August 112009
2009 Perseid Meteor Shower Information
The annual Perseid meteor shower, has been viewable for sometime now. But tonight, they are expected to be at their peak, with as many as 110 meteors streaking the Northeastern sky hourly.
Credit: Science.Nasa.gov
Look for them throughout the night tonight, but promising times are as early as 9 p.m. and peaking around 1 a.m. PDT.
Just before the first rays of Wednesday, you may see “dozens” of the shooting stars. The 9 p.m. to 1 a.m. window, though, is when you should watch for what astronomers call “earthgrazers,” which may make up for their lack of frequency with their memorable good looks. Per bill Cooke of NASA “meteors that approach from the horizon and skim the atmosphere overhead like a stone skipping across the surface of a pond”. “They are long, slow and colorful — among the most beautiful of meteors.”
Perseid Frequency per hour
per Spaceweather.com “watchers in dark country locations could see more than 100 meteors per hour, and perhaps as many as 200 if Earth passes through an anticipated filament of comet dust that is crossing Earth’s path.”
Additional Information of the Perseids per Space.com:
We know today that these meteors are actually the dross of the Swift-Tuttle comet. Discovered back in 1862, this comet takes approximately 130 years to circle the sun. And in much the same way that the Tempel-Tuttle comet leaves a trail of debris along its orbit to produce the spectacular Leonid Meteors of November, the Swift-Tuttle comet produces a similar debris trail along its orbit to cause the Perseids.
Indeed, every year during mid-August, when the Earth passes close to the orbit of Swift-Tuttle, the material left behind by the comet from its previous visits, ram into our atmosphere at approximately 37 miles (60 kilometers) per second and create bright streaks of light in our midsummer night skies.
And according to two meteor researchers, each working independently, 2009 could turn out to be an unusually intense Perseid year.
Mikhail Maslov of Russia has determined that within a matter of several hours on the morning of Aug. 12, the Earth will come close to three trails of dust shed by the Swift-Tuttle comet from three prior visits to the vicinity of the Sun (in 1610, 1737 and 1861). All three encounters will all occur within a roughly 4-hour time frame between 4 and 8 hours UT, which will be particularly favorable for eastern North America where this interval corresponds to midnight to 4 a.m. on Aug. 12; the constellation of Perseus will be gradually climbing the northeast sky during this time frame.
According to Maslov, the Earth will be passing only 87,000 miles (140,000 km) from the center of the 1610 trail at 8:07 UT (4:07 a.m. EDT).
In the absence of moonlight, an observer might see up to 200 meteors per hour around that time, a number that sadly – because of the bright moon – won’t in 2009. Overall, though, the Perseids might still put on a good display despite the interfering moonlight, with at least the brighter meteors being visible to patient observers.
Another researcher, Jeremie Vaubaillon of Caltech, used a computer simulation to depict Earth’s passage through the Perseids in 2009. Vaubaillon’s simulation clearly shows Earth encountering significant meteor activity from about 0 hours UT on Aug. 12 through about 6 hours UT on Aug. 13, possibly suggesting better than average Perseid activity worldwide for both the late-night hours of Aug. 11 and Aug. 12, local times.
Additional Links: Perseid Google Search
