ROBERT SIEGEL, HOST:
Tonight the moon will be at its closest to Earth in nearly 70 years. It's called the supermoon, and it will appear a little bigger and brighter than usual. The last time the moon was this close was in 1948, the same year, we should mention, that there was a surprise victory in a presidential election - President Harry Truman and New York Governor Thomas Dewey.
Well, Sarah Noble joins us now to talk about this supermoon. She's a lunar scientist at NASA. Welcome to the program.
SARAH NOBLE: Thanks.
SIEGEL: And as I've said, the moon will seem bigger and brighter but by how much? Is it really that super?
NOBLE: It is. It's about 15 percent bigger a supermoon than when it is at its first point from the Earth, and it's about 30 percent brighter.
SIEGEL: And how close will it actually be?
NOBLE: Not that much closer than usual. It's only a difference of, you know, a few hundred miles or so between this and a typical moon. The orbit of the moon around the Earth is a little bit elliptical, and so it's - the distance between the Earth and moon is sort of constantly changing. And at this point, we have a sort of special point where it's just a little bit closer than usual.
SIEGEL: Do you use the term supermoon? Is it actually an astronomer's term of art?
NOBLE: It is actually a term that comes from astrology, not astronomy. And it's something that has just recently sort of come into the vernacular. It's not really something scientists would refer to it as. Scientists would call this a perigee full moon because perigee is the point at which the Earth is closest to the moon.
SIEGEL: It's the opposite of the apogee of the...
NOBLE: Correct.
SIEGEL: ...Of the moon. What's the best way to see the supermoon tonight?
NOBLE: Just go outside. It's really simple. Go outside and look up.
SIEGEL: (Laughter) Well, when? When do we get the best view of it?
NOBLE: (Laughter) You know, any time this evening after dusk as the moon starts to rise. You know, it always looks best and biggest when it's near the horizon just because it's an optical illusion of our eyes. It will look bigger then. But it will be beautiful all evening long.
SIEGEL: Can we see with the naked eye? Can we see things on the surface of the moon that wouldn't be as evident on even a clear night when the moon is a good deal farther away?
NOBLE: I don't know that you'll see a huge difference. It will be - I mean it is bigger and brighter. It is easier to see things. You know, get out a pair of binoculars. You can certainly see a lot. But it's - again, it's not that much bigger than any other night.
(CROSSTALK)
SIEGEL: Throwing such cold water on the moon. We wanted to get...
NOBLE: (Laughter).
SIEGEL: We wanted to find some enthusiasm with the lunar scientist from NASA.
NOBLE: (Laughter) Oh, I have a lot of enthusiasm. I think the moon is beautiful every night of the month.
SIEGEL: I see. Every moon is a supermoon as far as you're concerned.
NOBLE: That's right (laughter).
SIEGEL: And as a lunar scientist talking about a phenomenon with roots in astrology - or the name, at least - can you tell us whether the supermoon has any known effect on presidential polling that would have happened in 1948 and this year?
NOBLE: (Laughter) No comment on that one.
SIEGEL: Sarah Noble, thank you very much for talking with us today.
NOBLE: Thank you for having me.
SIEGEL: That's Sarah Noble, lunar scientist at NASA, talking about the supermoon. And by the way, if you can't catch it tonight, you'll have another chance to see the moon this close to Earth in 2034 - not a presidential election year I might add. Transcript provided by NPR, Copyright NPR.