Why in 2016 Perseids will be more than usual – BBC

The Perseids – this is probably the most famous meteor shower in the Northern Hemisphere. There are several reasons. This convenient observation, because of the maximum activity of these meteors reach the middle of August, when the darkness sets in already relatively early, but the nights are still warm and comfortable for late walks outdoors. At the same time, the Perseids – a rather stable meteor shower that is in the number of meteors falling rarely falls below 60 per hour during peak activity. For comparison, another relatively stable flow Lyrids number of meteors per hour rarely exceeds 18, but, for example, Orionids produce about 25 meteors. Perhaps that is why we remember it is about the August Shooting Stars when it comes to meteors

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Normally a meteor shower is named for the constellation in which it is radiant. Due to the effect of perspective, the trajectory of cosmic particles moving at nearly parallel paths towards the observer on Earth will cross a small area of ​​the sky. . This area, the apparent source of meteors, called the radiant

For example, Leonid radiant is in the constellation Leo, and the Perseids – the Perseus.

However, sometimes called by the nearest stream to the radiant star.

Perseid stream has been known for about 2 thousand. Years. It was first mentioned in the Chinese annals dating from the year 36 AD. “More than a hundred meteors flared in the morning”, – wrote the ancient observer. Also on the Perseids it said in Japanese and Korean sources VIII-XI centuries, and in Europe, this meteor shower is called the “tears of St. Lawrence”, since the feast of St. Lawrence, which takes place in Italy, falls in the most active period of the meteor shower. However, the official discoverer of the annual August stargazing is considered a Belgian mathematician, astronomer and meteorologist Adolphe Quetelet, reported their observations in 1835.

The first researcher who calculated the average number of meteors per hour, was Edward Hayes. For a long time meteor activity it was not very high and fluctuated between 40-90 meteors in Sanchez, but after the 1858 Perseids intensified. For example, in 1863 it recorded 215 meteors per hour. At the same time was found and the reason for this gain. In mid-July 1862 American scientists Lewis Swift and Horace Tuttle opened a beautiful new comet, which was named Comet Swift – Tuttle. All the rest of the summer, it was clearly visible in the Northern Hemisphere. Maximum brightness comet reached in the last week of August. But when viewed through a telescope she had noticeable unusual structure – glowing hazy streams, diverging from the dense nucleus of the comet, like the petals of a flower

Comet 109R / Swift -. Tuttle was recognized as one of the ten most beautiful comets XIX century

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In in 1867 the famous Italian astronomer Giovanni Schiaparelli (by the way, the one who discovered the Martian canal) announced that the orbit of the newly discovered comet is almost identical with the calculated orbit for a few Perseid meteoroids. So the idea that meteor showers are associated with certain comets. This increase in activity and explain the August meteors in the 60-ies of the XIX century. The fact that due to exposure to solar radiation in the orbit of comet perihelia intensively lose stuff. Calculations show that the smaller the size of the comet particles, the easier it is to overcome the attraction and begin your journey through the solar system. However, the release rate of cometary material is much smaller than the speed of the parent comet. It is not enough to discarded dust particles scattered in different directions. As a result, they form a thick plume of particles, sometimes hundreds of thousands or even millions of kilometers across. When the Earth crosses this trail, in the upper atmosphere meteors flash – burn up in the atmosphere, particles of cometary material. The flash occurs at an altitude of around 100 km, so that each meteor seen from the surface of the planet on a large area

Comet Swift -. Tuttle makes one revolution around the sun in about 133 years. It has a fairly large core diameter of 26 km. Recall that the famous comet 67P / Churyumov – Gerasimenko, near which now works the Rosetta space probe, has a much smaller kernel – only 4 km across. The next time after the discovery of the comet Swift – Tuttle returned in 1992. Therefore, in 1990 Perseids were highly active. Within an hour in Earth’s sky flashed hundreds of meteors, and it was a lot of very bright shooting stars.

With the removal of the comet on the outskirts of the solar system activity Perseid gradually decreased until it entered the usual channel – about 60 meteors per hour

in this case, the flow is one of the most stable and beautiful, but the former abundance of shooting stars that many remember from my childhood, no longer exists.. Especially when trying to observe close to major urban centers, where the night sky is never dark enough

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But the Perseids can still surprise. In normal years, the meteor shower as it is outside the Earth’s orbit at a distance. But periodically under the influence of gravity of the giant planets, this distance may vary. In 2016, close to the Earth will be a flow station, angered by the gravitational influence of Jupiter and shifted closer to the Earth’s orbit. According to the forecast of International Meteor Organization (IMO) , the number of meteors will reach 150 per hour! Not stellar rain, of course, but much more than in previous years. Moreover, the Earth will take place at a very short distance from the two plumes of particles ejected a comet at the time flown in 1479 and 1862′s.

The particles of both loops on the night of August 12 likely , will overlap each other, which also raises several flow activity in general.

The maximum activity of the meteor shower occurs on the night of August 13th. But to start monitoring, you can now. According to the IMO , the Perseids are increasingly part of the earth’s atmosphere. It is best to observe the night of 12 and 13 August. The observations of meteors – it is a rare event in astronomy, when we do not need any additional equipment. Binoculars and spotting scopes to limit the field of view, and in fact will only interfere. It is only necessary to choose a place for observation, located away from bright light sources and gives a great view of the sky is enough. It may be in the field, on a hill on the edge of a large forest or on the lake. In the context of the city, you can go to the park or vacant lot. And when using the camera on a tripod, you can get beautiful pictures of a starry sky with a lot of meteors.