Total lunar eclipse upon the Yucatán Peninsula on Sunday, January 20th, 2019

The first — and only — total lunar eclipse of 2019 is happening on Sunday, January 20th, and those who live in North and South America will have a front row seat to the whole bloody show. During the eclipse, the Moon will turn a creepy shade of red, which is why these events are often referred to as Blood Moons. This particular eclipse is even more special than usual, as the Moon will be a tad closer to us than it normally is.

There’s a lot going on with this event, so let’s break down this particular eclipse. Here’s how these events happen, what makes this one special, and why some people are calling this eclipse a “Super Blood Wolf Moon.” No, really.

WHAT IS A LUNAR ECLIPSE?

A lunar eclipse occurs when the Earth passes directly between the Sun and the Moon. When that happens, the Earth blocks most of the light from the Sun, and the Moon is then plunged into our planet’s shadow, also called the umbra. However, the Moon doesn’t go fully black like the Sun does during a solar eclipse. That’s because sunlight still slips past the outer edges of the Earth and hits the Moon.

A graphic of what happens during a lunar eclipse (not to scale).
 Image: NASA

But the light that does sneak past Earth is mostly reddish-orange. That’s because the sunlight has been scattered. The light creeping around the sides of our planet is passing through a lot of atmosphere, and all of the molecules in our air cause certain types of light to, well, scatter. Light will bump up into tiny particles of nitrogen and oxygen, which flings the light outward in all directions. But this effect is more pronounced for light on the blue end of the spectrum, which has much shorter wavelengths. It bumps into all these molecules more easily, while red light, with it’s much longer and more stretched-out wavelengths, can slip through.

This scattering effect is the same reason why our sky is blue during the day, and reddish-orange at sunset. When the Sun is high in the sky, blue light gets scattered the most in all directions, with a lot of it getting directed toward our eyes. But when the Sun is at a low angle on the horizon, its light has to pass through a lot more atmosphere to reach our eyes, and that filters out blue light even more. So that’s why the reds and yellows make it through.

AND YOU SAID THIS MOON IS SUPER, TOO. DOES IT HAVE POWERS?

Sorry, but our Moon is the same old Moon its been for millennia. The name just means that this is a full Moon that will be at its closest distance to Earth on its trip around our planet. See, the Moon doesn’t revolve around Earth in a perfect circle, but more of an ellipse. That means its distance from Earth changes throughout its orbit. Supermoons are when the Moon is about 225,744 miles, or 363,300 kilometers, away. That makes them appear about 14 percent bigger and 30 percent brighter than your average full Moon.

The size of a supermoon (L) compared to the Moon when it is farthest away from Earth on its orbit (R).
 Image: NASA

WHAT’S THIS I HEAR ABOUT A SUPER BLOOD WOLF MOON?

Yes, some have been referring to this event as a Super Blood Wolf Moon. But the “wolf” part of the name simply refers to the fact that this is a full Moon in January. Indigenous tribes in North America used to keep track of the seasons by observing the full Moons, according to the Farmer’s Almanac, so they would give these events names. This title supposedly refers to all the wolves that “howled in hunger outside the villages” in January, according to the Almanac.

Of course, “Super Blood Wolf Moon” is a bit of a mouthful to say, so feel free to stick with “lunar eclipse.”



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