The meteor shower of the Perseids, which happens every year around the 12 of August, will have its peak of activity from 2200 hours deeste Sunday 12 until 10.00 am Monday, 13 (official hours of the Peninsula). According to the National Astronomical Observatory (NAO), this 2018 will be a year of “excellent” to be able to appreciate this phenomenon because there will be a new Moon on the 11th of August.
The Perseids -also known as “tears of San Lorenzo” because of the proximity of its maximum the 10th of August, feast day of the martyr Spanish of the same name, are visible from throughout the northern hemisphere in full summer. Therefore, they can be seen perfectly from Spain.
The velocities of these meteors can exceed 50 kilometers per second and its rate of activity can reach up to 200 meteors per hour. Although their time of peak activity usually takes place on the evenings of the 11th to the 13th of August, the Perseids usually begin to be seen towards the 17 of July and end to the 24 of August.
However, the number of meteors observable per hour is very variable. In a place dark and with the radiant high above the horizon can exceed the hundred. However, the number of meteors observed per hour can vary very quickly according to varies the density of fragments in the wake of the comet.
Thus, its high activity, along with atmospheric conditions favorable for observation during the boreal summer, the Perseids meteor shower most popular, and most easily observable, which take place throughout the year.
Why they happen the meteor showers
Comets, as they describe their orbits around the Sun, they throw to the space a trail of gas, dust, and debris (rock materials) that remains in an orbit very similar to that of the parent comet.
Each kite being formed as a ring in which are distributed numerous fragments of comments. When the Earth, in its movement around the Sun, one of these rings, some of the fragments of rock (meteoroids) are caught by its gravitational field and fall at great speed through the atmosphere forming a shower of meteors.
The friction with the atmospheric gases ashed and vaporised the meteors that appear brighter for a fraction of a second, forming what is popularly referred to as shooting stars. This is not a star but a particle of dust incandescent.
The height at which the meteor becomes bright depends on the speed of penetration into the atmosphere, but it tends to be around 100 kilometers. However, the high brightness and the large transverse velocity of some meteors cause a spectacular effect, causing the illusion in the observer that are nearby. Meteoroids of mass less than the kilogram is ashed completely in the atmosphere, but the larger and more dense (consistency of rock or metal), to form meteorites: charred remains falling on the ground.
Each year in early August the Earth crosses the orbit of comet 109P/Swift-Tuttle, which has a period of 133 years and passed close to the Sun for the last time in 1992. This orbit is filled with small particles, like grains of sand or smaller that have been released by the comet on its previous steps. When one of these particles, which were in their day the tail of the comet, enters the earth’s atmosphere at high speed, the friction heats it up vaporizarla to a great height.
How to view the Perseids
The corresponding meteor shower seems to have a single center of origin, a point that seem to arise all the shooting stars. That point is called ‘radiant’ and their location is used to name the rain of stars. Thus the Perseids have their radiant in the constellation Perseus.
To be able to see this popular ‘rain of stars’, simply any place as long as you provide a dark sky. The NAO recalls that it is preferable to observe from a location that has few obstructions to the view (such as buildings, trees or mountains), and do not use optical instruments that limit the field of vision.
Although the Perseids seem to come from the constellation Perseus can be seen in any part of the sky. The NAO recommended that you direct the eye towards the darker areas, in the direction opposite to the position of the Moon if the observation is carried out before his demise, although it indicates that what is more comfortable is to lie down and wait until the eyes grow accustomed to the darkness.