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View Full Version : Episode 17: Where does the Moon Come From?



Fraser
2007-Jan-01, 11:25 PM
We take the Moon for granted, but its effect on the Earth is very important; possibly even critical for the formation of life. But where did it come from> Did the Earth and Moon form together? ...

Read the full blog entry (http://www.astronomycast.com/solar-system/episode-17-where-does-the-moon-come-from/)

Ted H.
2007-Jan-03, 10:16 PM
Great show, as usual. It seems every episode gives me a few questions. One of the questions that came to mind from this episode concerned tidal locking. The moon is locked to the Earth, and if I'm not mistaken, the 4 large moons of Jupiter, and Titan are also tidally locked. Why is Mercury not locked to the Sun?

Mrs B
2007-Jan-03, 10:17 PM
Hello there astronomy enthusiasts! This is my first post so bear with me...
Love the podcasts! I've stupified my collegues, friends and relatives with my inexhausitble knowledge of the universe thanks to astronomycast!!!
After listening to the Moon-podcast: I have a question about the moon and where it came from/where it is going...
I have heard an urban rumour that the Moon wil be orbiting happily around Earth for millions of years to come but will eventually be 'crushed' in some way by it's gravitational squeeze and end up as a disk aroud the earth just as much as we see Saturns rings today as 'bits of debry'. Can you put my mind at rest about this or will Earth look everything the bit as the Universal Studio logo at some time in the future? (that's propably where I got it from...). And if not, how did this theory (if you have ever heard of it) come about? I know this conflicts to what Dr Gay said about the moon slowly moving away from Earth some mm a year. But once in it's stationary position, what will happen?

In case you might wonder; Belgian winter evenings are very long and urban legends tend to be on the surreal side over here...

Keep up the good work, hope 2007 will bring all astronomers the Eureka things they've been looking for...

Kind regards, Mrs B

Fraser
2007-Jan-04, 12:53 AM
I really enjoyed doing this show. It was nice to have a more focused topic that we could deal with more fully.

chigh
2007-Jan-05, 02:56 AM
And here I thought it came from Wisconsin!

ahsanali
2007-Jan-06, 04:06 PM
Since the moon formed as a disc around the Earth coalesced as the rocks and debris in the disc were pulled together by their gravity, I do not think that simple gravity alone will be able to break it up into a disk again!

Furthermore, a sphere is an equilibrim state for something drawn together by gravity so the moon should stay the way it is. Of course if a huge impactor was to whack the moon into smithereens, we might get a disc again before it collapses into a moon again...

Just my 2c worth, correct me if I am wrong!

ahsanali
2007-Jan-06, 04:07 PM
This was one of the best shows ever, I really enjoyed it!

-Ahsan

DannyLiverpool
2007-Jan-06, 08:27 PM
i guess im smarter than i first thought...lol......

i perfered the 3rd theory about the mars size planets crashing seemed to settle well and answered my questions..

cheers guys

DaveHein
2007-Jan-08, 11:24 PM
Thanks. Great show :-) It answered all my questions and then some.

--
Dave Hein
Houston, TX

davew
2007-Jan-09, 05:21 PM
Thanks for a great show

dhd40
2007-Jan-10, 04:09 PM
i guess im smarter than i first thought...lol......

i perfered the 3rd theory about the mars size planets crashing seemed to settle well and answered my questions..

cheers guys

Has it been said where the Mars size planet went to? Did it merge with the Earth and the Moon completely, or was deflected to ... where?

darkspym7
2007-Jan-11, 08:46 PM
If the moon moved far enough away from the earth to cause us to have 1000 hour days, how would that impact the environment of the Earth, and would it be possible to sustain human life here?

Dowser
2007-Jan-12, 07:46 PM
The current theory is the moon was formed after a collision of the Earth with a Mars size body and this created a debris ring around the Earth which then condensed and became our moon.
Anyone know how these pieces of debris through gravitational forces can create a nice smooth, SOLID round object , the moon. I can take many large boulders here on Earth, smash them together and all I get is broken pieces of rock, I don’t get a nice solid body.

luckynate
2007-Jan-15, 01:50 PM
The current theory is the moon was formed after a collision of the Earth with a Mars size body and this created a debris ring around the Earth which then condensed and became our moon.
Anyone know how these pieces of debris through gravitational forces can create a nice smooth, SOLID round object , the moon. I can take many large boulders here on Earth, smash them together and all I get is broken pieces of rock, I donít get a nice solid body.
yeah but smash the rocks together after theyve been in an atomic blast or other high energy scenario like a planetary collision...the rocks would easily melt together from the intense heat. Also, dust can be compressed together to form solids under high pressures. Gravitation could account for enough pressure to form the dust and molten rock into a solid glob....
also there have been MANY impacts on the moon after it's formation, which would again melt rocks and homogenize the entire body.....

Mrs B
2007-Jan-18, 07:28 PM
Just thought about good old Voyager 2 making contact with Miranda, moon of Uranus. Maybe I'm way off again but here goes...
Miranda is that little moon that has supposed to have been smashed as much as 5 times by stuff flying through space and the debris would have stayed in the area and come together bit by bit. But Miranda is so small that it could not sustain any internal activity which could heat the small thing up again to make it less rough.
So someone very smart supposed tidal heating caused by gravitational tug from Uranus or tidal effects of a temporary orbital resonance with Umbriel could heat the moon up to smoothen some of the surface.
What kind of gravity are we talking about here that could exercise so much energy to compress gas or make icy bits smooth again?
Can this moon shed some light on ours? (...figure of speech...)

gGriffeth
2007-Feb-10, 01:54 PM
I love this show! It actually helped me w/ a few questions.