Blood Moon Lunar Eclipse

The moon is earth’s natural satellite that orbits around the earth. It is a non-luminous object, which simply means it cannot emit its own light. It just reflects the light from the sun, and hence we can see the moon in the first place.

A blood moon lunar eclipse wasn’t always something to look forward too. Early Mayan and Mesopotamian civilization thought it as some monster or evil eating away the moon. As a way of protesting and protecting the moon against such evil hands, they would shout and scream. Soon after the moon would turn normal , they would think that they had been successful in protecting the moon. 

Blood Moon Lunar Eclipse

Now after several centuries of scientific development we know that the moon doesn’t need any kind of protection from us.

Blood Moon Lunar Eclipse

Blood Moon Lunar Eclipse

So naturally if something were to block the light from being reflected off the moon’s surface, then in theory the moon should disappear from our sight. But this is what, that doesn’t happen.

I mean yes the earth does come between the sun and the moon during the lunar eclipse, but the moon doesn’t simply disappear away from our sight,like in  the case Blood Moon Lunar Eclipse. We can see a reddish moon .

Blood Moon Lunar Eclipse

The lunar eclipse only takes place during a full moon, which happens every 29.5 days or the time it takes the moon to complete an entire revolution around the earth. And Blood Moon Lunar Eclipse is one such day.

July 2018 Blood Moon Lunar Eclipse

So why don’t we have lunar eclipse every month?

That’s because the moons orbit is slightly tilted in relation to the earth’s, so the earth, moon and the sun don’t always perfectly align.

July 2018 Blood Moon Lunar Eclipse

When the earth comes between the sun and the moon , two kinds of shadows appear,

  1. Penumbra (larger, lighter shadow)
  2. Umbra (smaller and darker shadow)

July 2018 Blood Moon Lunar Eclipse

Depending on these shadows there are 3 types of lunar eclipse,

  1. Total Lunar Eclipse
  2. Partial Lunar Eclipse
  3. Penumbral Lunar Eclipse
  • Total Lunar Eclipse

When the sun, moon and the earth, comes in perfect alignment and the moon falls between the earth’s umbral shadow, then we get the total lunar eclipse. Due to all these factors coming into play, the total lunar eclipse is slightly rarer than the other two, but it certainly the most striking out of the rest. It is at this time the moon gets its distinctive blood red color.

Blood Moon Lunar Eclipse is a total lunar eclipse.

July 2018 Blood Moon Lunar Eclipse

  • Partial Lunar Eclipse

As the name suggest, occurs when the earth, moon and the sun doesn’t perfectly align, so only part of the moon passes into the earth’s umbra. Earth’s shadow appears very dark on the side of the moon, facing the earth.

July 2018 Blood Moon Lunar Eclipse

  • Penumbral Lunar Eclipse

Occurs when the moon passes through the earth’s penumbral shadow. The event is so subtle that is really hard to notice for normal eyes. The moon will appear just slightly dark then normal.

July 2018 Blood Moon Lunar Eclipse

Lunar eclipses can occur upto 3 times a year and can be observed across the entire night sky around the world.

Now coming back to main question

Why does the moon appear red? Or from where does the moon get its distinctive red colour?

NASA did a very interesting simulation. They simulated the , how the earth would look from the lunar surface during a total lunar eclipse, and this how it looked,

Blood Moon Lunar Eclipse

See the red ring surrounding the earth?

When do you see that kind of red hue everyday?

Yes, that’s absolutely right! Either a sun-set or a sun-rise.

As we know the earth’s atmosphere simply bends the red wavelengths of light around the planet.

So that redness you see in the NASA simulation is basically a combination of sunset and sunrise occurring on either halves (one facing the sun, and one away) of the earth.

This is caused due to the phenomenon called Rayleigh’s Scattering.

July 2018 Blood Moon Lunar Eclipse

Which is defined as the scattering of light by particles in a medium, without a change in wavelength. It accounts, for example, for the blue colour of the sky, since the blue light is scattered slightly more efficiently than red. It describes how different colours interact with the earth’s atmosphere.

July 2018 Blood Moon Lunar Eclipse

During the sunrise or sunset, the light travels through more of earth’s atmosphere before reaching the eye. And this has two consequences,

July 2018 Blood Moon Lunar Eclipse

  1. It means more overall sunlight is being scattered, making the sun appear dimmer. That is exactly why you can gaze at the setting sun, and not even look at it during the daytime.
  2. More scattering means more blue light, gets scattered away leaving the redder wavelengths behind.

Similarly the ring around the earth during the lunar eclipse is red because the sun light travels through a longer distance from end of the planet to the other.

Therefore during the total lunar eclipse the shorter blue wavelength of light are scattered more outwards by the earth’s atmosphere.

July 2018 Blood Moon Lunar Eclipse

The longer red wavelength is bent or refracted inwards towards the moon, making it appear red.

The brightness of this red glow depends on the dust and cloud present in the earths atmosphere.

A volcanic eruption can cause so much ash in the earth’s atmosphere to render the moon dark red or even black.

Is it safe to look at a lunar eclipse with naked eyes?

Unlike solar eclipse, it is completely safe to look at the lunar eclipse with naked eye.

Only because of the distances of the sun and moon from the earth that we are able to witness a total lunar eclipse.

July 2018 Blood Moon Lunar Eclipse

As the moon moves an inch away from the earth each year, one day after millions of years from nowthe moon will be too far away from us to fall completely under the umbral shadow. Until then we can occasionally enjoy our own planet’s shadow on the largest object in the night sky and our only closest companion in the cosmos, our moon!.

please comment down your views regarding the article, ‘Blood Moon Lunar Eclipse’  and do share it with your friends .

I would highly recommend a few books that would really help you to know  in depth regarding the cosmos:

  4. A Brief History of the Universe: From Ancient Babylon to the Big Bang (Brief Histories)
  5. The Physics Book: From the Big Bang to Quantum Resurrection, 250 Milestones in the History of Physics (Sterling Milestones)
  7. Cosmos
  8. Relativity: The Special and the General Theory (Routledge Classics)
  9. Black Holes: The Reith Lectures
  10. The Oxford Companion to Cosmology (Oxford Quick Reference)

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July 2018 Blood Moon Lunar Eclipse


I am Mayukh Bagchi. 4th year Undergraduate Engineering student at SRM University , physics and in general Astrophysics is my passion and I want to pursue the same. This blog is dedicated to serve the community with honest and clear insights to the cosmos.


check out the post right here · August 5, 2018 at 2:40 pm

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    Mayukh · August 5, 2018 at 3:44 pm

    Your welcome! I’m really glad

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