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Monday's Supermoon Will Be Extra Special

PHILADELPHIA (CBS) - Monday's full moon is the second of three consecutive "supermoons" -- but this one will be super-duper.

The moon's orbit is more oval than circular, with its farthest point from the earth called "apogee" and its closest point "perigee."

When the earth's natural satellite is full at perigee, it's called a "supermoon" and Franklin Institute Chief Astronomer Derrick Pitts says this one's special:

"It happens that this year, next Monday, this will be the closest of those perigees that has happened since 1948."

Pitts says although some astronomers are saying the moon will appear 14% bigger and 30% brighter:

"It'll be almost impossible for you to tell that there's any difference in size or brightness, from this perigee to any other perigee."

But if you see the moon as it's rising close to the horizon, it will look bigger.

"That happens to be an optical illusion," says Pitts.

But no less magical to behold.

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