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Astronomers Say Dying Sun Will Engulf Earth
iamlucky13 writes "A minor academic debate among astronomers is the final fate of the earth. As the sun ages and enters the red giant stage of its life, it will heat up, making the earth inhospitable. It will also expand, driven by helium fusion so that its outer layers reach past the earth's current orbit. Previously it had been believed that the sun would lose enough mass to allow earth to escape to a more distant orbit, lifeless but intact. However, new calculations, which take into account tidal forces and drag from mass shed by the sun, suggest that the earth will have sufficiently slowed in that time to be dragged down to its utter destruction in 7.6 billion years. "
Wow...talk about global warming!
No Sigs!
All good things...
But maybe replicating space organisms that live in the Oort cloud will come and put a protective membrane around the Earth before then slowing down the passage of time on Earth in relation to the rest of the galaxy so we can be united with other sentient beings in worlds connected to our own by giant arches poking out of the sea.
Ahh, Robert Charles Wilson, you Spin me right round.
How we know is more important than what we know.
Heck, 7.6 billion years is ok by me; Chun the unavoidable will have been at my elbow by then.
This is the way I was taught it would happen on astronomy shows from the 1980s. I don't get the big deal.
The government can't save you.
This isn't news at all, in fact I haven't heard anyone say it would happen any other way. I think I have a "My First Picture Book of the Planets" that says the same thing.
And to find this out the day I discover my paxil/zoloft/venlafaxine does nothing.
Beer me.
In 7.6 bln years time frame there is a 99.9 probability of a massive object hitting Earth and melting the outermost solid shell.
Hmmm... a 7 digit user id... you must be old here.
Accelerate Earth to put it into a wider orbit. This will solve Global Warming and the Earth being swallowed all in one.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
32.823352272542484276756074858822 + 1 bits, so 5 bytes
And some of the academic references are actually a decade old: http://www.astronomy.ohio-state.edu/~pogge/Lectures/vistas97.html
Or just build lots of robots and have them all vent out their exhaust pipes in the same direction at the same time.
...humans will have destroyed it, and several others...
7.6 billion years? If people are still H. sapiens then it'll probably be throwing out some theories too, since current theories posits we were only minor fauna running around in the footprints of dinosaurs merely 80 million years ago.
After 7.6 billion years, it's time to move out of mom's basement.
By that time, mankind will be sufficiently advanced to relocate to an outer planet.....like Pluto.
What? Pluto isn't a planet anymore??
Oh No! We're doomed!!
Have gnu, will travel.
Nonsense. All testing is done by capable and brilliant scientists, now back to my experiment.
Uh, it's probably not a problem, probably, but I'm showing a small discrepancy in... well, no, it's well within acceptable bounds again. Sustaining sequence.
Most people aren't thought about after they're gone. "I wonder where Rob got the plutonium" is better than most get.
During the hydrogen burning phase, inert helium gradually builds up in the core and hydrogen becomes less common. This means the core has to contract and become hotter in order to produce enough energy to support itself and the surrounding envelope. The fusion rate depends on the square of the hydrogen density (since you need the hydrogen atoms to collide with each other), so if the hydrogen density goes down, the core has to become hotter and more generally dense in order to maintain the same energy production rate. (This is why stars gradually become more luminous over their main sequence lifetime, as the core actually has to produce more energy in order to support itself in its more compact configuration.)
As a star finishes exhausting its hydrogen, this actually reaches a very extreme configuration where the core becomes much more compact (and much hotter) trying to squeeze out the required energy with very little hydrogen remaining. The total energy being produced by the core (in order to keep itself from collapsing) increases very rapidly at this point, and the larger luminosity will then push the envelope outward, puffing it up. This is why stars expand into red giants, and this is the stage where the Earth will probably be engulfed.
For trivia purposes, the central core eventually runs entirely out of hydrogen and sits there as an inert clump while the upper edges of the core burn hydrogen. When the hydrogen is exhausted for a large enough fraction of the core, the center eventually becomes hot and dense enough to fuse helium into carbon. At this point, the overall luminosity drops again (because the star doesn't need to keep frantically burning just hydrogen to support itself) and the star contracts a bit. The process then starts over again, with a shell of helium fusion surround an inert carbon core that (for stars more massive than the Sun) eventually ignites to fuse into neon, oxygen, etc.
Microsoft delenda est!
When speaking of planetary catastrophe the death of our Sun is but a distant worry. It has already been mentioned that in about 3 billion years the galaxy Andromeda will collide with our own Milky Way galaxy. That of course poses several dangers to Earth in itself, though none particularly likely due to the vast distances between stars within galaxies, the potential for a stellar marauder to interfere with our solar system and cause chaos for Earth does exist. More worrisome, though, is the fact that around the same time (3 billion years from now) the Earth's core will finally cool and it's magnetic field generating dynamo will shut down, causing the Earth's shielding from the solar wind to collapse and the atmosphere to be stripped away eventually leaving the planet as dry and barren as Mars. Well before that ever happens, Earth will have to deal with the solar system's bobbing and weaving in and out of the galactic plane, possibly exposing the planet to deadly cosmic rays. Even nearer to our future is the fact that a conveniently aimed gamma ray burst from an exploding star (Betelgeuse is ready to go any day now) could "sterilize" the planet. Then of course, there is the ever present threat of an Earth shattering asteroid impact, which happens every 100 million years or so on average... in which case you could consider Earth overdue for another one. So yeah... the Sun engulfing the Earth (or what's left of it) 7 billion years from now... I wouldn't sweat that one.
According to the professor who taught my astronomy class, the Earth's climate will be tipped into thermal runaway, like Venus, long before the Sun becomes a red giant. Solar output increases steadily as the Sun ages. It's only a matter of time, like a few billion years, before it overwhelms the Earth's ability to regulate its temperature.
Mea navis aericumbens anguillis abundat
How in the Hell is this NEWS?! Astronomers have known about this for DECADES!
What's next? An article telling us gasoline is flammable?
Somebody please tag this noshitsherlock.
Knowing Google's lust for data collection, the Soviet Union is still alive and well inside the psyche of Sergey Brin....
> someone will do something crazy or stupid and destroy the entire planet.
Panel member: If you were to meet these Vegans, and were permitted only one question to ask of them, what would it be?
Ellie Arroway: Well, I suppose it would be, how did you do it? How did you evolve, how did you survive this technological adolescence without destroying yourself?
Nostalgia isn't what it used to be.
Only by laypeople, as far as I know. For as long as I can remember in modern astronomy, it's been thought that the Earth (as in the big hunk of rock, not any of its fancy accessories like say, life, or water... minor but important point there) would actually survive, barely. Scientists generally believed the mass loss from the inflating, overpressured sun losing its grip on its outer atmosphere would be sufficient to allow Earth to escape destruction as its orbit would be slowly spiralling outwards while the sun lost mass. It would still ultimately end up being far too close to the inflated sun not to be burnt to a crisp, but the rocky body of the planet itself would survive. Now it turns out the drag from all that mass being lost would be enough to slow the Earth's orbit down to the point where it would indeed be consumed.
Random and weird software I've written.
The solar corona problem isn't tied to fusion per se, just to a very hot core cooling radially outward. Also, there aren't any problems with thermodynamics in this situation provided there is some mechanism that is adding energy to the plasma at the solar surface. Given the violent nature of the solar surface, particularly with respect to solar flares and coronal mass ejections, there are certainly energy generating processes going on, so it isn't too terribly surprising that the corona gets heated up. The big question is what process(es) are causing it. For what it's worth, magnetic reconnection is the main suspect.
Back in the 60's or so they figured out the whole red giant phase of stellar evolution and realized the sun would expand to about the diameter of the earth's present orbit when it reached this point. It was a fascinating bit of trivia for Carl Sagan and the common folk to pass around that the sun would engulf the earth, but further investigation showed the sun would likely lose something like 30% of it's mass as heat from helium fusion blew away the outer layers (a process that looks really freaking cool from a distance). This would cause the earth, due to conservation of its orbital energy, to assume a much larger orbit...about as far out as Mars is today.
Therefore the popular notion was thought by many astronomers to be wrong. But in fact, nobody had ever done a really detailed model of the process until the subject of this article. It turns out, the professionals were wrong, and the common folk were correct, if only because we were a couple decades behind the times academically.
If you don't believe me, here's the archived wikipedia page for earth from last Friday. It's since been updated.
Space is big. There are only supposed to be about six stellar collisions, and most of those in the core region. Out here in the boondocks? We're probably fine.
I am a science fantasy fan
the core of the Sun is more like 15 million degrees.
the coronal heating problem simply means the mechanism responsible for the increased temperature is a non-equilibrium process. the corona is also a near-vacuum so despite its high temperature there is relatively tiny amount of energy there.
We learnt this in science in the 80s. It's probably older news than that. So what if there is a new calculation, does 7 billion years away really matter?
Analytic & algebraic topology of locally Euclidean meterization of infinitely differentiable Riemmanian manifold
If evolution is a myth, what chance does gravity have? It is also, after all, only a theory.
"Evil will always triumph over good, because good is dumb." - Dark Helmet (Spaceballs)
Unless there are some revisions in the laws of physics, the nuclear processes throughout stellar evolution are well known based on computer models.
When helium "ash" accumulates in the core, helium fusion is not the next thing that happens. The core starts contracting and heating up, but that lights off H2 fusion in the shell surrounding the core. That phenomenon changes the luminosity and heat transfer rates of the star, causing the outer atmosphere to swell up into the red giant stage.
When shell burning runs its course, again the core contracts and heats up some more, resulting in the helium flash. Based on computer models, the helium flash is a major disruptive event caused by the sudden onset of helium fusion, it does not cause the star to go nova or anything, but it causes the star to change modes as it were, becoming somewhat bluer and smaller, but still more luminous than Main Sequence. From the computer models, it is believed that the upper-righthand HR diagram stars, red giants, are H2 shell burners while the horizontal branch above the Main Sequence represents He core burners.
For a massive enough star, exhaustion of core He will initiate shell He ignition, sending the star back into the red giant range, perhaps as a red supergiant for a massive star.
The red giant phase is only one phase of an evolved star. Everyone just kind of assumed that a star that goes supernova would be a red giant, but it seems like the star that popped off in Supernova 1987a in the LMS was blue.
For empirical evidence, I'll note that one of us sounds like a pedantic nerd with a tweed fetish, while the other is currently modded at +5. Just saying.
Microsoft delenda est!