New answers tagged earth
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Counter-Earth is too massive to stay in any of Earth's L points. As Theraot points out only L4 and L5 are stable for objects much smaller than the main body. Another Earth would be too massive, and also Jupiter is too massive so it would also perturb Earth's L points.
So you need to move Jupiter.
Move Jupiter to Earth's orbit and then put Earth and ...
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Long story short:
From their home planet, the aliens can only determine if a star system contains a planet with liquid water and carbon occurence, but they can't see if the planet is really suitable for colonization.
When the aliens hide from humans, they can live on earth for a long time, but since humans are a pretty aggressive species, the aliens wouldn'...
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Quite a lot.
From a quick internet search I have found this
a ring of 480,000,000 copper dipole antennas (needles which were 1.78 centimetres long and 25.4 micrometres [1961] or 17.8 micrometres [1963] in diameter) was placed in orbit to facilitate global radio communication.
More in detail
The US Military launched 480 million copper needles into ...
answered Nov 28 at 7:00
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Among mammal species, there are a small percentage with bodies large enough to support large brains. Among mammal species with bodies large enough to support large brains, a minority do have large brains, brain comparable to human brains in size.
That leaves about a hundred or so species of mammals on Earth with brains, and possibly intelligence levels, ...
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Since your query specifies a civilised species, rather than a species possessing intelligence, awareness, soul, imagination and the like, I'd posit that such species already exist.
Or are very close to it.
A civilised species should have, according to human definition, a highly developed society or culture; refinement in taste and manners; or evidence of ...
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Some type of monkey, likely an ape (since they're better on the brain front).
But it's not just brains that you need. I don't think it's possible to overestimate how important hands are for our civilization. Boiled down far enough, any tangible result of science is just advanced tool use, and our hands are unmissable for how we are doing that.
Almost as ...
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In short term (millions of years), most likely already long living, somewhat intelligent and social species with free hand-like manipulators. In longer term (hundred of millions years), pretty much anything can change.
So, in order of decreasing probability:
Genetically engineered (uplifted) animals with hands. Monkeys, apes, maybe hamsters, ferrets, ...
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I think next pretender would be some ape, orangutan maybe. They some of necessary things to create something of civilization. Apes have dexterous hands, quite big brain, can use tools, have social lives.
On Earth we have also other smart and/or social animals, but most of them lack something essential. For example dolphins are very smart, but their fins and ...
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The program included in humanity has, in reality, infected all of it.
In fact, it was included in some of humanity precursors, hence the missing link that will never be found.
The aliens know that.
They just don't understand how a though-calculator that render its victims somewhat unpredictable and violence-prone could create such a fast-evolution specie (...
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Because they need the humans as they are
What if the aliens realize that using human subconscious makes for the best computational device they could ever develop? The human brain is particularly efficient in running the computational models that these aliens have invented, to the point that none of their computers would ever be able to outperform it.
In ...
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There are a number of factors that could make Earth not suitable to be their long term home.
Gravity - too low or too high could cause significant biological changes over time to the point where they don't consider themselves the same specie any more. That could be a very high psychological / ethical threshold to cross and might be enough to send them ...
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Earth was never the final destination
It was designated for a stopover, for refueling, servicing, or recuperation.
This is continuing and inspired by the kadu's answer, but adding quite enough ideas to be a separate answer.
Main condition
Perhaps FTL travel technology allows travelling only a limited distance. And even with FTL travel, the travel may be ...
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They are altruistic
They recognize that life deserves a chance to thrive, and an intelligent species deserves the right to choose its own path. Humanity is still a fledgling race, so the aliens do not intervene. The computations done subconsciously don't affect our genome, so have no long-lasting negative consequences. Their calculations are for a place ...
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When the aliens "discovered" and calculated the habitability of earth (from x light years away) - even with FTL we can assume that travelling here took them years - if not hundreds of earth years. At that time earth was in our "medieval age" - total population probably around a low hundred million - no noteworthy military danger - intact ozone layer, clean ...
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I would think there are two reasons why the aliens have not colonised earth.
While technologically superior, the aliens are biologically inferior to humans, and humans exist in much greater numbers. Meaning that there are equal chances of either losing a war, or destroying earth in the process, or winning. So they would rather not risk a confrontation.
Even ...
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Other posters here have come up with reasons not to colonize that are friendly to Earth's resident human population. I'm going to take a darker tack:
Earth is doomed
Why colonize a planet, if it's only going to be around for the next 1000 years?
Human scientists haven't figured out that the sun will go nova shortly, but the aliens have.
The aliens ...
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Our environment is lethal to them. Too hot? Too cold? Oxygen as one poster suggested? Some pollen or the like, it doesn't matter.
The ones here running things are in MOPP-5 (chemical warfare suits) or even space suits any time they aren't in their base.
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Solar flares
The problem is not Earth, but the neighborhood.
In the search for perfect place to settle, so much attention got on the planet side of things. The alien's sun has the most perfect, calm and stable sun -- and everyone's sun is like yours, right?
So it's come to a shock when they arrive and warp stop working and communications is unstable, all ...
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Earth makes them sterile
It's a variation on other answers, but something about Earth, its atmosphere, magnetic field, radiation, bacteria etc makes the aliens sterile.
So while a sacrificial few can live down on the surface for the sake of the mission with no other noticeable ill effects long term colonisation is out of the question.
These surface ...
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The aliens evolved on a planet without a magnetic field, and Earth’s magnetic field makes them falling-down dizzy. They can manage temporarily by wearing equipment that senses and cancels Earth’s magnetic field in their immediate vicinity, but it’s bulky and imperfect and not a good solution for a long term colonist.
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Why go to science fiction, when there are real-world examples today, why humans don't want to go to the Moon or Mars for extended times?
Bone strength.
The alien's home is a 7g planet. They can live on 1g Earth for a while, but over time their bones get too weak, their blood vessels expand, and all the other ailments that humans have to recover from when ...
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1. They actually cannot live on Earth for extended periods of time
Your premise is that Earth should be a candidate, since:
"[...] some have been on Earth for 20 years. [...] Clearly they're capable of living on Earth for extended periods of time, but for the story I need them to have ruled out Earth as their home the moment they arrived. "
However, you ...
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Just fast forward our current real-life state of Earth a little bit:
Pollution. The Earth is so full of plastics and trash and smog everywhere, and getting worse daily. Also the resources of Earth are too mostly depleted, making it not a viable target for mass colonization. (why expend all the FTL resources to get to place that is in same of even somewhat ...
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A) The aliens are hypersensitive to gravitational changes, and find the moons slight gravitational effects (which can lift water, dont forget that) nauseating. So after the invasion, they discovered, that every half moon orbit, they conquered a planet that makes them vomit. They try to protect themselves in there ships, but if you are living in a ship anyway-...
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Answering the question "Why would most of the aliens live on a mothership orbiting Earth instead of on the surface?" from the OP, not the question "Why would Earth be long-term unsuitable for these aliens?" from the title.
Their ship might simply be more comfortable for them, with all their alien structures and alien luxuries. They might not be able to ...
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"It's the smell!"
-- Smith
I think the easiest answer is that there is something in Earth's biology that disagrees with them... something that can be "managed" with continuous medical intervention, but would be really annoying for them to try to settle permanently without completely terraforming the planet. Imagine, for example, that 99% of the aliens ...
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This was the result of First Contact
For whatever reason, these aliens do not want to invade, conquer, or otherwise subjugate us under their rule. However, they need our brainpower in order to move on. So our first contract with them resulted in a trade once the language barrier was resolved: They assist us in advancing our technology along reasonable ...
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The aliens are humans.
The aliens did do the calculations and they did find a habitable planet, 100,000 years ago. They are depleting their homeworld - here.
On arriving on Earth and settling the colonists, the mothership immediately started working on finding the next world. These calculations take a very long time.
Almost none of the humans on ...
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The aliens evolved on a planet on which photosynthesis never developed. Oxygen is a poison to them. Some of their least susceptible adults can handle it for limited periods of time with medical support. Earth is not a healthy place for them long term and they cannot raise their children in our atmosphere.
Removing the oxygen would be particularly difficult, ...
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Perhaps microbiological life is more rudimentary or non-existent on their home planet. When they arrive on Earth the microbiological biosphere becomes very apparent to them and they can’t compete with it.
Perhaps the aliens who do come down to Earth can survive but there are big issues with contamination that they have great difficulty in overcoming. Maybe ...
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The aliens may have decided that their time on Earth should be minimally invasive to humanity. Although they're tagging humans and using us to solve their distributed computing problems, for the most part they're allowing us to go about our day-to-day lives without undue interference. Obviously, colonizing our planet is going to be much, much more invasive ...
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Alien's biology is very different from Earth lifeforms.
Their disguise is a very complex process requiring a different biological body, similar to the premise in "Avatar". They can't live on Earth, and they don't envy human bodies either, so it's better for them to stay isolated.
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Depends on what you mean.
The initial impact would have made it difficult for a while but if you are talking about how long it took for things to go back to a reasonable level for human-level species to survive, it would be something in excess of 4 million years according to the Washington Post:
https://www.washingtonpost.com/news/speaking-of-science/wp/...
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Likely what killed everyone was the nuclear winter that took place after the impact. The impact itself was likely not that big, maybe a crater around 6 miles wide. The thing that killed everybody, however, was the winter from the ejecta and etcetera. The amount generated from a volcano is enough to screw over lots of people for weeks, if not months. An ...
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It's possible, but very, VERY costly, and not environmentally friendly at all.
Because of the inconsistencies of solar and wind, massive batteries would need to be built to accommodate conditions such as still air, and night. Lithium is extracted through pit mining, like copper, so massive mines, and environmental damage.
additionally, a very ...
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It's simply a matter of priorities. Let's focus on the United states because we have good studies for this area. An analysis by the energy research firm Wood Mackenzie, finds that that shifting to 100% renewable over the decade would cast 4.5 trillion. The US federal budget is $1.2 trillion for discretionary spending (per year) so this number is doable (if ...
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The game with renewable energy is that it's always windy somewhere, the sun is always shining somewhere, somewhere always has geothermal, somewhere always has waves, somewhere always has water in their dam. The larger your power distribution network, the more stable the supply and the more stable the load.
It's not about localising, it's about spreading ...
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I suspect that you would use a wide range of sustainable energy sources, ranging from wind and solar to wave energy, tidal energy, geothermal energy, and biofuel (first and second generation). This variety will reduce the overall lows and peaks in production.
You would probably see a lot of wind farms (many offshore) and solar farms, but also a lot of solar ...
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Is that possible with current technology and resources?
No. With current technology this is not possible. Some places don't have flowing water (no hydro), or enough sunlight (which is everywhere during night, or places with lots of clouds), or enough wind, and so on. One of the biggest issues with renewable energy sources is storing the energy during off-...
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I'm assuming Nuclear is "Non-Renewable"
The world would probably look a lot more localized, at least from a power generation point of view.
Most renewables have a lower energy density to non-renewables. So without the existing national grid, why would you create it? It would be as efficient to have each local district (or even house) have their own ...
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According to median IPCC models barely noticeable difference for a random observer:
plus 2-3 C (most of the increase during nights, winters and near poles)
less than meter higher ocean level
clearly more heat waves, with other extreme climate events the models are unclear, but they are likely
If for story reasons you need some doom, then I suggest picking ...
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This is not my expertise, but I used to be climate skeptic as a teenager(yeah, I know, I'm sorry, I was a teenager, ok? kek), who later actually sat down and read a bit about it, so I'll tell you what I understood. Climate change is actually much slower of an extintion effect than most media and activists would have you believe. From what I've learned, it's ...
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