10 August 2009

Perseid Meteor Shower 2009

It's August and that means its time for the annual Perseid Meteor Shower, this year reaching its peak on the evening and through the morning of August 11-12. Meteors are visible just about any night of the year, but throughout the year there are periods of intense activity in the sky ("meteor showers") because the Earth travels through a point in its orbit where there is a higher amount of space dust, rocks and other particles that enter the atmosphere at tens of thousands of miles per hour and burn up, creating bright streaks across the sky.

The Perseid Meteor Shower is going to be harder to see in 2009 because of the bright Moon that rises at 10:40 pm in San Francisco. For the city dweller, however, the shower is not much worse because of the bright Moon, as our city lights obscure many meteors anyhow. So the best you can do is simply enjoy the shower the evening of August 11th from wherever you are in the city. Pick a darkened comfortable spot. Lay back on a blanket and point your feet to toward the north-east and look around the sky. As the evening wears on, the origination point ("radiant") of the meteor shower rises in the north-east. This area is near the constellations Perseus and Cassiopeia as shown in the illustration to the right.

This year there will be a possible jump in the number of meteors as the Earth passes through a denser-than-usual filament of dust from the remnants of comet Swift-Tuttle. That will happen around 1:00 am pacific time on the 12th, so if you are up late you might just see a more intense period of meteor activity. Throughout the entire evening, the Moon will remain the one bright light everyone cannot escape, so when it rises just point your gaze in another direction and keep your eyes on the sky. And stay warm!

If you want to see a good meteor shower this year that won't have moonlight in the way, look ahead to December 14th when the Geminids will peak at an even higher rate than the Perseids. However it will be considerably cooler and the weather is less predictable at that time.


Peter Corless said...

Paul, I heard your interview on KFOG this morning. You were asked about what the religious significance of meteor showers were. There weren't many, per se, but there was a pseudo-scientific or supernatural explanation of what a meteor was.

Check out this link:


Aristotle of Stagira, c. 4th Century BCE, was credited with Greek philosophical view of saying that meteors were a form of "fire element" ejected from the earth up into the sky. Originally, meteors were thought somewhat akin to lightning.

(Of course, meteors are falling bits of minerals from outer space, whereas lightning is caused by electrostatic discharge in the atmosphere. But they had no way of knowing.)

This elemental belief became incorporated into early Christian era science, and was not corrected for over 2000 years, when Newton's laws of gravity and the sciences of modern physics and astronomy were finally used to prove that meteors fell from earth, rather than being some sort of "fire" element cast into the sky.

So now you have something to tell KFOG the next time you're asked!

The Urban Astronomer said...

Thanks for the info, Peter. Fascinating to get a history lesson on this - next time I'm asked, I'll say the ancient astronomers thought it was the breathing out of the elements!

Kristin said...

Great information. Thank you so much for letting us City dweller know where to look.

Bob Johnson said...

I was rained out during the peak of 11-12th but the night after I was treated to the best shower I've seen in a few years.

The Urban Astronomer said...

Hi Bob - congrats. We had bad fog on the night of the 11-12th and that was a big disappointment. However, the sky was much better the next night. Nonetheless, here under city skies I was able to see only a few. I have my sights set on the next few showers now - a lot less moon, and believe it or not, better weather prospects in November and December here in the Bay Area!

Becca said...

I sat out in my backyard the night of the 12th and saw 6 shooting stars within about an hour or so; they were gorgeous! And the light wasn't too much of an issue, although I'm just south of USF.

The Urban Astronomer said...

Awesome, Becca. As I sat out on the evening of the 12th I was again reminded just how much we can see right here in SF. Giving yourself some time is the most important part of the game. The weather is getting good now in SF. Enjoy!

Richard Cranium said...

On Aug-13 She/I spotted 87 in 70 min. Between 1:00-2:10 am.

Got clouds, went up the Mtn and from 3:30-5:00 got 81 more total of 168.

Not bad for Moon conditions and light pollution of NW Ga.

Note: We did NOT count the "I Think" ones at the edge of vision.