The full moon, which is repeated every 29 and a half days, occurs at times when our satellite is opposite to the Sun, and therefore illuminated completely seen from our perspective.
As the Moon's orbit is deviated about 5 degrees from the ecliptic, not every full moon happens to be submerged in the shadow of the Earth. The exact alignment, that is to say the total eclipse of Luna, only occurs on average once a year.
The full Moon next Friday July 27 will present the longest lunar eclipse of the entire 21st century. The total phase of the eclipse, when the Moon is totally immersed in the Earth's shadow, will last 1 hour and 43 minutes.
In large part, this is because the Moon will be near apogee, the closest point to Earth from its orbit, at the time of the eclipse.
The partial phase that precedes and follows the whole can be seen approximately one hour before and after. From the European countries, the eclipse will have already begun when the Moon appears on the horizon, and from a good part of the Iberian Peninsula the total eclipse will be just starting at the moment of the Moon's departure from the horizon, a moment that promises to be spectacular.
To observe this phenomenon we do not need a telescope or any other optical instrument. It is enough to look for a place with good visibility on the east horizon to be able to see the exit of the Moon.
The first contact of the lunar disk with the umbra, the darkest part of the earth's shadow, will take place at 8:24 p.m. (local time on the peninsula) and the totality will begin at 9:30 p.m., with the moon already fully inserted in the shadow. From a good part of the east of the Iberian peninsula, this will be more or less at the time of the sunset and the departure of the Moon. At 23: 13h the light will begin to strike again on the lunar disc, which will be completely illuminated again, like any night of the full moon, already at dawn.
Something curious about the total eclipses of moom is that the satellite is not completely obscured at the moment of being hidden in the shadow of the Earth. This is because part of the Sun's light is refracted in the Earth's atmosphere, projecting over the shadow zone where the Moon is located. As sunlight filters into the atmosphere, the moon's dim illumination at the time of totalization is orange or reddish. This is because the blue light is dispersed in our atmosphere, and it is the same reason why our sky is blue and the sunsets are orange.
