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Black Supermoon: What (Not) To Look For Wednesday Night

(CBS SF) -- A supermoon is ready to take center stage in the night sky this Wednesday, but with a rare twist: it'll be a new moon.

During this time, the moon is at the closest to the Earth than at any other time making it appear 14 percent bigger and 30 percent brighter than other full moons.

Scientists call this phenomenon a "perigee moon." The moon is usually about 238,000 miles from our planet, but because of the elliptical shape of the moon's orbit, the distance varies throughout the year. At perigee, the moon is about 12,000 miles closer to the Earth.

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The moon's phase and date of its approach to its perigee is not synced, but sometimes it's possible for a full moon to occur at the same time. This is what's known as a supermoon.

You won't be able to see Wednesday's unique supermoon due to the sun's glaring rays concealing it during day hours. But with minimal light pollution from the moon, it'll be a prime time to dig out those astronomical binoculars and go searching for faint objects in the galaxy.

As Universe Today puts it, a black moon is the simply a new moon version of a blue moon -- which is an extra full more in a season having nothing to do with color -- and is either:

  1. A month missing a Full or New Moon… this can only occur in February, as the lunar synodic period from like phase to phase is 29.5 days long. This last occurred in 2014 and will next occur in 2018.
  2. The second New Moon in a month with two. This can happen in any calendar month except February.
  3. And now for the most convoluted definition: the third New Moon in an astronomical season with four.

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The black moon could also intensify ocean waters to create surging tides, known as a perigean spring tide. In some counties, like the United States, the phenomenon is known as the King Tide. As a result, a coastal flood alert is in effect for the Bay Area until Thursday.

The black supermoon won't be back until Oct. 30th 2016, however a spectacular blue moon is expected on July 31 this year.


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