“The famous Perseid meteor shower occurs between July 17 and August 24, 2021, peaking on August 12 between 8:00 pm and 11:00 pm (Legal Time) with a predicted hourly rate of 110 meteors per hour, if the observation conditions are perfect.
The Perseids are the most impressive and popular meteor shower of the year, as they have a high meteor rate and occur every year in summer (in the northern hemisphere) under pleasant temperatures and starry nights. They are caused by the passage of the Earth by the fragments of comet 109P / Swift-Tuttle, which were left behind during its passage. The orbit of this comet has a period of 133 years and the last time it entered the inner solar system was in 1992. The radiant of this meteor shower, that is, the point from which the traces of its shooting stars seem to come out, is located in constellation of Perseus.
The intensity of the Perseids varies from year to year, in part due to lunar conditions. If a full moon is shining above the horizon during the night of maximum activity, the display will be reduced as most meteors are faint and moonlight will make them difficult to see. Fortunately, in 2021 the time of the New Moon phase occurs on August 8th, which will provide excellent conditions for observing the Perseid meteor shower on the night of August 12th and the early morning of August 13th.
In Portugal, the best time to observe them with the naked eye will be from 9.30 pm on the 12th of August. Before that time, in addition to the sky being still clear, the radiant is still below the horizon on the northern side of the sky. As the Earth rotates, the radiant rises in the sky. After 9:30 pm, with the radiant low on the horizon (see Fig. 1), most activity is blocked by the horizon, but the few meteors that appear in this early evening are special, as they travel a great distance in the sky, lasting longer. time. As the night progresses, the radiant continues to rise in the sky, and the meteor trails get shorter and shorter, lasting only a few tenths of a second around midnight. At the end of the night, before dawn, the radiant is even higher in the dark sky,the meteors being more visible but lasting less time.
We advise you to go to the countryside, out of the city lights, with an unobstructed horizon. If the sky appears clear, we will have a wonderful view of the sky. Jupiter will be seen in the constellation of Aquarius, Saturn at his side in the constellation of Capricorn, and the wonderful summer constellations will already appear in all their splendour.