A total lunar eclipse, which is going to be the longest one this century, will take place on July 27 and 28 and it will also feature a visible "Blood Moon". The Moon appears red on this night because of sunlight scattering through the planet's atmosphere.

The event itself will last nearly 4 hours, with official estimates saying the eclipse alone will go on for about 1 hour and 43 minutes, according to a report by the Inquisitr. The previous Blood Moon that took place this year in January lasted for about 45 minutes. From start to finish, "the Moon takes nearly four hours to cross the Earth's dark umbral shadow," says astronomer Bruce McClure of EarthSky.org.

The eclipse will reach its peak sometime around 8:22 p.m. UTC or 1:52 AM IST. The event will be directly visible in most parts of Europe and its surrounding regions, so those in other parts of the world might have to simply enjoy the extremely rare celestial event through live news coverage or watch it online.

Blood Moon
A woman jogs on a beach with the moon in the background in Santa Monica, CaliforniaReuters

A lunar eclipse is the opposite of a solar eclipse where the Earth's shadow is cast on the Moon. When this happens, the Moon will not completely disappear from view under the shadow, it does however, take on a deep red, almost burnt orange colour. This is due to what the report points out as Rayleigh scattering—a phenomenon where light scatters through a medium, in this case the atmosphere, but without any changes in wavelength. The atmosphere filters out green and violet light and shows the Moon in a deep red, hence "Blood Moon". This is actually similar to the effect that shows sunset and sunrise in yellow and red.

As to the numerous conspiracies and old wives' tales surrounding the blood Moon, people can be rest assured that nothing out of the ordinary is actually going to happen solely because of this event. It is an eclipse and the Moon is only going to look red from certain points on the planet, not actually going to turn red and summon ancient beasts or rogue planets to destroy Earth.

Super Blood Moon
Artist's enhancement of a full eclipsed Moon.NASA