The spectacular Blood Moon eclipse will grace the skies over Britain on the morning of January 21. During the eclipse, the January Full Moon will completely dip into the darkest portion of the Earth’s shadow. As the Moon hits the planet’s shadow, known as the umbra, it will perfectly align with the Earth and the Sun. And when the Moon enters its phase of eclipse totality, a dazzling trick of light will paint it a red-to-orange hue.
Why does the Blood Moon turn red during a total lunar eclipse?
Tom Kerss of the Royal Observatory Greenwich told Express.co.uk the red light visible on the Moon is the result of sunlight scattering in Earth’s atmosphere.
The astronomer said: “When the Moon passes into the umbra, which is what will happen this time, we will see a total lunar eclipse and that means the Moon will be fully within the darkest part of the Earth’s shadow.
“Because the Earth’s atmosphere is made of gases which refract light and scatter light, what we see is a kind of filtering effect where light passes through the Earth’s atmosphere.
“The blue light is bounced all over the place, hence we have blue skies, and the red light passes through.
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“So behind the Earth there is actually a good deal of red light in the atmosphere and that means the Earth’s shadow is actually a really dark red colour.
“The Moon will take on this colour and this leads to what is sometimes referred to as a Blood Moon because the Moon becomes such a deep red shade when it goes through the umbral shadow.
“So we’re going to see it from the UK and it’s going to be widely visible from the United States.”
The astronomer added the entire light show will be an incredibly “amazing” spectacle to witness.
The effect of light is known as Rayleigh Scattering and is responsible for the red colour of sunsets and the colour of blue eyes – there are no blue pigments in the human eye.
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What causes a total lunar eclipse?
When the Moon spins around the Earth, it orbits the planet at a slight tilt in relation to the plane of the Sun.
As a result, the Earth sometimes appears between the Sun and the Moon.
Space agency NASA said when this happens, sunlight which normally illuminates the Moon, is obscured by the Earth.
NASA explained: “Instead of light hitting the Moon’s surface, Earth’s shadow falls on it.
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“This is an eclipse of the Moon – a lunar eclipse. A lunar eclipse can occur only when the Moon is full.
“A lunar eclipse can be seen from Earth at night. There are two types of lunar eclipses: total lunar eclipses and partial lunar eclipses.”
A total lunar eclipse occurs when the Earth is directly in-between the Sun and the Moon.
However, when the Moon is directly in-between the Earth and the Sun, we witness a solar eclipse.