A Rare "Black Moon" Appears Tonight for North American Stargazers

Friday, 30 September 2016 - 1:10PM
Space
Astronomy
Moon
Friday, 30 September 2016 - 1:10PM
A Rare "Black Moon" Appears Tonight for North American Stargazers
Tonight, September 30th, North American skywatchers might see something strange: a patch of sky with no stars, caused by a rare "black moon." For those of you unfamiliar with the term, a black moon is essentially the evil twin of the blue moon: once every couple years, one month will have two full moons, with the second one called a "blue moon." 'Once in a blue moon' has become a byword for a rare occurrence, but black moons are also rare, occurring only once every 32 months. Actually, most people (besides hardcore Neon Genesis Evangelion fans) are probably unfamiliar with black moons, so let's break it down.

A black moon is like a regular new moon happening twice in one month (normally, each month has one full moon, one new moon, etc). A new moon occurs when the moon's Earth-facing side is completely bathed in shadow, making it invisible in the night sky. This causes a phenomenon called "lunar occultation," where the darkened moon blocks out certain celestial objects, like stars, planets, or nebulae. Tonight's occultations may be difficult to catch, since people on different parts of the Earth will have different parts of the sky obscured by the black moon. But the complete lack of a moon in the sky creates another opportunity: because the moon's light is so bright during the night, it can make other celestial objects, like stars or planets, hard to see. Here's the advice Space.com has for stargazers:

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If an occultation isn't happening in your area at a particular time, of course there are plenty of other things observers can look at, he said. Get as far away from light pollution as possible, and use a pair of binoculars or a telescope and look for galaxies or nebulas. In late September, the northern hemisphere is still facing the brightest part of the Milky Way galaxy, providing a wealth of objects for people to look at.
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For more moon fun, Randall Munroe over at XKCD has created a (semi-helpful) guide to viewing the moon's phases in art. If you want a sad song about the moon, iO Perry has this one. And if you got here looking for more info on the new film project Duncan Jones is doing to follow up his sci-fi film "Moon," we've got you covered.
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