Starship Asterisk*

Guest wrote:
I would think the far side is also more marked gets bartered [sic] with more stuff from space.

APOD Robot wrote:In fact this sharp picture, a mosaic from the Lunar Reconnaissance Orbiter's wide angle camera, is centered on the lunar farside.

neufer wrote:

Guest wrote:
I would think the far side is also more marked gets bartered [sic] with more stuff from space.

The Earth only fills up only 0.015% of the Moon's near side sky
...hence it physically blocks only 0.015% of the near side 'stuff from space.'

Chris Peterson wrote:

APOD Robot wrote:In fact this sharp picture, a mosaic from the Lunar Reconnaissance Orbiter's wide angle camera, is centered on the lunar farside.

I think the term "mosaic" is used pretty loosely here. What's been done is that a great many images made from a low lunar orbit have been mapped onto a mathematical model of the lunar surface (this is also what Google does when you look at their satellite images of Earth), and then an orthographic projection has been synthesized and rendered, showing the Moon as it would appear to an observer infinitely far away from it, thus allowing an entire hemisphere to be seen (something which is not possible in any direct image).

Guest wrote:

neufer wrote:The Earth only fills up only 0.015% of the Moon's near side sky
...hence it physically blocks only 0.015% of the near side 'stuff from space.'

I would have thought that the depth of Earths gravity well would be a big factor in protecting the near face of the Moon. Anything coming from space would be pulled in and hit us saving the completion of the man in the moon.

I don't understand this 'double crust thickness' theory tho. A body old enough to become tidally locked, should be well formed by that time, and the structure (including the crust) should be reasonably consistent.

Chris Peterson wrote:

Guest wrote:

neufer wrote:The Earth only fills up only 0.015% of the Moon's near side sky
...hence it physically blocks only 0.015% of the near side 'stuff from space.'

I would have thought that the depth of Earths gravity well would be a big factor in protecting the near face of the Moon. Anything coming from space would be pulled in and hit us saving the completion of the man in the moon.

The Earth doesn't cause a very large deviation in most of the (solar orbiting) material that passes near it. And to the extent it does, it's almost as likely to deviate a body in such a way that it misses the Moon as to hit it.

I don't understand this 'double crust thickness' theory tho. A body old enough to become tidally locked, should be well formed by that time, and the structure (including the crust) should be reasonably consistent.

Bodies don't get more uniform as they get older. In fact, they're probably at their most uniform when they're created. Then they begin differentiating, and many things can occur that result in asymmetries of density.

Guest wrote:

Chris Peterson wrote:Bodies don't get more uniform as they get older. In fact, they're probably at their most uniform when they're created. Then they begin differentiating, and many things can occur that result in asymmetries of density.

So as I understand your explanation, the moon remained molten until it after it became tidally locked to the Earth and the molten material then differentiated? Or did solid rock move thru other solid rock to change the structure of the moons crust? I'm not sure there is a third alternative.

Chris Peterson wrote:

Guest wrote:

Chris Peterson wrote:Bodies don't get more uniform as they get older. In fact, they're probably at their most uniform when they're created. Then they begin differentiating, and many things can occur that result in asymmetries of density.

So as I understand your explanation, the moon remained molten until it after it became tidally locked to the Earth and the molten material then differentiated? Or did solid rock move thru other solid rock to change the structure of the moons crust? I'm not sure there is a third alternative.

What do you mean by "molten". The deep interior of the Moon remains liquid. It's been cooling for more than four billion years. Differentiation started immediately, and the primary differentiation of iron towards the center would have occurred over a short time- not more than a few million years. Crust would have formed quickly, and over time got thicker. Density variation in the crust are part of what led to the Moon's tidal lock with Earth.

Chiming In wrote:

Chris Peterson wrote:
Density variation in the crust are part of what led to the Moon's tidal lock with Earth.

So wouldn't that mean that the heavier, more dense crust
would be on the Earth side, instead of the other way around?

Chris Peterson wrote: What do you mean by "molten". The deep interior of the Moon remains liquid.

Catalina wrote:
What causes a body/moon to become tidally locked?

Catalina wrote:
What affect of an elliptical orbit, such as our moon's, have on it being tidally locked?

Catalina wrote:
Are the moons around the other planets of the solar system all locked in such a way, as well?

Parent Body 	Tidally-locked Satellites
---------------------------------------------------------
Earth 	        Moon

Mars            Phobos · Deimos

Jupiter 	     Metis · Adrastea · Amalthea · Thebe · Io · Europa · Ganymede · Callisto

Saturn 	      Pan · Atlas · Prometheus · Pandora · Epimetheus · Janus · Mimas 
                Enceladus · Telesto · Tethys · Calypso · Dione · Rhea · Titan · Iapetus
                              
Uranus 	      Miranda · Ariel · Umbriel · Titania · Oberon

Neptune 	     Proteus · Triton

Pluto 	       Charon 

life wrote:Yesterday there was something unexpected, or the day before, and a bunch of people addressed it. seems like odd things ought to get mention. in today's lunar picture there is also an oddity which it seems ought to have been mentioned - the rather dark area toward the upper left.

Ann wrote:

life wrote:
Yesterday there was something unexpected, or the day before, and a bunch of people addressed it. seems like odd things ought to get mention. in today's lunar picture there is also an oddity which it seems ought to have been mentioned - the rather dark area toward the upper left.

I mentioned it. It is a mare,

• When the moon hits your eye like a big pizza pie
  That's a mare,

Sam Brewster wrote:Given how battered the moon, might we infer that planet earth has received that many more hits in its 5 billion years? And given the wealth of these moon hits, what might be the best estimate of measurable frequency for both locations....once per century? More? Less?