When Earth's moon is in full eclipse then a "Blood Moon" occurs. The striking feature of this Moon is that instead of white colour it becomes red or ruddy-brown. Before discussing the features of blood Moon, first we will see what is an eclipse?
What is an Eclipse?
An eclipse takes place when one heavenly body such as a Moon or planet moves into the shadow of another heavenly body. In lunar eclipse the Moon moves in an orbit around the Earth and at the same time Earth orbits the Sun. Sometimes Earth moves between the Sun and the Moon. At this time, Earth blocks the sunlight that is reflected by the Moon and shadow of Earth falls on it. This is known as an eclipse of Moon or a lunar eclipse. Also, a lunar eclipse occurs when Moon is full.
There are two types of Lunar Eclipses: a total lunar eclipse and a partial lunar eclipse. A total lunar eclipse occurs when the Moon and the Sun are on exact opposite sides of Earth. In partial lunar eclipse, only a part of the Moon enters Earth's shadow and it depends upon the position of the Sun, Earth and the Moon how they are lined up.
Do you know that our moon is made up of 20 smaller moonlets?
Now, we will see what makes Moon super?
A supermoon occurs when the full Moon coincides with the Moon's closest approach to Earth in its orbit. Supermoons make the Moon appear a little brighter and closer than normal.
Why Moon becomes red or why it is known as Blood Moon?
As we know that Moon orbits around the Earth and Earth orbits around the Sun. Moon takes around 27 days to orbit the Earth. The relative positions of the Sun, the Moon and the Earth change during the Moon's orbit.
During total lunar eclipse, Moon remains fully in Earth's shadow. And at the same time small amount of light from Earth's falls on the surface of the Moon during sunrise and sunset. Since, the light waves are stretched out, they look red and when this red light strikes the surface of the Moon, it also appears red. Or we can say that when Earth comes in between the Sun and the Moon, Moon will not receive direct sunlight from the Sun. The light which is seen is refracted through Earth’s atmosphere, giving it a red tinge. It depends upon the pollution, cloud cover in the atmosphere that how much red the Moon appears. And this colourful effect sometimes calls a lunar eclipse a Blood Moon. Do you know that roughly two or four lunar eclipses occur every year according to NASA and each one is visible over about half the Earth?
From this article we understood that a blue moon is the second full moon in a single calendar month, a supermoon is a moon that is full when it is at its closest point in its slightly elliptical orbit around the Earth and a total lunar eclipse or blood moon in which Earth's shadow upon the lunar eclipse gives it a reddish colour.