Overview

Of all the astronomical phenomena that we can experience from Earth, probably the most spectacular are eclipses: that fascinating series of coincidences that result in the perfect and elegant interposition of the celestial bodies in the sky. On Tuesday, November 8, the world—or a part of it—will observe a lunar eclipse, with the Moon set to take a reddish hue as it slips into Earth’s shadow. Let’s see what is special about this event and why the Moon turns red during its eclipse.

The science and other stuff to know

The Sun is 400 times larger than the Moon, but it is also 400 times farther away from us than the natural satellite, per Britannica. Their sizes in the sky are such that they appear identical from Earth’s perspective. This could be an isolated consequence, hardly noticeable if their paths in the celestial vault never crossed.

The path that the Sun travels throughout the day through the sky—an apparent path, of course, since we are the ones who move around it—is called the ecliptic. The Moon also describes a path in the night sky that intersects the ecliptic at two points, which are known as nodes.

According to a NASA article, when the Sun and the Moon pass through a node at the same time, a total solar eclipse occurs: the Moon stands between us and the Sun, completely blocking the Sun’s disk and producing one of the most beautiful and emotional astronomical phenomena. If both stars pass through the node very close, but not at the same time, a partial solar eclipse occurs: the Moon covers a part of the solar disk.

Lunar eclipses are slightly more modest events than lavish solar eclipses, but they are no less fascinating. In this case, the stars are at opposite nodes because the Sun, fortunately, does not pass between the Earth and the Moon on its path. The Earth remains in the center of both bodies, and the Moon crosses the umbra, or cone of shadow cast by our planet, NASA explains. A total lunar eclipse occurs when the lunar disk enters the umbra zone completely, whereas a partial lunar eclipse occurs when the Moon remains in the penumbra, a half-shadow region near the umbra.

The Moon turns red during a lunar eclipse because the only sunlight reaching the Moon passes through Earth’s atmosphere. Once the Moon is in the umbra zone, the few rays of light that reach it have been scattered by planet Earth and its wavelength is longer. This illuminates the lunar disk with the dim reddish light corresponding to the type of light with the lowest energy in the spectrum. During the eclipse, the more dust or clouds in the Earth’s atmosphere, the redder the Moon will appear.

So what?

On Tuesday, November 8, the Moon will turn blood-red thanks to the last total lunar eclipse until 2025. The eclipse on Tuesday will begin at 3:02 a.m. EST (08:03 GMT) when the moon enters the outermost region of Earth’s shadow.

According to NASA, the phase of totality—when the entire lunar disk is in the umbra—will be visible from North America, Alaska, Hawaii, Ecuador, Colombia, and the western regions of Peru and Venezuela. In other areas, it will only be partially visible; that is, they will only be able to see the stage where the Moon is in the twilight zone because the Moon can be seen on the horizon before reaching totality.

You don’t need any special glasses that protect your eyes to see a lunar eclipse; however, binoculars or a telescope will improve the view and the red color. The best viewing conditions are in a dark environment away from bright lights.

What’s next?

Although we will have partial lunar eclipses—also called penumbral—in the coming months, the next total lunar eclipse will not take place until March 14, 2025. So this is an unmissable opportunity to see the Blood Moon in all its splendor and enjoy the curious series of coincidences that make such an astonishing phenomenon possible.

If you live in a region where the eclipse will not be visible or the night does not grace you with a clear sky, you can watch NASA’s live broadcast and enjoy the event in real time.