This image of the full moon was taken by Alamelu Sundaramoorthy from Portland, Ore. on July 3, 2012.
Credit: Alamelu Sundaramoorthy
The moon shows its full face to Earth once a month. Well, sort of. In fact, when things are perfectly aligned and the moon would be 100 percent full, there is a lunar eclipse, so in reality the moon is never perfectly full. And sometimes — once in a blue moon — it is full twice in a month.
Full moons in 2015
Full moon names date back to Native Americans. Some tribes kept track of the seasons by giving distinctive names to each recurring full moon. Their names were applied to the entire month in which each occurred.
|Jan. 4||Wolf Moon||11:53 p.m.||04:53 (1/5)|
|Feb. 3||Snow Moon||6:09 p.m.||23:09|
|Mar. 5||Worm Moon||1:05 p.m.||18:05|
|Apr. 4||Pink Moon||8:05 a.m.||12:05|
|May 3||Flower Moon||11:42 p.m.||03:42 (5/4)|
|June 2||Strawberry Moon||12:19 p.m.||16:19|
|July 1||Buck Moon||10:19 p.m.||02:19 (7/2)|
|July 31||Blue Moon||6:43 p.m.||10:43|
|Aug. 29||Sturgeon Moon||2:35 p.m.||18:35|
|Sept. 27||Harvest Moon||10:50 p.m.||02:50|
|Oct. 27||Hunter's Moon||8:05 a.m.||12:05|
|Nov. 25||Beaver Moon||5:44 p.m.||22:44|
|Dec. 11||Cold Moon||6:11 a.m.||11:11|
And here's how a full moon works:
Just a phase
The moon is a sphere that travels once around Earth every 29.5 days. As it does so, it is illuminated from varying angles by the sun — what we see when we look at the moon is reflected sunlight. On average, the moon rises about 50 minutes later each day, which means sometimes it rises during daylight and other times during nighttime hours. Here’s how the phases go:
At "new moon," the moon is between Earth and the sun, so that the side of the moon facing toward us receives no direct sunlight, and is lit only by dim sunlight reflected from Earth. As it moves around Earth, the side we can see gradually becomes more illuminated by direct sunlight.
A week later, the moon is 90 degrees away from the sun in the sky and is half-illuminated from our point of view, what we call "first quarter" because it is about a quarter of the way around Earth.
A week after this, the moon is 180 degrees away from the sun, so that the sun, Earth and the moon form a line. The moon’s disk is as close as it can be to being fully illuminated by the sun, so this is called "full moon."
A week later, the moon has moved another quarter of the way around Earth, to the third quarter position. The sun's light is now shining on the other half of the visible face of the moon.
Finally, a week later, the moon is back to its new moon starting position. Because the moon’s orbit is not exactly in the same plane as Earth’s orbit around the sun, they rarely are perfectly aligned. Usually the moon passes above or below the sun from our vantage point, but occasionally it passes right in front of the sun, and we get an eclipse of the sun.
Each full moon is calculated to occur at an exact moment, which may or may not be near the time the moon rises where you are. So when a full moon rises, it’s typically doing so some hours before or after the actual time when it’s technically full, but a casual skywatcher won’t notice the difference. In fact, the moon will often look roughly the same on two consecutive nights surrounding the full moon.
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