What if the Moon could sustain life?


Here is an awesome idea that I would like to see worked out. What if Luna had nearly the same composition of the Earth? Some fluke in the Big Bang provided enough elements so that when the Moon was formed in the Epoch of Planetesimals, it recieved much of the same elements as the Earth.

Lets say it had just a little less iron than Earth, but made up with it in 2% of its composition devoted to Titanium (as it is RL). Less Silicon, more Magnesium, more Nickel, more Sulfur, less Aluminum but still more than on Earth, ect. ect. We have drawn out a Moon with five times the percentage of Titanium and five times the percentage of Aluminum than Earth, but otherwise with the same composition as Earth (lacking just a little in Iron). Its covered with an ocean, but not as much water as Earth, maybe 10% less.

Now, to make things easier, let's say that the Earth did not have any different gravitational effects than RL, and that history continued exactly the same, except that it featured a different view of our moon (green/blue instead of gray/white).

How would you paint the life on Luna? The history? A sentient species, of course! What happens when the first contact occurs, when the Lunar sentients discover radio technology and are able to pick up signals and send ones of their own? Or when telescopes are powerful enough to look at each other? Would space travel technology quicken? Would humans try to dominate Luna for its titanium sources, spurring new colonies and space trade?

The problem here is that the moon wasn't created seperately from the earth, it was expunged from the earth when the earth was hit by a massive planetoid eons ago.

The moon is much too large to have just formed seperately and then been caught by the earth and put into orbit.
There is no feasible way you could ever have a moon with a similar mass to ours with life on it. Essentially, gravity is too weak, and the atmosphere would fairly rapidly escape into space. If the moon was somehow terraformed today, it's atmosphere would only last a few thousand years for example. A larger moon would lead to larger tides, more earthquakes and tectonic activities, and basically way too different of an earth to have actual history take place.

Mars actually is a possibility though. If Mars was, say, twice its current mass, it should retain enough of an atmosphere to have liquid water and the like. Harry Turtledove acutally explored the idea of an alternate mars in 'a world of difference'

Even if there was an inhabitable moon (or Mars), evolution would probably become totally unrecognizable fairly quickly. Bacteria can survive through space, so asteroid strikes would cause chunks of each to hit the other, meaning that at least the microfauna would be totally different on Earth, likely leading to different diseases, and a totally different evolutionary direction.


eschaton said:
There is no feasible way you could ever have a moon with a similar mass to ours with life on it.

No, it'd be easy. Force of Gravity = G(constant)*(mass one)*(mass two) / distance^2.

So then you set OTL's equation equal to the ATL's equation:
G*(mass of OTL moon)*(mass of earth) / (distance from moon to earth)^2 = G*(mass of ATL earth and moon, which is the same)^2 / (distance from moon to earth)^2

then you cancel stuff out and get

(mass of OTL moon) / (OTL distance between earth and moon) = (mass of ATL moon) / (ATL distance between moon and earth)

and put in the real values (weights are in kilograms and distances are in kilometers)

(7.475e22) / (384400)^2 = (5.9742e24) / d^2

d = 3,436,510 km

so the ATL moon would have to be orbiting roughly ten times farther away than today's moon for it to have identical gravitational effects.


Well, that blows my idea out of the water. Are you sure there is no possible way for the Moon to have an Earth-like atmosphere and remain the same size?
Not even with all-iron like Mercury...

Sorry, just too small, unless you invoke ASBs to fill the core with Unobtanium so ~5 times current mass. Then Moon needs to be further out, but it would be anyway due ancient tidal energy dissipation.

( Some of our fossils saw 20 hr days & 21 day months... though perhaps not together ;-)

Ask ASBs to put Venus in equilateral 'Trojan' position, with Vespa as a moon.
Well, that blows my idea out of the water. Are you sure there is no possible way for the Moon to have an Earth-like atmosphere and remain the same size?
Yea. I can confirm that. The gravity is what keeps the lighter air molecules from drifting out into space. The current composition of the lunar atmosphere, as measured by Apollo 17, is Neon, Helium, and Hydrogen in roughly equal amounts. Most of this came from the solar wind. Other gasses that may have originated within the moon (argon 40, carbon dioxide, methane) are in much smaller quantities. The atmosphere is also not in nearly the density as that of Earth.

As a point of comparison, look at our atmosphere and that of Jupiter. Earth has gases such as Nitrogen and Oxygen in large quantities. Jupiter, on the other hand, has a lot of hydrogen. Because of its size (and distance from the sun) Jupiter can retain the hydrogen.


Hmmm... well, in that case, let's just say that the ASBs created a machine in the center of Luna's core that is roughly the size of a dime. It creates an energy field that surrounds the Moon, composed of a peculiar energy that can hold in an atmosphere. As in, lighter air molecules cannot get passed it, but all other molecules can. The energy field doesn't affect anything other than the atmosphere, keeping it regulated as if there was Earth-like gravity, though the gravity remains 1/6th that of normal.

Also, the Moon has a more Earth-like composition, more than three times as much iron than RL. It also has significant sources of Titanium and Aluminum, and its surface is covered with water of which is the same on primordial earth.

Luna doesn't have tectonic plates, does it? So continents couldn't just form, they'd have to be there from the start. Let's say that 80% of the surface of Luna is covered in water, primarily. Can anyone help me make a map for that?

Otherwise, any suggestions on what an interesting course of the history of the Moon would be if the aforementioned changes were made. I think that evolution would favor organisms that could use the Moon's gravity to their advantage, and thus, there would probably be a lot of aerial creatures. Those that are faster and can follow the sunlight instead of freezing to death in the Lunar Shadow would survive as well. Creatures that can burrow or protect themselves from the extreme cold and extreme heat would survive as well.

What would a sentient species look like if they evolved on the Blue Moon?

Nice name, by the way, I think I'll keep it. The Blue Moon.
You don't need to have a total ASB machine to keep an atmosphere in. All you need is to float down a film a molecule thick to lay on top of the atmosphere and stop it from drifting out. Maybe leave a few holes near the equator so that ships could get in and out. That should suffice.
It could have an atmosphere underneath the surface, along with water and such, but other than having it be smaller and closer to share an atmosphere with earth I can't think of many ways beyond that.
Ok, how about a colony map were Mars and Venus are both habital with WW1-type powers (Meji Japan, USA, Great Britain, Imperial Germany, Austria-Hungry, and White Russia.)...What? :eek: It's a dream isn't it?

Assuming a second habitable planet in our solar system, and that they both develop life, I'd expect it to be long odds that they both develop sentience at the same time, let alone technology.
First of all, there's the question of weather muti-cellular life is even a likely result of life in the first place. Even if it is, it took hundreds of millions of years for for multi-cellular life to evolve into sentient life, let alone technology using life. Assuming (and even this is unlikely, IMHO) that life gets started at the same time, a variation of .1 percent in the time it takeds to develop sentiance is several hundred thousand years. Onne planet will likely develop technology before the otehr develops intelligent life.
The other planet will, IMHO, never evolve intelligence once it's colonized. A ruthless species will carelessly kill off many species--and a more ecologicly careful one will manage the ecology, but will still seriously squeeze the area avaialble for the native wildlife. The gene pool shrinks, and a managed ecology is not a good ground for evolution anyways, I'd think.
Or we could say that all life is in our solar system because of aliens. Which I think is far more likely than a blind evolutionary path. I just want a desent believable timeline without ASBs were we have WWI in space. Colonies on Luna, a bronze age on Mars, a ruthless jungle on Venus. Multiple PODs I know would have to take place long ago.


Wow, that's an awesome map!

I wonder what you need to do to merge it into one full map... Anyone have some cool Photoshop skillz? Something like this: http://www.redcolony.com/features.php?name=map

That is also an awesome map, right there.

There's an idea. What if the entire Moon is submerged? Could there be an atmosphere for some kind of life under the Lunar Ocean?

Wow, the Selenites are really cool. But I have a faint belief that evolution on the moon would benefit quick, flightly creatures, able to use low-gravity to evade predators and catch prey. Then again, if there were sentients, they would definitely need something to manipulate objects. And, they would either need to be able to burrow or migrate quickly to escape the cold periods of the Moon.

Then again, if there was an atmosphere in the Moon, the heat would be dispersed, correct? Only during the Lunar Eclipse would the surface be completely shadowed, and the atmosphere grow icy. During the New Moon, the extreme heat from the sun would disperse around the globe.

Subject to more debate.
ah, so more of a victorian view of space was correct, huh?

that gives me so many ideas... i had done stuff about i mixed universe, of scientificly accurate victorian space life. in the middle of Australia dr Bland, invetor of the airship (in OTL he did designs, but the Brits didnt take him seriously) crashes in the desert and finds a strange glowing green substance, a sort of uraniam substance. he gets it tested, and if you apply ?water? to it then it produces great ?energy?. i even had drawings of the creatures, and who colonised where. i am inspired to continue it

Darkest90 said:
Here is an awesome idea that I would like to see worked out. What if Luna had nearly the same composition of the Earth? Some fluke in the Big Bang provided enough elements so that when the Moon was formed in the Epoch of Planetesimals, it recieved much of the same elements as the Earth.

I am afraid it is true that the Moon is too lightweigth to keep an atmosphere. :(

However, having life, especially sentient on another planet in the Solar system is an interestring possibility.

First fo all, I find it very unlikely to have two sentient civilizations develope at comparable rate on two different planets. So the situation with the radio-contact between the Earth and the Moon civilizations described above seems unlikely. BTW, even if they coud exist, most likely they would dicover each other after they invent the telescope. Somebody - Gallileo? - was proposing to draw large geometric figures in the deserts, to lighten them with fires just with the purpose of establishing contact with the selenites....

I find it a more likely situtaion a contact of two unequally developed (technologically) forms of life, i.e. an advanced civilization finding bactearias on another world or just primitive "savages"... We all know from history what happens in thsoe cases. Of course, the habitability for each of them may be so different, that there won't be much conflict of interest for leibenstraum (spelling?) but the more advanced may still need the iron, the plutonium, etc. from the world of the others.

A non-sentient life on another wold is actually a possibility even in OTL and the microbial exchange with Mars was claimed a few years ago (albeit the evidence is far from convinsing), so this may prove not to be an ATL...