Aquest lloc Web ha deixat d'actualitzar-se. Trobareu la nova versiķ a ServiAstro
More topic actionsEdit   Attach

Perseids 2019


Astronomical Agenda 20198

Monography about meteor showers


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? How to observe it?

ZHR (zenithal hourly rate) index gives us an idea of the amount of meteors that under ideal observation conditions can be seen per hour at the maximum of a meteor shower with the radiant at the zenith. According to the International Meteor Organization (IMO) for Perseids 2019 the ZHR will be over 110. But you have to keep in mind that by varying the observation place the radiant is placed at different height above the horizon and the visibility of the meteors changes. For the Iberian Peninsula and 2019 it is [[ 20180813_10_100] [calculated]] a much lower ZHR, around 30 meteors per hour.

The peak activity this year is expected around four o'clock in the morning (official time) on August 13.

Remmember that the shower is considered active not only on the day of the maximum but also a few days before and after (more or less between July 17 and August 24), and that althought the number of meteors is fewer in the days before and after the peakthe conditions of observation could be more favorable. This year the maximum will be very close to the day of the full moon (August 15) with a 94.2% of illumination of the Moon that will make very difficult to see the meteors. The previous days, on the other hand, the moon will be less illuminated and it will set sooner, improving the observation conditions. The phase and time of Moonset can be seen here.

To best see the Perseids meteors concentrated and leaving some good traces you should look around the radiant, from where it seems that they leave, although they can also be seen spread out in any part of the sky. The radiant of the Perseids is in the constellation of Perseus (A.R.: 03:12, D: + 57.6 °). To find it you have to face north and then look a little to the east (map). It will be already 23ē above the horizon over midnight. Although the later and the closer to dawn you will look the better.

To see the rains, no optical device is needed, they can be seen with the naked eye. You should go away from light sources.The best approach is to recline in a lawn chair or on the ground with a pillow so you are comfortably looking up.

Links where you will find areas favorable to observation with little light pollution and where you can measure the quality of your sky:

Sky map where you can see the radiant for Barcelona (Spain) at 00:00 official Time 13/08/2019 (stellarium)

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.



In the

IMO, International Meteor Organization

Sociedad de Observadores de Meteoros y Cometas de Espaņa

This site is powered by the TWiki collaboration platform Powered by Perl