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View Full Version : Are humans still here....when our sun goes NOVA....???......



Hazzard
2005-Apr-02, 11:18 PM
Let me take you with me down the coridores of time......(yes i know).

When is our planet is not sutible for humans any more..our star going nova and all...?

Im serten that we would have had enough time to get of the planet.as a species...but were is the closest "earth like planet"...???

The year now is 2005.April 3d...And we just dont know.!!!


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Our own solarsystem is OLD....

Our sun (when getting an attitude) will make this starsystem impossible to grow potatos in. :wink:

Who knows....Europa might get Bahama in 3BY... 8)


Reincarnation anyone.. :D

01101001
2005-Apr-03, 12:10 AM
When is our planet is not sutible for humans any more..our star going nova and all...?
Nova? Why?

Andreas
2005-Apr-03, 12:22 AM
Our star won't be going nova. And not supernova either.

The question about when our planet will not be suitable for humans anymore is a difficult one. We can use technology to survive in hostile environments so that's pretty much impossible to predict.

Natural life, without technical assistance is slightly more predictable. As the sun will continue to increase its brightness, Earth will become hotter and the atmospheric composition will change. The absorption of carbon dioxide will lead to the extinction of land plants and most higher lifeforms in about 800 million years. In about 1.6 billion years even there is not enough carbon dioxide for photosynthesis of even the simplest organisms in the oceans. The only survivors will probably be chemosynthesizing bacteria, until the oceans dry out.

And that's long before the sun will do all its interesting end of life stuff, like turning into a red giant.

Brady Yoon
2005-Apr-03, 12:39 AM
Our star won't be going nova. And not supernova either.

The question about when our planet will not be suitable for humans anymore is a difficult one. We can use technology to survive in hostile environments so that's pretty much impossible to predict.

Natural life, without technical assistance is slightly more predictable. As the sun will continue to increase its brightness, Earth will become hotter and the atmospheric composition will change. The absorption of carbon dioxide will lead to the extinction of land plants and most higher lifeforms in about 800 million years. In about 1.6 billion years even there is not enough carbon dioxide for photosynthesis of even the simplest organisms in the oceans. The only survivors will probably be chemosynthesizing bacteria, until the oceans dry out.

And that's long before the sun will do all its interesting end of life stuff, like turning into a red giant.

800 million years? I thought the steady mass loss of the Sun would cause our orbits to enlarge to the point where we'd be reasonable safe.

How will carbon dioxide be absorbed?

This is an cool post, lots of info. :)

Chip
2005-Apr-03, 02:04 AM
...When is our planet is not sutible for humans any more..our star going nova and all...? I'm certain that we would have had enough time to get off the planet as a species...but were is the closest "earth like planet"...??? The year now is 2005 - April 3d...And we just don't know!!!...

Very much less than 800 million years is more than enough time for us to invent the Atavachron (http://www.startrek.com/startrek/view/library/technology/article/70025.html) or Warp Drive (http://www.nasa.gov/centers/glenn/research/warp/warp.html), and get outtah here before the Sun gets too hot.

But long before the Sun affects Earth, human beings will likely evolve
and/or become extinct. (All species become extinct eventually. Got to make room for the next model!) :wink:

mickal555
2005-Apr-03, 07:28 AM
I don't think that much mass is lost until it goes PUFF

remember E=mc^2

C^2 is really big!

Hazzard
2005-Apr-03, 02:18 PM
Our star won't be going nova. And not supernova either.

.

Why not..??

And why do only some stars become Novas.?? :-?

Eroica
2005-Apr-03, 02:33 PM
Novae (http://www.aavso.org/vstar/vsots/0501.shtml)


Novae belong to the class of stars known as the Cataclysmic Variable (CV) stars, along with the dwarf novae, recurrent novae, nova-like, and polar (magnetic) variables. And like all CVs, the physical system is comprised of a very close binary pair, with a white dwarf star as the primary component and a Sun-like, main sequence star as the secondary.

Short answer: our Sun is not part of a binary system, so it can't go nova!

Nick
2005-Apr-03, 02:40 PM
Also, at current trends, humans will kill all life on this planet anyway within a few 100 years, let alone worrying about the sun dying in 800 million years.

Nick

Russ
2005-Apr-04, 01:03 AM
...When is our planet is not sutible for humans any more..our star going nova and all...? I'm certain that we would have had enough time to get off the planet as a species...but were is the closest "earth like planet"...??? The year now is 2005 - April 3d...And we just don't know!!!...

Very much less than 800 million years is more than enough time for us to invent the Atavachron (http://www.startrek.com/startrek/view/library/technology/article/70025.html) or Warp Drive (http://www.nasa.gov/centers/glenn/research/warp/warp.html), and get outtah here before the Sun gets too hot.

But long before the Sun affects Earth, human beings will likely evolve
and/or become extinct. (All species become extinct eventually. Got to make room for the next model!) :wink:

I have to agree with my good friend Chip. By the time the Earth is inhospitable to humans, there won't be any humans. There may be some unrecognizable decendant of humans but nobody you know will be around. ;) :D :lol:

WTP
2005-Apr-04, 02:02 AM
I'm a little more optimistic.

By the time the sun is ready to go nova, technology will be able to stop it. If it comes to it, we'll destroy entire stars to save our own star. That, or we just move the Earth somewhere safe.

How? I have no idea, but if we got from the computer to the Internet in 50 years, imagine what we'll have in 5 billion years!

Not that it will matter, as we will all be dead.

Inferno
2005-Apr-04, 02:20 AM
Not that it will matter, as we will all be dead.

Except that I plan to teach my kids to invent time travel, or if they can't teach their kids...and so until the year 5 billion AD. At which time the creatures decended from me will come back in time, pick me up and show me the wonders of the future.

Ha ha ha. It's so simple really.

TravisM
2005-Apr-04, 02:24 AM
Humans won't evolve much as an entire species unless some disaster causes there to be only several thousand beings. Right now, the gene pool is so huge there's little room for any 'enhancement' to breed through.
Now, I'm not saying such a disaster isn't likely, but if we keep up our efforts to prevent impactors from reaching us the only thing we need to worry about is mother nature herself.
The energy required to prevent to sun or move the earth would be enough to move the entire population to a realativley young star. It'd be cheaper. You see, we humans are like water: path of least resistance.
Just my cent and a half.

Bathcat
2005-Apr-04, 10:39 AM
Well, a good candidate for oldest human fossil is 195,000 years old. reference (http://www.sciencedaily.com/releases/2005/02/050223142230.htm)

So 800 million years is somewhere around 4000 times the entire lifespan of our species to date!

And mammalian species usually last about 1 million years, ten million for really static, unchanging species.

Soooooo.....

It sounds like humans per se most likely won't be around in 800 million years. Something might be, but it almost certainly won't look or act or think like us savanna-apes do.

TriangleMan
2005-Apr-04, 11:09 AM
Humans won't evolve much as an entire species unless some disaster causes there to be only several thousand beings. Right now, the gene pool is so huge there's little room for any 'enhancement' to breed through.
Agreed. I think our technological and medical advances have reached the point that it will prevent the human species as a whole from evolving.

Eroica
2005-Apr-04, 11:21 AM
Humans won't evolve much as an entire species unless some disaster causes there to be only several thousand beings. Right now, the gene pool is so huge there's little room for any 'enhancement' to breed through.
But once we begin to colonize planets around other stars that may no longer be the case. Small colonies could be allowed to evolve in isolation for aeons.

Hazzard
2005-Apr-04, 12:37 PM
Humans won't evolve much as an entire species unless some disaster causes there to be only several thousand beings. Right now, the gene pool is so huge there's little room for any 'enhancement' to breed through.
But once we begin to colonize planets around other stars that may no longer be the case. Small colonies could be allowed to evolve in isolation for aeons.

I know this is an old one...but...

That might be the way we got here,on Earth 8-[

John Dlugosz
2005-Apr-04, 03:35 PM
Very much less than 800 million years is more than enough time for us to invent the Atavachron (http://www.startrek.com/startrek/view/library/technology/article/70025.html) or Warp Drive (http://www.nasa.gov/centers/glenn/research/warp/warp.html), and get outtah here before the Sun gets too hot.

In 800 million years, even with sublight travel only we will have colonized the whole galaxy.

Obviously, looking for a near-earthlike planet now is pointless, since the sun its around will be old too when ours is old, and after a few galactic orbits which stars are near will be different.

We need to move to a younger star.

How about ground-level terraforming? A little nudge here and there during planet formation and make sure an earthlike planet is indeed formed!

Swift
2005-Apr-04, 04:05 PM
Humans won't evolve much as an entire species unless some disaster causes there to be only several thousand beings. Right now, the gene pool is so huge there's little room for any 'enhancement' to breed through.
But once we begin to colonize planets around other stars that may no longer be the case. Small colonies could be allowed to evolve in isolation for aeons.

I know this is an old one...but...

That might be the way we got here,on Earth 8-[
I wasn't sure if you were kidding, but there is overwhelming evidence that humans evolved on Earth, and no evidence that we came from elsewhere (another planet's colony).

I do agree that evolution will proceed in different directions for humans on other planets.

Kaptain K
2005-Apr-04, 06:17 PM
I wasn't sure if you were kidding, but there is overwhelming evidence that humans evolved on Earth, and no evidence that we came from elsewhere (another planet's colony).
While it is very likely that humans* evolved here, there is still the faint possibility that life arrived from somewhere else. Panspermia has not yet been completely ruled out.

* Some have argued that H. sapiens arrived very suddenly, with (as yet) no intermediate forms bridging the gap between H. neandertalus and us.

TravisM
2005-Apr-04, 06:24 PM
Well, recently neanderthals have been proven to be a divergant species that lived at the approx. the same time as the forebearers of modern man. :D The neat possibility is that two distinct speices lived on the planet that could imagine, use tools, and perhaps some form language...

Panspermia is still a neat concept but the physics underlying it are poorly understood at best. I don't know how possible it would be for bacteria to survive being ejected from a life bearing planet, ride a rock in a vaccum for an indefinate length of time, then survive the re-entry to another planet, also the impact. The area around the impact wouldn't be very hospitable for bacteria for a time...

All these are just guesses. I'd like to think that life as a chemical reaction happens on any sufficiently chemically diverse world.

Andreas
2005-Apr-04, 06:26 PM
Humans won't evolve much as an entire species unless some disaster causes there to be only several thousand beings. Right now, the gene pool is so huge there's little room for any 'enhancement' to breed through.
Agreed. I think our technological and medical advances have reached the point that it will prevent the human species as a whole from evolving.
Our technological and medical advances also gave us the humble beginnings of genetic engineering. Natural evolution may have slowed down, but once humans start to get genetically engineered on a large scale we will change faster than evolution would be able to.

There's also the matter of integrating pieces of technology into our bodies. For one thing, genetic engineering could be used to improve interfacing technology and biology. Second, pieces of technology may become a large part of people's bodies or may even replace their biological bodies.




By the time the sun is ready to go nova, technology will be able to stop it. If it comes to it, we'll destroy entire stars to save our own star. That, or we just move the Earth somewhere safe.
Again, the sun will not go nova. Once it nears its end of life, it will grow into a red giant, blow off its outer layers over a long period of time and leave behind a white dwarf, for a simplified version of all this. But the real problem (see below) is that the sun has been continually increasing its energy output from the beginning and will continue to do so.




800 million years? I thought the steady mass loss of the Sun would cause our orbits to enlarge to the point where we'd be reasonable safe.

How will carbon dioxide be absorbed?
Okay, I just remembered fragments, so I read that article again. Carbon dioxide is continually cycled. In silicate rock weathering, CO2 combines with calcium and magnesium ions to form solid carbonate sediments. After washing into the oceans, these will submerge into the magma as part of the ocean floor in subduction zones. There it gets broken up again and is eventually released back into the atmosphere through volcanoes.

CO2 is a greenhouse gas and so increases the surface temperature. Since the weathering is increased at higher temperatures, more CO2 gets sequestered. At low temperatures more stays in the atmosphere. This a feedback cycle that kept surface temperatures in a habitable range (at least, water stays liquid) from the early days, when the sun was weaker than now, and will keep it into the future with the sun's increasing strength.

However, it means that CO2 levels are continually decreasing in response to increasing energy input from the sun. At some point, there isn't enough CO2 for plants to keep on photosynthesizing and the food chain collapses.

There are different calculations for when what happens. Refined models also consider that land plants increase weathering of the ground they grow on, there is another storage for CO2 I don't remember right now, and that a part of the plants have developed a photosynthesis chain (C4) slightly different from the normal (C3). The C4 chain continues to work down to 10 ppm of CO2 in the air, whereas the C3 chain stops working below 150 ppm. More effects include the cooling of the earth core, which means less volcanism and therefore less CO2 release and a continually increasing land mass which exposes more and more silicate rock to weathering.

Under these conditions complex land life will not die out due to photosynthesis breakdown, instead it is the rising surface temperatures that will eventually kill them. An average of approximately 30C in 800 to 900 million years will be critical for complex life. Single celled eukaryotes (= having a cell nucleus) might survive up to 45C which will be reached 1.2 to 1.3 billion years in the future. The prokaryotes can keep a food chain going in the oceans by the photosynthesizing cyanobacteria until the CO2 levels drop beneath the C4 chain minimum in 1.6 billion years. Then it's only photosynthesis independent - like chemosynthesis - primitive life forms that may find small niches in which to survive.

That is, until the shallow and warm oceans (surface temperature is at 60C to 70C now) start evaporating on a large scale. Water vapor is a potent greenhouse gas, therefore the additional warming will only increase the evaporation, leading to a runaway greenhouse effect towards 250C, leaving only a hot and barren surface without liquid water.

The research project which provided the calculations based on the refined model can be found there: http://www.pik-potsdam.de/~bloh/evol/

Note that all this happens billions of years before the sun even begins acting up by turning into a red giant and all.


Edit: Adjusted numbers for correctness.

eburacum45
2005-Apr-05, 01:02 PM
Andreas is correct, but I believe the Earth can be maintained at a hospitable temperature until a few (million?) years before it goes red giant.
The Earth will indeed be a hot world long before the Sun reaches a red giant phase - unless we apply some large scale technology.
A sunshade in the Earth/Sun Lagrange 1 point could cut insolation down to any arbritary level; this sunshade could incorporate solar power collectors exporting energy for industry, spacecraft propulsion, life support in space habitats, and computation...
Once the Sun goes red giant the task of keeping the Earth cool will be almost impossible, even though the gradual mass loss of the Sun is supposed to allow the Earth to survive as a planet, if not an inhabited one.

Maddad
2005-Apr-06, 03:00 AM
The Sun's been brightening roughly 10% every billion years on its march to becoming a red giant. Trouble is that it's half way there now in time, and yet instead of another 50% brightening, we will see the sun become 2,000 times brighter. That's a 200,000% increase. What will the shape of that slope be? Do we have say another billion years before we reach the knee?

John Dlugosz
2005-Apr-06, 07:36 PM
* Some have argued that H. sapiens arrived very suddenly, with (as yet) no intermediate forms bridging the gap between H. neandertalus and us.

Not a mystery for a species that had a very small population and was smart enough not to get stuck in tar pits.

Hazzard
2005-Apr-07, 06:32 AM
* Some have argued that H. sapiens arrived very suddenly, with (as yet) no intermediate forms bridging the gap between H. neandertalus and us.

Not a mystery for a species that had a very small population and was smart enough not to get stuck in tar pits.

The first group must have come from somewere!!

Is it totaly OUTTHERE to speculate that someone "dropped them of" on this planet...? 8-[

dvb
2005-Apr-07, 07:36 AM
* Some have argued that H. sapiens arrived very suddenly, with (as yet) no intermediate forms bridging the gap between H. neandertalus and us.

Not a mystery for a species that had a very small population and was smart enough not to get stuck in tar pits.

The first group must have come from somewere!!

Is it totaly OUTTHERE to speculate that someone "dropped them of" on this planet...? 8-[

I think they would have had to drop off not only humans, but everything else living on this planet. If I'm not mistaken, every organism on this planet shares similar DNA characteristics.

Here's some links for you, if you're still not convinced. :D
http://www.hhmi.org/genesweshare/e300.html

http://gslc.genetics.utah.edu/units/basics/bodypatterns/similar.cfm

And a more in depth take on things here.
http://rwor.org/a/1216/gencode.htm

eburacum45
2005-Apr-07, 08:11 AM
The Sun's been brightening roughly 10% every billion years on its march to becoming a red giant. Trouble is that it's half way there now in time, and yet instead of another 50% brightening, we will see the sun become 2,000 times brighter. That's a 200,000% increase. What will the shape of that slope be? Do we have say another billion years before we reach the knee?

I think the gradual 10% per Gya (gigayear) increase will continue while the Sun is still on the Main Sequence, that is right up until just before the Sun goes red giant, a little less than 5 Gy from now.
http://www-astronomy.mps.ohio-state.edu/~pogge/Ast162/Unit3/thesun.html