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Each year around this time, stargazers anxiously await nature's finest fireworks show - the Perseid meteors. The 'fireball' champions of all annual meteor showers have already been streaming through our skies at the rate of about a dozen an hour, for the last few weeks. However, things will really heat up from early August 11th to the 13th, when between ninety to a hundred meteors will come zooming across the skies, making them easy to spot, even with the naked eye.
Called Perseids because they seem to spurt from the constellation Perseus, the meteors that hit our atmosphere at speeds of 140,000 mph are debris left behind by the comet, Swift-Tuttle as it travels through the area on its 132-135-year orbit. They are encountered every August when the Earth passes through the cloud of dust that lies in the path of its orbit around the sun. While the meteors are somewhat visible from the Southern Hemisphere, it is the residents of the Northern Hemisphere that get to enjoy the clearest view.
The Perseids stand out amongst the 64 other meteor showers that can be seen from earth each year because of their reliability and the number of fireballs - meteors as bright or even brighter than Jupiter and Venus - that it sends hurtling towards Earth. NASA scientists believe that these are caused by Swift Tuttle's large (26 km diameter) nucleus that produces numerous meteoroids, many of which are large enough to create fireballs.
However this year, their beauty may be overshadowed by the bright full moon - and not just any full moon but a 'super' supermoon - the largest of the three we will encounter this year. That's because while supermoons or as scientists call them 'perigee moons', can occur when the moon is full within 24 hours of its closest encounter with Earth, on August 10th, it will reach its full official phase within 26 minutes after perigee, making it appear even bigger.
Supermoons not only appear 14% larger but also as much as 30% brighter than normal full moons, if not masked by clouds and haze. While the enlarged size especially when the moon is hanging low may appear ominous, it is just the result of its elliptical orbit around the earth - when the moon is on the 'perigee' side it is about 50,000 km closer than when it is on the other end - the 'apogee' side.
NASA scientists say it is hard to distinguish between a supermoon and an ordinary full moon when it is hanging high overhead. They are usually most noticeable when the moon is close to the skyline because they appear unusually large. While nobody knows the reason for sure, Geoff Chester, an astronomer and public affairs officer at the U.S. Naval Observatory in Washington, D.C., theorizes that the enlarged size is an illusion caused by the angle at which the moon's light is coming through Earth's atmosphere.
With one occurring at least every 14 months, supermoons are pretty standard. This year's excitement is caused by the fact that there are three occasions to view the beautiful sight - July 12th, August 10th, and September 9th. In case you missed the first one, be sure to mark your calendars for the next two. Also, don't forget to make a wish if you are fortunate enough to see a Perseids meteor zip by, amidst the bright skies - It is bound to come true.
Resources: science.nasa.gov, yorkdispatch.com,theglobeandmail.com