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Photo via Fred Espenak.

You are watching: Why does the moon appear to take on a colored hue during an eclipse

Coming up…Total lunar eclipse of January 20-21, 2019

During a lunar eclipse, you’ll view the Earth’s shadow creeping throughout the moon’s face. The shadow will appear dark, favor a bite taken out of a cookie, until the shadow completely covers the moon. Then, during the breathtaking time of totality, the shadow on the moon’s face often all of sudden changes. Rather of dark, it shows up red. Why?

The factor stems native the air we breathe. During a complete lunar eclipse, the earth lies directly between the sun and also the moon, bring about the earth to cast its zero on the moon. If planet didn’t have actually an atmosphere, then, as soon as the moon was completely within Earth’s shadow, the moon would certainly would show up black, perhaps even invisible.

Thanks to Earth’s atmosphere, what in reality happens is much much more subtle and beautiful.

Earth’s setting extends around 50 mile (80 km) above Earth’s surface. During a full lunar eclipse, when the moon is submerged in Earth’s shadow, there is a one ring roughly Earth – the ring of our setting – v which the sun’s light ray pass.

Sunlight is created of a variety of frequencies. As sunlight passes with our atmosphere, the eco-friendly to violet section of the light spectrum is, essentially, filtered out. This exact same effect, through the way, is what makes our skies blue throughout the day. Meanwhile, the reddish part of the spectrum is the very least affected.

What’s more, once this reddish light first entered the atmosphere, it was bent (refracted) toward the Earth’s surface. It’s bending again as soon as it exits on the other side the Earth. This double bending sends the reddish irradiate onto the moon throughout a total lunar eclipse.

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The amazing picture montage in ~ left combines photo of Earth, taken by the Apollo astronauts, and one by the Japanese lunar probe Kaguya throughout a lunar eclipse in 2009. A person standing ~ above the moon during a full lunar eclipse would certainly witness the planet eclipsing the sun. The pink ring approximately the planet is our atmosphere aglow through the merged light of every the sunrises and also sunsets ~ above the planet. At right, the totally eclipsed moon takes on your color. Photos via JAXA (left), Jim Fakatselis. Image and also caption via AstroBob.

Depending ~ above the problems of our environment at the moment of the eclipse (dust, humidity, temperature and also so on can all make a difference), the making it through light will certainly illuminate the moon with a color that varieties from copper-colored come deep red.

In December 1992, not long after the eruption of mount Pinatubo in the Philippines, there to be so much dust in Earth’s environment that the completely eclipsed moon can barely be seen.

Can anyone recognize in advancement how red the moon will appear during a full lunar eclipse? no precisely. Prior to an eclipse takes place, you’ll frequently hear human being speculating about it. That suspicion is component of the fun of eclipses, for this reason enjoy! and also watch because that the red moon throughout a lunar eclipse.

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A lunar eclipse takes location when the sun, Earth and moon line up in space. The moon passes v Earth’s shadow. Photo via Wikimedia Commons.

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Bottom line: The moon deserve to look red during a full lunar eclipse due to the fact that of sunshine that’s filtered and refracted by Earth’s atmosphere.

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