Most of the United States will be treated to a total lunar eclipse next month, with the moon’s surface taking on an eerie red hue.
According to NASA, the total eclipse will take place overnight between Thursday, March 13 and Friday, March 14, with the eclipse hitting totality in the early hours of Friday morning.
For just over one hour, the moon will take on a red or orange hue, leaving stargazers spellbound in the process.
But why will the lunar surface be red?
To answer that question, one has to remember that the sun’s light is emitted in all different colors of the rainbow in approximately equal amounts, and humans observe that light as the color white.
Each color is emitted from the sun in different wavelengths, however, and that impacts how we perceive that light when it enters our atmosphere.
Once light reaches Earth’s atmosphere, it is scattered in all different directions, according to NASA. It so happens that blue light is scattered more because it travels in shorter wavelengths, and as a result, we perceive the sky as having a blue color.
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By contrast, red and orange light travel in much longer wavelengths, allowing them to travel more directly through our atmosphere. Thus, later in the day when the sun is lower on the horizon and its light travels at a shallower angle through the atmosphere, the sky appears to be red or orange in color.
The same phenomenon occurs during a lunar eclipse. Because the moon is passing through the Earth’s shadow, most of the sun’s light is blocked from reaching its surface. The light that does make it through that shadow is light that travels in longer wavelengths, hence the red or orange color of the moon’s surface.
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The partial eclipse of the moon will begin late in the evening on March 13, with a progressively larger portion of the moon's surface covered by the Earth's shadow.
When the eclipse reaches totality at 1:26 a.m. Central time, those with a clear view of the eclipse will be able to see the reddish color of the moon's surface for approximately one hour and five minutes, as totality ends at 2:31 a.m.
The partial eclipse will then end at approximately 3:47 a.m., according to NASA.
