Lunar specialists say it will be a blue moon, or the second full moon of the month. But at the same time, they say, it will also be a red moon. It will give us a lunar eclipse. And if that were not enough, it will also be a supermoon.
And to make those events geometrically and astronomically possible, it will also be a full moon.
By now, many of us are familiar with each of those celestial ornaments and descriptions. But seldom do we have a chance to experience them all together.
A blue moon is essentially metaphorical, not some visual characteristic. But calling Wednesday's full moon a red moon recognizes that the moon is, indeed, expected to be tinged with red.
In a lunar eclipse, rays of red light pass through the Earth's atmosphere to reach the surface of the moon. On Wednesday, specialists say, those in the Washington, D.C., area will be able to see a partial lunar eclipse starting at 5:51 a.m. and continuing until the moon sets in the west about 7:15 a.m.
We have come to apply the term supermoon to one that is full but that looks bigger and brighter than the normal full moon, which occurs about once a month.
It looks bigger and brighter because it happens to be full at just about the time it makes its closest approach on a given monthly orbit.
Essentially, as it travels around the Earth each month, the moon reaches points where its distance from the Earth is the greatest and where its distance is the least.
This characterizes an orbit that is not a circle, which would always keep it at the same distance from Earth. Instead, the moon traces out a geometric figure known as an ellipse.
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