This year the Moon will make it difficult to observe the Perseids. The best time to observe them will be the early hours of Monday, August 12 to 13 , directing the gaze towards the darkest areas of the sky, in the opposite direction to the position of the Moon. The only requirements for observation are a place protected from artificial light, a cloudless sky and a little patience.
How to observe them
The Perseids are visible from the entire northern hemisphere in the middle of summer. Although its moment of maximum activity takes place on the night of August 12 to 13, the Perseids usually begin to be seen towards July 23 and end towards August 22. The speeds of these meteors can reach 200,000 kilometers per hour . Its high activity, together with the favorable atmospheric conditions for observation during the boreal summer, makes the Perseids the most popular and most easily observable meteor shower , among all those that take place throughout the year.
Due to the proximity to the full moon phase, this year is not very favorable for the observation of the Perseids. Indeed, the full moon of August will be given on the 15th, but that does not mean that the observation of the meteors has to be fruitless.
Early bird prize.- Those who dare to watch the Perseids before dawn will benefit greatly for two reasons. On the one hand, because the intensity of the rains of stars is always greater in those hours, because it is when we are on the side of the Earth that moves in the direction of the trail of fragments left by the comet. And, on the other hand, the Moon will set a few hours before dawn leaving a good time of darkness before it begins to clear.
Specifically, on the weekend of August 10 to 11 the Moon will go to bed at about 3 in the morning leaving about three hours of very dark sky before dawn, because the Sun rises now at 7h20m.
Each passing day, the gibbous Moon will be brighter and go to bed later until it reaches full moon. In the early morning of the 13th, when the maximum of meteoric activity is expected, the Moon will set at about 5 o'clock in the morning, so the dark night time will last around one hour.
For night owners.- To try to see the Perseids while the Moon is up, after dark and during the first part of the night, it is best to turn our backs completely on our satellite which, on the night of the maximum, will be in the constellation of Sagittarius.
We advise you to settle on a sunbed facing the opposite direction to the Moon, its brightness will hide the weakest persecutions, but the brightness of the most intense can overcome that of Venus and make them visible even against a background of relatively bright sky .
For all.- The local conditions of observation are decisive and it is always preferable to monitor the clearest area of clouds and the most free of light pollution. A place where there are mountains to the east, if we observe in the first part of the night (to be able to hide the Moon or part of its brightness) it will be particularly suitable.
Although its radiant is in the constellation of Perseus, it is not necessary to know the constellations, nor is it essential to look towards Perseus, to see the Perseids. Shooting stars can appear anywhere in the celestial vault. The number of observable Perseids per hour is very variable. In a very dark place and with the radiant high above the horizon it can reach one hundred, however, the number of meteors observed per hour can vary very quickly as the density of fragments in the comet's wake varies.
What are the Perseids ?: debris from a comet ...
Comets, as described by their orbits around the Sun, leave a trail of gases, dust and debris (rocky materials) in space. This trail remains in an orbit very similar to that of the parent comet.
Each comet thus forms a ring in which numerous cometary fragments are distributed. When the Earth, in its movement around the Sun, finds one of these rings, some of the rock fragments (meteoroids) are trapped by its gravitational field and fall at high speed through the atmosphere forming a meteor shower. The friction with atmospheric gases calcines and vaporizes the meteors that appear bright for a fraction of a second forming what we popularly call shooting stars.
The height at which a meteor becomes bright depends on its speed of penetration into the atmosphere and is usually around 100 kilometers. However, the high brightness and high transverse speed of some meteors cause a spectacular effect, causing the illusion in the observer that they are very close.
Meteoroids of less than a kilogram mass vaporize completely in the atmosphere, but the largest and densest (of rocky or metallic consistency) form meteorites: calcined remains that fall on the Earth's surface.
... And also tears from San Lorenzo
As every year around this time, the Earth, in its path of translation around the Sun, passes through a place populated by the rock fragments that the periodic comet 109P / Swift-Tuttle throws when it visits this area every 133 years. The corresponding meteor shower seems to have a single center of origin, a point from which all shooting stars seem to emerge. That point is called radiant and its location is used to name the rain of stars. Thus, the Perseids have their radiance in the constellation Perseus.
The Perseids also receive the name of Tears of San Lorenzo for the proximity of the maximum meteor shower to August 10, the day of the holiday of the Spanish martyr who, in the year 258, was burned on a grill in Rome.
The origin of the name of Perseidas
Drop down
In Greek mythology, the rain of Perseids is related to Zeus's visit to the mortal Dánae. An oracle had warned Acrisio, king of Argos, that he would be killed by the son of his daughter Danae. In order not to have grandchildren, Acrisio locked Danae in a bronze tower. But Zeus took the form of a shower of gold (Perseids) to visit the maiden and make her pregnant. From this peculiar union was born Perseus, who after finishing the Medusa and rescuing Andromeda, would end up fulfilling the prophecy of the oracle.
Rafael Bachiller is director of the National Astronomical Observatory (National Geographic Institute) and academic of the Royal Academy of Doctors of Spain.
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