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Earth's Moon is a Rarity
Smivs writes "Scientists have concluded that moons like the Earth's are actually quite rare. Only 5-10% of planetary systems are likely to contain moons formed by planetary collisions. 'By the time the Earth's moon formed, when the Sun was 30 million years old, the planet formation process in our Solar System should have been approaching its end. In the latest study, Dr Gorlova's team looked at the heat signature of stars using the infrared. This allows astronomers to predict how much of that heat comes from the star itself and how much is re-emitted by dusty material encircling it.'"
What's also rarer is that OUR moon has a face on it. I don't see any other planets having moons with faces on them. So all these other loser planets just gotta admit that our moon is better than their moon.
Side note: In The End of Eternity, we developed time travel before space travel, and so never colonised the galaxy until we eventually discovered hyperspace in the 130,000th century and found that the galaxy was already full of other species and we had no room to expand. Eventually those from near the human extinction altered history to make sure time travel was not invented and thus ensure the expansion into a galactic empire. Apparently the idiots who wrote the sequel trilogy a few years ago failed to read this book (or Robots and Empire), and retcon'd the robots in as Eternals who killed off all competing intelligences in a bizarre and nonsensical addition.
I am TheRaven on Soylent News
Isn't this rather old news? I thought that it was already pretty well known that Luna is rather rare, as shown in the Rare Earth hypothesis?
It amazes me that so many allegedly "educated" people have fallen so quickly and so hard for a fraudulent fabrication of such laughable proportions. The very idea that a gigantic ball of rock happens to orbit our planet, showing itself in neat, four-week cycles -- with the same side facing us all the time -- is ludicrous. Furthermore, it is an insult to common sense and a damnable affront to intellectual honesty and integrity. That people actually believe it is evidence that the liberals have wrested the last vestiges of control of our public school system from decent, God-fearing Americans (as if any further evidence was needed! Daddy's Roommate? God Almighty!)
.. the next time you're out in the backyard exercising your Second Amendment rights, the liberals will see it! These satellites are sensitive enough to tell the difference between a Colt .45 and a .38 Special! And when they detect you with a firearm, their computers cross-reference the address to figure out your name, and then an enormous database housed at Berkeley is updated with information about you.
Documentaries such as Enemy of the State have accurately portrayed the elaborate, byzantine network of surveillance satellites that the liberals have sent into space to spy on law-abiding Americans. Equipped with technology developed by Handgun Control, Inc., these satellites have the ability to detect firearms from hundreds of kilometers up. That's right, neighbors
Of course, this all works fine during the day, but what about at night? Even the liberals can't control the rotation of the Earth to prevent nightfall from setting in (only Joshua was able to ask for that particular favor!) That's where the "moon" comes in. Powered by nuclear reactors, the "moon" is nothing more than an enormous balloon, emitting trillions of candlepower of gun-revealing light. Piloted by key members of the liberal community, the "moon" is strategically moved across the country, pointing out those who dare to make use of their God-given rights at night!
Yes, I know this probably sounds paranoid and preposterous, but consider this. Despite what the revisionist historians tell you, there is no mention of the "moon" anywhere in literature or historical documents -- anywhere -- before 1950. That is when it was initially launched. When President Josef Kennedy, at the State of the Union address, proclaimed "We choose to go to the moon", he may as well have said "We choose to go to the weather balloon." The subsequent faking of a "moon" landing on national TV was the first step in a long history of the erosion of our constitutional rights by leftists in this country. No longer can we hide from our government when the sun goes down.
Bunch of lunatics.
Science advances one funeral at a time- Max Planck
To be honest, I'm not convinced that you can take a SF plot device and run away with it too far in the real world.
1. Radiation. Actually, Earth probably has the least radiation problem in the solar system, because of its strong magnetic field.
Venus, for example, started extremely similar to Earth but was doomed because its dynamo stopped (and was probably weaker to start with). So the solar wind stripped away all hydrogen, leaving it with an atmosphere of CO2.
Mars hardly has a dynamo because its core froze already. Fat lot of good it did for intelligent life there.
Mercury. Ditto. Its magnetic field is at a whole 0.1% of Earths.
So even when you factor in the different mass and conditions, it seems to me like Earth is unique in having too _strong_ shielding, not in needing some plot device to weaken it.
2. (Or 1a.) If allowing more radiation in was better, you don't need a moon for that. Just rotate slower.
(And indeed the way I remember it, the collision theory says that the same collision that created the moon actually accelerated Earth's rotation a lot.)
Or lose your water, which stops plate tectonics, which kills off the dynamo. Easy.
In fact, you need a whole bunch of special conditions to _keep_ your shielding. Losing it seems more like the norm for a rocky planet in the right band to not turn into a snowball. If the moon's positive influence were punching a hole in our shield... heh... then a lot of planets would get there without a moon just as well.
3. Mutations. Longer text, so have patience please.
Well, this is stuff that happens anyway, simply because some UV gets through, there are radioactive elements in the soil, and even because simply errors happen when transcribing DNA. Especially look again at the last parts: even if you kept something under a slab of lead, without UV or cosmic radiation at all, it would still mutate.
Most of the history of life (except for virii, some bacteria and your immune system) was about _preventing_ mutations. Your cells have layers upon layers of defenses against that kind of thing. Starting with the very fact that you're DNA instead of RNA based, and all the repair proteins, and it goes on and on.
Heck, even the fact that you age is a defense against cancer, i.e., against mutation. Your cells start with a max division counter and literally count divisions. So if that mechanism didn't break down too, a tumour would reach a maximum size and stop. Unfortunately that also means that as more and more of your cells reach that limit natuarally, there's more and more damage which can't be repaired, and you discover the fun of old age.
At any rate, any multi-cellular kind of life, actively fights off mutations. Simply because you can't exceed a certain complexity without preventing mutations. You can't have a body consisting of gazillions of cells, if they don't obey the rules. If cells in your palm randomly tried to evolve into a nose, your left foot tried to become a palm, etc, your body would break apart pretty fast.
You also have to understand that this all happens on a "good enough" basis. Your body could evolve even more fool-proof defenses -- and through the billions of years it has, slowly -- but beyond a point they wouldn't be worth the extra complexity and energy requirements. Plus, in the long term, perfect repairs would also mean an inability to evolve. So anything that got too good at it just disappeared later in the next glaciation, when it was unable to evolve.
And in rare cases, even conversely: if it's of advantage to mutate faster (if still in a controlled manner), mechanisms evolve to create just that. E.g., there are cells in your immune system which actively mutate certain genes randomly, to try to produce a protein that exactly matches a target protein. (E.g., a piece of a new virus's capsid.) There's literally an enzyme in there whose sole role is to junk a random codon (think: byte) of DNA, so the repairs would kick in and some of them would get i
A polar bear is a cartesian bear after a coordinate transform.
While it's true that the moon is currently receding, it will eventually stop and begin approaching the Earth, then pass the Roche Limit, break up, and generally cause everyone to have a bad day. However, the universe might not last long enough for that to happen. As for the proto-earth/moon impactor, it was absorbed into the system, with the lighter materials of both it and proto-earth forming the moon, while the two cores sank to the bottom of what became Earth.
Since there are no -1: misinformation in the comment system, I instead reply to your post with wikipedia's article.
Antiope
Orbit of the Moon
Barycenter(Centre of mass)
The amazing thing, to me, is that the Moon's diameter as viewed from the Earth is almost exactly the same as that of the Sun. I've heard that, of the moons in the Solar System, only a handful subtend the same arc as the Sun when viewed from their primary's surface (though of course "surface" is a tricky concept when we're talking about the gas giants), and of those, I don't think many of them are spherical. The kind of diamond rings we get during eclipses are probably quite rare.