creek and suddenly you slam into a swarm of bugs.
So yeah, meteor showers are the equivalent of that. But much prettier and less disgusting.
Every August the Earth passes through the debris from the comet Swift-Tuttle, forming the Perseids meteor shower.
Yes, this picture is real; I took it myself in Sarasota, Florida.
Photo by Phil Plait
Photo by Phil Plait
They're called the Perseids because they appear to come from the sky
in the constellation of Perseus. It's a bit like when you drive through a
tunnel and all the lights on the sides appear to be moving away from a
point ahead of you. It's perspective, an illusion of sorts. In this
case, the orbits of the Earth and the meteoroids add together to make
the meteors appear to shoot away from the part of the sky where Perseus
is. Other showers do this too, but from different parts of the sky, and
the showers are named after their constellation. Thus, the Leonids, the
Orionids, the Taurids, and so on. The Perseids are one of the best of
the year, with about 50 - 60 meteors per hour visible (so on average one
per minute at the peak). You may see fewer than that, but sometimes
there are mini-peaks where the number goes up. It's worth going out for
an hour or two to see them!
So here's a very quick rundown of what you need to observe the shower (Universe Today has a good, short guide as well):
1) Find a place that's dark. Some meteors are bright
and easy to spot, others fainter. The darker the spot you find away
from house and city lights, the better.
2) You don't really need to face Perseus (to the
northeast); in fact your best bet is to have as much sky visible as
possible. The more heavenly real estate you can see, the better your
chances of seeing more meteors.
3) Be outside after local midnight - literally,
halfway between dusk and dawn. The geometry of the shower makes it more
likely to see meteors at that time. To use the car and bugs analogy
again, you see more splattered arthropods on your front windshield than
the rear one because you're driving forward into the swarm. After
midnight, you're on the part of the Earth facing into the direction of the Earth's travel around the Sun, so you'll see more meteors then.
A great place to watch a meteor shower is...from space! In 2011 astronaut Ron Garan took this picture of a Perseid below him as he orbited in the International Space Station.
Photo by NASA
Photo by NASA
4) Relax! Use a lounge chair or some other
comfortable way to lie out. You want to be facing up, and the more
comfortable you are the better. A blanket might help; even in the summer
a little warmth can be nice. You won't see streaks across the sky every
which way like the heavens are falling; you'll see a meteors on average
once a minute or three. So you need patience - which is rewarded when
you see that bit of light zipping across the sky. It's quite a thrill.
5) Look up! You don't need a telescope or binoculars
or other fancy equipment. In fact, you're less likely to see meteors if
you're looking through an eyepiece. Remember, the more sky you see the
better.
6) Taking pictures of meteors is easy if you only
have an inexpensive camera and a tripod. Set it up, point it anywhere
you want - find a nice collection of bright stars if you prefer - and
let it expose for a few minutes if you can. You'll have a lot of shots
of star trails and nothing else, but if fortune favors you, you'll find a
nice bright streak or two in some of the pictures. Meteors!
7) Got wireless? Then bring your mobile device outside with you and listen to the meteors, too! This is actually totally cool, and I highly recommend it.
That's it! If you want a bit more info, I wrote a guide to Perseid observing back in 2007 that's still a good synopsis of the situation, too. And again check Universe Today for more.
Meteor showers are a wonderful event, a time to relax and look up.
It's a good way to hang out with friends and family, and share the
Universe with each other. What could be better?
0 Comments:
Post a Comment
<< Home