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Perseids 2018

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Astronomical Agenda 2018

Monography about meteor showers

Introduction

Nowadays the Perseids are, with no doubt, the most famous meteor shower among the population. There are powerful reasons which explain it clearly: on the one hand, they visit us every year in the very middle of August, when many people are enjoying their summer holiday far from big cities. It is then a perfect moment to observe this kind of sights: relaxation, time flexibility and nice temperatures to practice night activities outdoor influlence us to do it.

The Perseids are given this name because they appear to radiate from the area of the sky occupied by Perseus; that is to say, their radiant is located there. The radiant is the point of intersection with the celestial sphere and the projections of the trajectories of the meteors.

It is necessary to remember that a meteor shower consists of lots of meteoroids falling from the space into Earth's atmosphere. Meteoroids can be just like little dust specks or, the other way round, enormous rocky fragments. Terrestrial atmosphere are continuously receiving objects of this type, but concrete dates exist when the rate of arrival grows considerably and then it is said a meteor shower to occur. Meteoroids, when arrive to the atmosphere and move through it, are suddenly heated by friction and burn up giving rise to the amazing characteristic trails.

Most of the meteor showers have their origin in comets. These objects are made of ice and dust (that is why they are often called dirty snowballs) and when they arrive near the Sun, their iced parts partially evaporates and dust is thrown out and can remain trapped in the orbit of the comet. Usually, the distribution of the dust along the orbit is not uniform. The comet which generates the Perseids is Swift-Tuttle and has a period of 130 years. When this comet pass near the Sun, releases part of its matter and considerably fills that stretch of the orbit with particles.

Every year, over 11th-12th August, the Earth intercepts Swift-Tuttle's orbit and fragments one day thrown out to the space by the comet fall down through the atmosphere and a meteor shower occurs. If this interception takes place a short time after the comet has passed by (once every 130 years) the meteor shower is very intense. That is what we commonly call a "storm", when observing some thousands of shooting stars per hour is possible.

In 1992, Swift-Tuttle last visited the inner parts of the Solar System and, as a result, during the nineties remarkable Perseids events occurred. The date the Perseids appear in the sky, in the very middle of the summer, invites people from northern hemisphere to follow their evolutions.

How the shower is going to be?

The zenithal hourly rate (ZHR) gives us an idea of the amount of meteors that on ideal conditions and with the radiant placed at the zenith can be seen observing at the maximum hour, the Perseids ZHR for this year 2018 is 100. But everyplace has its own rate depending on where it has placed the radiant.

The peak activity this year is expected between 1 and 2 a.m. UT on August 12. The only 2 days old young moon will not interfere in the observation.

How to observe?

Meteors can be seen with the naked eye. The Perseids radiant is in the constellation Perseus, so it will be better to look to the north but you will be able to find meteors anywhere in the sky (see the map).

Find a place with a clear view of the entire sky. Dark areas well away from any city lights are best. Avoid places where vehicle headlights will momentarily dazzle you. The best approach is to recline in a lawn chair or on the ground with a pillow so you are comfortably looking up.

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Sky map where you can see the radiant for Barcelona (Spain) at 00:44 ( UT) on the 13/08/2018

Send images

If you want you can send your Perseids images and we will post them on this web so that everybody can contemplate them. Send the photos with their technical characteristics, your name and the place, date and hour.

Links

In the sky.org

meteorshowers.org

IMO, International Meteor Organization

http://meteorshowersonline.com/

Sociedad de Observadores de Meteoros y Cometas de Espaņa

 
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