Mark your calendars for late night August 12, then stake out a spot to skywatch that has low light pollution. This year’s Perseid meteor shower is expected to put on quite a show. According to http://www.space.com/, Perseid meteoroids (what they’re called while in space) are fast, entering Earth’s atmosphere (and are then called meteors) at roughly 133,200 mph (60 kilometers per second) relative to the planet.

Most are the size of sand grains; a few are as big as peas or marbles. Almost none hit the ground, but if one does, it’s called a meteorite.

The Perseids are created from debris from the comet Swift-Tuttle, the largest object known to make repeated passes near Earth. Its nucleus is about 6 miles across, roughly equal, says space.com, to the object that wiped out the dinosaurs.

More than a decade ago, an astronomer calculated that Swift-Tuttle might hit Earth on a future pass – a prediction now discounted – although it’s believed there may be a cosmic near miss (about a million miles) in 3044.

We see shooting stars when a Perseid particle enters the atmosphere, compresses and heats up the air in front of it. The meteor, in turn, can be heated to more than 3,000 degrees Fahrenheit (1,650 Celsius). Most meteors are vaporized in the intense heat, creating what we call shooting stars, which become visible at about 60 miles up. Some large meteors splatter, causing a brighter flash called a fireball, with an explosion that can often be heard from the ground.

Overnight, between Aug. 12 and Aug. 13, stargazers should see dozens of shooting stars each hour in a moon-free dark sky. During peak times, the meteor shower should produce one or two visible streaks every minute. In rural areas, watchers may see as many as 100 an hour.

According to NASA (http://www.nasa.gov/), beginning around 9 p.m. Aug. 12, a handful of “earthgrazing” meteors may skim the northeast horizon, described as long, slow, colorful and among the most beautiful of meteors. As Perseus rises, the meteors rise higher in the sky, and are best observed with the naked eye because they will move so fast.

To view last year’s meteor shower, visit http://www.space.com/.

Carol Bogart is a freelance writer/editor. Read her blog at http://carolbogart.blogspot.com/ and her articles at http://www.hubpages.com/.   

  

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