Perseid meteor shower

Weekend Diversion: The Best Falling Stars of the Year

esiegel — Sat, 11 Aug 2012 09:33:05 +0000

Weekend Diversion: The Best Falling Stars of the Year

"Stuff that's hidden and murky and ambiguous is scary because you don't know what it does." -Jerry Garcia

Earlier this month, one of my favorite musical artist of all-time would have turned seventy. This weekend, I'm off at a fantastic music festival where they're celebrating the life of Jerry Garcia, and in addition to being the leader of the Grateful Dead, he was also a huge influence in the world of bluegrass, americana and folk music. While I always loved his songs about lovable scoundrels, here's a duet of him with David Grisman performing the much more pastoral

Shady Grove,

and there's maybe no better song to listen to while we talk about the best meteor shower of the year -- peaking tonight -- the Perseids!

Image credit: Peter Meadows, British Astronomical Association.

While the first Perseid meteors started showing up back on August 4th, the Perseids will peak tonight, and anyone with clear skies, even in cities, should be able to enjoy them.

Here's a quick guide.

Image credit: created by me using Stellarium, available free at http://stellarium.org/.

Almost everyone in the Northern Hemisphere can recognize the Big Dipper (at left on this image), the North Star (Polaris), and Cassiopeia (the big W towards the right), all of which are visible in the north throughout the night.

Just beneath the first V in Cassiopeia's W is the famous Double Cluster in Perseus, one of the most spectacular collections of hot, young stars in the nearby Universe.

Image credit: Roth Ritter of Dark Atmospheres (http://www.darkatmospheres.com/astro/).

Although it's visible to the naked eye under very dark skies, it's most spectacular through telescopes or very good binoculars. But it isn't the Double Cluster itself that's important tonight; it's the location of this area of our night sky.

Image credit: Chris Cook 2002, originally taken on November 27th, 1992.

Every 133 years, Comet Swift-Tuttle passes through our inner Solar System, coming just inside of Earth's orbit. It's been doing this since at least 69 BC, and passed through most recently in 1992.

Image credit: Gehrz, R. D., Reach, W. T., Woodward, C. E., and Kelley, M. S., 2006.

Like all comets, Swift-Tuttle leaves a debris trail through the Solar System throughout the path of its orbit. When the Earth passes through this comet trail, the particles of cometary dust strike our atmosphere at somewhere between 20-25 kilometers per second, creating what we see on Earth as a meteor (or a shooting star).

Image credit: Ron Garan, ISS Expedition 28 Crew, NASA.

That's where this meteor shower comes from, so where and when should you look to see it?

Well, let's go back to Cassiopeia to see where all of these meteors appear to come from.

Image credit: me, created with Stellarium and some basic image editing.

Although Cassiopeia should be low on the horizon in the early part of the night (around 10 PM), rising higher throughout the night, you're in luck for two reasons.

First, the Moon is only about 1/3 full and waning, meaning that it won't even appear in the sky until after midnight. As the greatest source of light pollution, your best bet is to watch for meteors before the Moon rises. But second is that the Perseid meteors are fast, so that the entire sky is up-for-grabs when it comes to where you're going to see one! Even though Cassiopeia will be higher in the sky as the night goes on, the Perseid meteors are so fast-moving that they tend to streak over large areas of the sky, although I'd still look (roughly) towards the North.

In fact, this composite image of a whopping 253 meteors from the 2007 Perseid shower illustrates just how far the Perseids can extend.

Image credit: Fred Bruenjes.

The best time for observing is as late as possible before the Moon rises high, so between about 11 PM and 1 AM tonight. The peak rate of meteors is estimated to be about one meteor per minute, so simply look towards the North (not directly at the radiant, as the meteors will all be moving away from that point), and enjoy it!

For those of you with either cloudy skies or in an inopportune location to watch, check out the NASA live stream (with picture resources) of the 2012 Perseids, and whatever you're doing, enjoy your weekend and enjoy the skies tonight!

esiegel Sat, 08/11/2012 - 05:33

Check out the Famous Perseid meteor shower

kcollins — Wed, 11 Aug 2010 08:00:00 +0000

Check out the Famous Perseid meteor shower

Star light Star bright first star I see tonight... One thing I love about camping and getting away from the city is looking up into the night sky and seeing the vast array of stars that populate the sky. I am always amazed by how bright and how MANY stars twinkle up there, but one of the more exciting things I love to look for are 'shooting stars.' And it looks like we are in for quite a show of shooting stars! One of USA Science and Engineering Festival partners, EarthSky, reminded us that the famous c that will be taking place this week. So take some time to look up at the night sky and look for a shooting star....or two.

More information on the meteor shower from our Festival partner:

The 2010 Perseid meteor shower - August's famous 'shooting stars' - will peak in this coming week, on the mornings of August 12 and 13. The shower has been gradually rising to a peak since early August. Any night this week, you might see Perseid meteors.

The Perseids are considered by many people to be the year's best shower. They often peak at 50 or more meteors per hour, and 2010 is a great year for watching them. This year, the slender waxing crescent moon will set at early evening, leaving a dark sky for this year's Perseid display.

Remember, this is August 12 or 13 in the hours after midnight - not those evenings. The Perseids tend to strengthen in number as late night deepens into midnight, and typically produce the most meteors in the wee hours before dawn.

These meteors are often bright and frequently leave persistent trains. On the mornings of August 12 and 13, watch the Perseid meteors streak across this short summer night from midnight until dawn. Lie back and watch meteors until dawn's light washes the stars and planets from the sky. The morning of August 11 may be good, too - in fact, this shower tends to rise gradually to a peak for about a week. Then it's known to drop off rapidly after the peak mornings.

These typically fast and bright meteors radiate from a point in the constellation Perseus the Hero. But you don't need to know Perseus to watch the shower. The meteors appear in all parts of the sky.

How to find the radiant point of the Perseid meteors

Tips for watching meteors

Most important: a dark sky. Here's the first thing - the main thing - you need to know to become as proficient as the experts at watching meteors. That is, to watch meteors, you need a dark sky.

Know your dates and times. You also need to be looking on the right date, at the right time of night. For the Perseids, the best time is midnight to dawn on the mornings of August 12 and 13. But you might also see Perseids before those dates, since the shower builds to a peak gradually. Afterwards, it falls off rapidly. The nights before the Perseid's peak are probably better for meteor-watching than the nights afterwards. Meteor showers occur over a range of dates, because they stem from Earth's own movement through space. As we orbit the sun, we cross "meteor streams." These streams of icy particles in space come from comets moving in orbit around the sun. Comets are fragile icy bodies that litter their orbits with debris. When this cometary debris enters our atmosphere, it vaporizes due to friction with the air. If moonlight or city lights don't obscure the view, we on Earth see the falling, vaporizing particles as meteors.

What to bring. You can comfortably watch meteors from many places, assuming you have a dark sky: your back yard or deck, the hood of your car, the side of a road. If you want to bring along equipment to make you more comfortable, consider a blanket or reclining lawn chair, a thermos with a hot drink, binoculars for gazing along the pathway of the summer Milky Way. Be sure to dress warmly enough. Even the summer nights can be chilly, especially in the hours before dawn when the most meteors should be flying.

Are the predictions reliable? Although some have tried to publish exact predictions in recent years, meteor showers remain notoriously unpredictable. Your best bet is to go outside at the times we suggest, and plan to spend at least an hour reclining comfortably while looking up at the sky.

Remember, meteor showers are like fishing. You go, you enjoy nature ... and sometimes you catch something!

Image Credit: A Perseid meteor from the 2009 shower, by Kevin Clifford (AP)

kcollins Wed, 08/11/2010 - 04:00