On the night of this Friday, July 27, the longest total lunar eclipse of the 21st century will take place. The phenomenon will last for almost four hours, of which one hour and almost 43 minutes will be in full phase, that is, our satellite will be completely dark.
However, it will not disappear completely but, illuminated by sunlight passing through the Earth's atmosphere, it will be tinted red. Blood moon, they call it. To add a touch of brightness to the spectacle, Mars, which is approaching our planet in its orbit, will appear next to our satellite with a luminosity such as it has not shown in recent years.
The atmosphere will be in charge of making up the moon. From start to finish, the moon will appear red from two physical phenomena:refraction and dispersion. Refraction will take place when sunlight meets an obstacle, the Earth.
As a consequence, its rays will be deflected and only some will leak into the atmosphere. At this point, dispersal will kick in. The atmosphere will divide the white light from the sun into the seven colors of the rainbow, only the red color will get through it and color the moon. The intensity of this red will give the show its final touch.
The broadcast will begin on July 27