Please Explain: The Moon

Friday, August 23, 2013

We can see the moon is up there in the sky most nights, but how much do we really know about it? Dr. Juliane Gross, a research scientist in the American Museum of Natural History's Department of Earth and Planetary Sciences, tells us all about the moon--how it got there, why it orbits the earth, and what a blue moon—the kind of full moon we had on Tuesday—is.

Credit: AMNH/D. Finnin
The moon model is on display in the Dorothy and Lewis B. Cullman Hall of the Universe at the Museum of Natural History.
Credit: AMNH/D. Finnin
One of four moon rocks on display at the American Museum of Natural History, collected by astronauts during the Apollo lunar missions in the 1970s.


Dr. Juliane Gross

Comments [18]

Arlo from NYC

I am correcting a few of the errors and omissions that Dr. Gross made on this program:
1) The Earth and Moon are separating slowly, on average 1.5 inches annually. A few hundred millions years from now total solar eclipses will cease because of this. Looking back to soon after the Moon's formation, it was about 10 times closer than now, appearing huge in Earth's sky (almost the width of your hand at arms length), raising huge tides on Earth, hundreds of meters high. As a consequence of this, Earth's day was four times shorter.
2) There are many upcoming space missions planned for the Moon; several will land. In fact there are two missions planned in the next few months, by China (Chang'e 3) and NASA (LADEE).
3) The Moon can actually hold onto a thick atmosphere for many millions of years, if not quite forever. This was shown by Dr, Richard Vondrak in 1974, in the journal Nature (vol. 248, p. 657).
4) The model of lunar formation by the impact of the proto-Earth and a large planetoid that Dr. Gross mentions has been severely challenged by scientists lately; perhaps it is true, perhaps not.

Aug. 27 2013 12:21 AM
Tonero Williams from Brooklyn

Great segment. Your questions, the callers, especially the kids were insightful and fun.
Dr. Gross should be a returning guest. She makes me want do further research on the subject.
Her straight forward answer to the questions were a pleasure to listen to. I stopped my cleaning
chores to give her my full attention.

Aug. 23 2013 02:13 PM
Geoff from Yonkers

Great guest, thanks.

Aug. 23 2013 02:04 PM

These children calling in with their strong curiosity makes me almost hopeful for humanity's future.

Aug. 23 2013 01:57 PM

If the moon is so hot during the day, how did the astronauts manage on it?

Aug. 23 2013 01:54 PM
John Weber from Earth

She didn't answer the poor little girl's question. Each Full Moon per month has a name. Harvest Moon being in September. Others are Hunter Moon, Sturgeon Moon, etc. It varies by region and geography obviously.

Aug. 23 2013 01:49 PM
Amy from Manhattan

The moon does have an effect on the earth's equatorial bulge...don't know if that implies anything about tectonic plates.

Aug. 23 2013 01:48 PM
Amy from Manhattan

If we didn't have a moon, not only would we have no tides, we'd have no basis for calendar months. I'm sure we'd have come up w/some other time division--maybe 3 months, for the seasons?--but there'd be no reason for it to be ~30 days.

The night sky would be uniformly dark all the time, w/no moon phases. But we'd be able to see the stars equally well every night! And w/no moon...there'd be no references to the full moon in love songs.

If the moon weren't there, there'd be no solar eclipses, which would probably have cultural repercussions. And there'd be no "nearby" place to send space missions, which would have changed our space programs & the things we could find out from the moon about the nature of the earth.

If we had 2 moons, another factor in the tides would be their relative masses.

Aug. 23 2013 01:46 PM

In answer to the 6 yr-old's question:
In traditional skylore, the Harvest Moon is the full moon closest to the autumnal equinox. For us in the Northern Hemisphere, the 2013 autumnal equinox comes on September 22. That makes the September 18-19 full moon the Northern Hemisphere’s Harvest Moon … a bit of an early one for this year. Meanwhile, in Asia, this full moon falls on the night of September 19-20.

Aug. 23 2013 01:45 PM
Martin from Sunnyside, Queens

Why doesn't the moon have an atmosphere? would it ever be possible to have breathable air on the moon? If not, why?

Aug. 23 2013 01:44 PM
The Truth from Becky

OMGoodness how adorable is Paige? and such a great question? What is a harvest moon?

Aug. 23 2013 01:41 PM
Larry from Nyack

Does the moon affect Earth's tectonic plate movements?

Does the moon's position affect volcanic activity? correspond

Aug. 23 2013 01:38 PM

I recently read a 2nd meaning of the term "Blue Moon" which I considered to be a full moon occurring twice in one calendar month, but an astrology column said the current one is a Blue Moon as it is a seasonal quarter (summer)with 4 full moons instead of just 3, with the 3rd one that gets the label Blue Moon. The first variety occurs every 2.5 years. How infrequent is the 2nd type?

Aug. 23 2013 01:33 PM
Marla from NYC

Does the moon have poles like Earth has?

Aug. 23 2013 01:32 PM
jgarbuz from Queens

Please ask your guest if she ever heard of Emmanuel Valikovsky? He was a propenent of "catastrophism" which was poohed poohed in his day, but apparently is now part and parcel of modern cosmology.

Aug. 23 2013 01:30 PM
Arlo from NYC

Why are all of the dark areas (seas) almost all one one side? (Ignore for the moment it faces us.)

Aug. 23 2013 01:26 PM
John A

Is it still only a coincidence that an eclipse can have our moon and sun both match in size? That's a pretty good coincidence.

Aug. 23 2013 01:17 PM
Brooke from Brooklyn

I am wondering why the moon sometimes looks extremely large, and other times very small. Thanks!

Aug. 23 2013 01:02 PM

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