ARLA/CLUSTER: Prevista boa chuva de estrelas para as Perseidas deste ano (200 meteoros por hora).

[João Gonçalves Costa]

[http://tbn2.google.com/images?q=tbn:LQW2a5N-Mo87nM:http://1.bp.blogspot.com/_IoU3bEFUwWc/SIYmQzpdJAI/AAAAAAAACdw/04Cz9aGKjls/s400/Perseid%2BMeteor%2BShower.jpg]<http://images.google.pt/imgres?imgurl=http://1.bp.blogspot.com/_IoU3bEFUwWc/SIYmQzpdJAI/AAAAAAAACdw/04Cz9aGKjls/s400/Perseid%2BMeteor%2BShower.jpg&imgrefurl=http://philosophyofscienceportal.blogspot.com/2008/07/perseid-meteor-shower-2008.html&usg=___Df2r22tyVDeiNXyv-l9pyU5oFE=&h=400&w=361&sz=60&hl=pt-PT&start=70&tbnid=LQW2a5N-Mo87nM:&tbnh=124&tbnw=112&prev=/images%3Fq%3DPerseid%26gbv%3D2%26ndsp%3D20%26hl%3Dpt-PT%26safe%3Dactive%26sa%3DN%26start%3D60>
Perseid Meteor Outburst

POSSIBLE PERSEID OUTBURST: This year's Perseid meteor shower could be even better than usual. "A filament of comet dust has drifted across Earth's path and when Earth passes through it, sometime between 0800 and 0900 UTC (1 - 2 am PDT) on August 12th, the Perseid meteor rate could surge to twice its normal value," says Bill Cooke of NASA's Meteoroid Environment Office. The following profile is based on the debris stream models of veteran forecasters Jeremie Vaubaillon and Mikhail Maslov:

[http://spaceweather.com/swpod2009/04aug09/Per009_zhr_strip.jpg]<http://spaceweather.com/swpod2009/04aug09/Per009_zhr.jpg?PHPSESSID=hqli6p64sqkshu7eslfv6lvia5>

The filament was shed by Perseid parent comet Swift-Tuttle in the year 1610, and this is one of Earth's first encounters with it. "In addition," notes Cooke, "the main Perseid debris stream, which we run into every year, may be denser than normal due to a gravitational enhancement by Saturn. The total combination of these effects could result in as many as 200 meteors per hour (ZHR)."

Bright moonlight will overwhelm the outburst's fainter Perseids, but even a fraction of 200 is a good show. Science  NASA's "The Perseids are Coming<http://science.nasa.gov/headlines/y2009/31jul_perseids2009.htm>" offers observing tips and sky maps.

Perseids on your iPhone:
Spaceweather.com is pleased to announce a new iPhone/iPod application dedicated to the upcoming Perseid meteor shower. It features a Perseid countdown clock, news alerts, an easy-to-use sky map, and a live gallery of photos from around the world. Sky watchers of all types will find it a valuable companion when the shower peaks later this month.

Learn more: http://spaceweather.com/perseids

Download the app: http://itunes.apple.com/WebObjects/MZStore.woa/wa/
viewSoftware?id=325305245&mt=8

Fonte: Science  NASA's
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