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Fun Facts About the Perseids!

The Perseid meteor shower is named for the constellation Perseus, from where the meteors appear to originate. The Perseid meteor shower is one of the most prolific showers of the year, with an average peak rate of 50- 80 streaks per hour, in darker skies. Meteors are the visible paths of vaporizing space debris as it encounters our planet’s atmosphere.

This debris, known as meteoroids, ranges in size from dust particles to small pebbles, and occasionally larger stones. As a meteoroid enters the Earth’s atmosphere, it is heated by friction, which vaporizes the debris and causes the gases (both atmospheric and meteoritic) to glow. Most meteoroids disintegrate at about 30-60 miles above the surface, but become visible at about 40-75 miles.

Meteoroids orbit the Sun just like planets, comets, and asteroids. They travel at speeds of about 26 mps, but, when combined with Earth’s orbital speed of about 18 mps, enter our atmosphere at a velocity rate of about 44 mps. The meteoroids associated with the Perseid meteor shower enter the Earth’s atmosphere at about 37 mps. Our planet encounters space debris every day, thus meteors are actually visible all year long.

Occasionally, Earth passes through thicker patches of debris, known as streams or swarms, resulting in a meteor “shower.” Meteoroid streams, or swarms, have orbits similar to those of comets, thus are believed to be fields of comet debris resulting from a comet’s closing approach of the Sun.

The Perseid meteor shower has been associated with the ancient debris field of Comet 109/Swift-Tuttle. Comet Swift-Tuttle leaves new debris each time it passes our planet – every 130 years. This debris field has the appearance of several streams, each measuring millions of miles long.

The Swift-Tuttle debris streams are comprised of small widely-spaced particles. Most of the meteoroids are about the size of sand grains, but some may be as large as small pebbles. With a core diameter of about 26km, comet Swift-Tuttle is the largest known object, and one of the oldest comets, to regularly pass closely to our planet.

Comet Swift-Tuttle was originally recorded by Chinese astronomers in 69 BC and 188AD, but was formally discovered in 1862, by Lewis Swift on July 16, and by Horace Parnell Tuttle on July 19. Three others also independently discovered this comet: Dudley Observatory’s Thomas Simons; Antonio Pacinotti and Carlo Toussaint from Florence, Italy; and Danish Astronomer Hans Schjellerup. Comet Swift-Tuttle was “rediscovered” in 1992 by Tsuruhiko Kiuchi, ten years after its expected return of 1982.

That year, the comet reached 5th magnitude, making it easily visible through binoculars. Comet Swift-Tuttle will pass within 14-million-miles of our planet when it next returns in 2126. Scientists believe that the comet will be even brighter than the 1992 pass, and likely readily visible to even unaided eyes.

Astronomers once believed that comet Swift-Tuttle might, in the relatively near future, pass close enough to actually impact Earth or the Moon. While continued observations and recalculations have dispelled that concern for at least the next 2,000 years, this comet remains one of the greatest known solar system threats to our planet.

Source Material: NASA Worldbook JPL’s Solar System Dynamics Gary Kronk’s Cometography Astronomical Society of the Pacific Space.com Wikipedia

By Tavi Greiner. See more from Tavi at her site A Sky Full of Stars and follow her on Twitter @TaviGreiner

The Great Twitter Meteorwatch

The Great Twitter Meteorwatch

Wednesday 11th to Saturday 14th of August 2010

From Wednesday 11th to Saturday 14th of August 2010 the Virtual Astronomer @VirtualAstro with the British Astronomical Association @britastro Beyond International Year of Astronomy and amateur astronomers, will be holding a Twitter Meteorwatch for the Perseid Meteor Shower.

Everyone is welcome to join in, whether they are an astronomer, have a slight interest in the night sky or just wonder?

As well as looking up, enjoying the night sky with us and seeing meteors, maybe for the first time? You will have the opportunity to contribute to Science if you wish, by tweeting and seeing your results on a map, or by submitting Observing Forms if you are a more serious observer.

This event follows on from the popular Twitter Meteorwatch held in August and December 2009 "Meteorwatch 2009"

Use the hash tag: #Meteorwatch and get involved, ask questions, do some science, follow the event and enjoy the wonders of the night sky with us. Images and other information will be tweeted as it happens. Live!

The highlight of the summer meteor showers: The Perseids, reach maximum around The 12th of August and may put on a display of aproximately 80 to 100 meteors per hour under ideal viewing conditions. Conditions this year are good due to there being no moon visible. Let’s hope the skies stay clear.

Perseid meteors are often bright with persistent trails which can linger for a while after the meteor has burned up. Further information on the Perseid meteor shower and how to view it, can be found in this site.

While you are looking for meteors, there will be other objects to look out for such as the Planet Jupiter, the Milky Way, Summer Triangle and manmade Satellites and more.

The Twitter Meteorwatch will start at 21.30 BST on the 11th of August and will continue through to the evening of the 14th of August. Amateur and professional astronomers from the US and other countries are invited to join in and take over from the UK, when the sun comes up here, helping make the event run continuously and be truly international. The event will close in the UK, in the early hours of the 15th of August 2010.

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