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Astronomers Say Dying Sun Will Engulf Earth

kdawson posted more than 6 years ago | from the fire-next-time dept.

Space 343

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. "

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Global Warming (5, Funny)

ChrisGilliard (913445) | more than 6 years ago | (#22569414)

Wow...talk about global warming!

Re:Global Warming (-1, Flamebait)

Anonymous Coward | more than 6 years ago | (#22569440)

Fuck off hippie. A little sad your starbucks was closed for a few hours?

Re:Global Warming (1)

__NR_kill (1018116) | more than 6 years ago | (#22569820)

can't wait to outlive them to prove it wrong..

Re:Global Warming (1, Funny)

Anonymous Coward | more than 6 years ago | (#22569870)

The real problem as I see it is that Al Gore is going to expand to be so big that he engulfs the earth.

Suck on dicks, faghole mouth! (-1, Troll)

Anonymous Coward | more than 6 years ago | (#22570048)

Lard ass wants a cock?

Ah well... (2, Informative)

QJimbo (779370) | more than 6 years ago | (#22569422)

All good things...

Re:Ah well... (3, Funny)

kestasjk (933987) | more than 6 years ago | (#22569862)

If we do decide to revive the sun by sending a payload of quantum sparkles, I suggest not sending a religious nut-job who is obsessed with sunlight.

My 2c.

Re:Ah well... (1)

RuBLed (995686) | more than 6 years ago | (#22569940)

Yah, all good things.. especially Titan's tropical beaches.... (by that time)

I don't believe it. (1)

palegray.net (1195047) | more than 6 years ago | (#22569424)

I'm going to hold my breath to prove it. Check this thread in 100 years for an update.

Message from 100 Years into Future (3, Funny)

Anonymous Coward | more than 6 years ago | (#22569502)

Hmmm... a 7 digit user id... you must be old here.

Re:Message from 100 Years into Future (0)

Anonymous Coward | more than 6 years ago | (#22569858)

So are we, cowards till the end!.. Well this is one way I could hope for immortality...

Re:I don't believe it. (1)

ILuvRamen (1026668) | more than 6 years ago | (#22569922)

spoiler alert! We're gonna suck ourselves into an artificial black hole by then. Either that or break an atomic particle in half or something and create a super bomb that cracks Earth in half. Or maybe we'll accidentally teleport the planet someone with a wormhole. Or maybe we'll accidentally create two Earths in a quantum experiment accident and it will collide with the moon and bounce it into us. I mean come on, think about how high the odds are that in a couple million years (more like a couple hundred) someone will do something crazy or stupid and destroy the entire planet. A thousand years ago we were lucky we could crack a rock in half with technology. Now we can level a city. I don't wanna know what we'll do in the future but I'm sure we won't make it to supernova time.

Re:I don't believe it. (5, Funny)

icedcool (446975) | more than 6 years ago | (#22570004)

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.

Maybe (2, Funny)

QuantumG (50515) | more than 6 years ago | (#22569432)

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.

Last post (4, Funny)

Harmonious Botch (921977) | more than 6 years ago | (#22569436)

Heck, 7.6 billion years is ok by me; Chun the unavoidable will have been at my elbow by then.

Re:Last post (4, Funny)

SL Baur (19540) | more than 6 years ago | (#22570088)

Heck, 7.6 billion years is ok by me
I don't know. It'll probably happen a few months before Duke Nukem Forever is released. Dang, I was wishing I could play that game.

This is news? (5, Informative)

Cobalt Jacket (611660) | more than 6 years ago | (#22569438)

This is the way I was taught it would happen on astronomy shows from the 1980s. I don't get the big deal.

Re:This is news? (1)

palegray.net (1195047) | more than 6 years ago | (#22569470)

I just turned 27; my recollection of PBS science shows' take on this (specifically Nova [pbs.org] ) in the 80s was that we didn't know for sure (back then) which way things would go. Or my memory could be faulty, who knows...

Re:This is news? (1)

Nero Nimbus (1104415) | more than 6 years ago | (#22569486)

I was thinking more or less the same thing.

It must be a slow night.

Re:This is news? (5, Informative)

MillionthMonkey (240664) | more than 6 years ago | (#22569654)

They thought for a little while that the Earth might just make it, but now it's pretty clear to everybody that's not going to happen.

Re:This is news? (1)

justinmikehunt (872382) | more than 6 years ago | (#22569794)

And indeed that's what I learned in the 90s.

Re:This is news? (1)

Seumas (6865) | more than 6 years ago | (#22569834)

I remember reading an old set of Time Life books about the solar system from about 20 years ago that said said this, too. I didn't know there was any sort of debate over it. The only question I'd ever seen was whether it would be closer to six billion years form now or twelve billion years from now.

Anyway, it's not that big of a deal. If mankind hasn't gotten over religion and ignorance long before this is a concern and then moved on and out into the rest of the galaxy, then he deserves the same fate as his home planet.

Re:This is news? (1)

abshnasko (981657) | more than 6 years ago | (#22569846)

I remember learning about this in 4th grade. Editors, I think the key word in News for Nerds is "News"

quote time (0)

Anonymous Coward | more than 6 years ago | (#22569444)

Spaceballs?

Oh shit, there goes the planet!

Interesting Note (5, Funny)

bendodge (998616) | more than 6 years ago | (#22569458)

But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up.
(Wow! All my karma just went sailing past!)

Re:Interesting Note (4, Informative)

palegray.net (1195047) | more than 6 years ago | (#22569508)

I don't know why your karma would suffer from this... there are some interesting parallels between theories concerning the technological singularity [wikipedia.org] and the Biblical book of Revelation [wikipedia.org] (at least in some peoples' opinions). Why not add another metaphorical spin to things?

Re:Interesting Note (1)

maop (309499) | more than 6 years ago | (#22570090)

Why bring up crack pot theories?

Re:Interesting Note (2, Interesting)

benthurston27 (1220268) | more than 6 years ago | (#22570068)

"will come as a thief in the night" seems to suggest some element of surprise but several billion years of advance warning seems sufficient to not be surprised. But on another note is this what particularly morbid scientists do with their intellectual time or does it just seem that way to me?

Come on... (1)

The Ancients (626689) | more than 6 years ago | (#22569466)

As long as I've been alive, this has been pretty much the inevitable conclusion. Was there a turnaround in the cocaine infested 80s perhaps that we missed, or have since forgotten?

By the way, this is even in New Zealand, waaaaaaay down at the bottom of the globe (not far enough down that we'd be safe from this, however)

Uhhh, this isn't news (2, Insightful)

JimboFBX (1097277) | more than 6 years ago | (#22569478)

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.

Re:Uhhh, this isn't news (1)

Scotland Tom (974094) | more than 6 years ago | (#22569610)

Agreed. I've been seeing this exact projection on the Science and Discovery channels for years now. I wasn't even aware there was a competing theory.

Re:Uhhh, this isn't news (1, Funny)

Anonymous Coward | more than 6 years ago | (#22570022)

I think I have a "My First Picture Book of the Planets" that says the same thing.

Yes that old childhood science fav- from the publishers of "Garsh Ma, My DNA Made Me Do It!", "The Wondrous Tale of Mr. E. Coli (And Other Gastro-Intestinal Stories)," and "Heat Death! Why Nothing You Do Really Matters".

Shit. (5, Funny)

jerryasher (151512) | more than 6 years ago | (#22569480)

And to find this out the day I discover my paxil/zoloft/venlafaxine does nothing.

Beer me.

Armageddon (5, Interesting)

gummyb34r (899393) | more than 6 years ago | (#22569498)

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.

Re:Armageddon (2, Insightful)

Anonymous Coward | more than 6 years ago | (#22569686)

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.

It's certain that it will happen at least 9 times and 90% certain that it will happen 10 times? Or did you mean that there is a 99.9% probability or a .999 probability?

Re:Armageddon (-1, Flamebait)

Anonymous Coward | more than 6 years ago | (#22569994)

Fuck off dickhead.

Re:Armageddon (1)

ryanisflyboy (202507) | more than 6 years ago | (#22570086)

I would place my wager on this happening first...
http://www.endofworld.net/ [endofworld.net]

Didn't realise this was debated (1)

pembo13 (770295) | more than 6 years ago | (#22569516)

Discovery Channel, History Chanel and National Channel all show the same scenario of the sun expanding to and past earth.

Re:Didn't realise this was debated (1)

Atriqus (826899) | more than 6 years ago | (#22569620)

I was thrown off by this as well, considering I had astronomy books that stated this about at least a decade ago.

Re:Didn't realise this was debated (1)

jkro (1103265) | more than 6 years ago | (#22569920)

A good debate is like wine; the older the better.

Re:Didn't realise this was debated (1)

Architect_sasyr (938685) | more than 6 years ago | (#22570016)

Ok mildly off topic but astronomy was probably the only geek thing I never did (for shame, here's my punch-card and badge)

Will the gravitational pull get worse as the sun expands, will it stay the same or could we possibly be pushed (either artificially or by said sun) away from it. All these theories seem to hinge on Terra staying x miles away from point 0 at the centre of the big shiny light in the blue room. What's stopping us just moving the planet out of the way somehow (remember, in 7 billion years we're quite probably going to have the power to move planets anyway)... just curious is all...

Re:Didn't realise this was debated (1)

hardburn (141468) | more than 6 years ago | (#22569836)

And we all know how accurate those channels are.

I gave up on the whole lot years ago when I found that when they talked about stuff I already knew about, it was often completely wrong. Naturally, I then had to wonder about the accuracy of stuff I didn't know about.

This assumes we really know what powers the sun. (1)

arminw (717974) | more than 6 years ago | (#22569882)

The ancients assumed (believed) the sun is a giant camp fire. Then Einstein came along with his famous equation and humans built a hydrogen bomb. So then the solar campfire was upgraded to a thermonuclear fire. That's what we assume (believe) today.

Thermonuclear reactions produce lots of neutrinos. However, the number of those little particles we actually measure and how many we should be measuring if indeed the sun is a giant controlled fusion reactor, is way different. The number we measure is far too small. There are some rather convoluted explanations for this, but it really still is very much a puzzle why we don't measure more neutrinos.

It has been pretty well established, that heat moves from the hotter to the cooler region. If the interior of the sun is hot enough for fusion (about 20-25 million deg) it is conceivable that by the time the energy gets to the surface, the temperature could have cooled to the 6000 degrees we measure there. Now how is it then that as we move away from the surface of the sun, to its corona, the temperature we measure rises to 3 million degrees?

According to the way heat normally behaves, it should get steadily cooler as the distance from the sun increases. If fusion is truly the source of the sun's heat, then somehow, the laws of thermodynamics are turned on their head or for some unknown reason don't apply to this situation with the sun.

Maybe, we still don't REALLY know what powers the sun. Which of course makes the whole article pure speculation.

Seems easy enough. (5, Insightful)

jd (1658) | more than 6 years ago | (#22569542)

Accelerate Earth to put it into a wider orbit. This will solve Global Warming and the Earth being swallowed all in one.

Re:Seems easy enough. (0)

Anonymous Coward | more than 6 years ago | (#22569718)

of course you stole that idea from futurama.

Re:Seems easy enough. (4, Interesting)

AKAImBatman (238306) | more than 6 years ago | (#22569780)

Actually, jd is quite correct. Scientists have already been working out methods of moving the Earth should a climatic event threaten the livelihood of the human race. The Earth may be big, but there are no forces that prevent it from moving. Intentionally toss a few rocks past it, and the gravitational pull will slowly accelerate the Earth out of its current orbit.

Despite the fact that we only have 7.6 billion years to get the computations correct, I have a feeling that we'll be able to get it done right by then. (Either that or evacuate our Dyson Sphere. Whichever comes first.)

Re:Seems easy enough. (1)

jd (1658) | more than 6 years ago | (#22569968)

Just give me a long enough lever and a place to stand and I could move the Eath. Or a Greek philosopher/scientist, or something. Though moving an ancient Greek can be difficult at times.

Re:Seems easy enough. (0)

Anonymous Coward | more than 6 years ago | (#22570028)

If, in 7.6bn years, we have not figured out how to live on other worlds, then we're not worth saving and should get vaporized by the sun.

In actuality, the human race will have long since died out by that time anyway so we're worrying about something that will have nothing to do with us.

In fact, Earth will be a dead world billions of years before this happens. Nobody and no-thing will care when it finally gets incinerated.

Re:Seems easy enough. (1)

zippthorne (748122) | more than 6 years ago | (#22570094)

In actuality, the human race will have long since died out by that time anyway so we're worrying about something that will have nothing to do with us.


Why do you say that? Because of that y-chromosome repair fault thing?

Re:Seems easy enough. (1)

Divebus (860563) | more than 6 years ago | (#22570104)

How far would we have to move out in orbit to fix the leap year thing - as in add three more days every four years to the orbit? Or would we have to add a whole new month to get out of the way? And at what point do we start running into asteroids? Listen to me... "we"... heh.

Re:Seems easy enough. (1)

RuBLed (995686) | more than 6 years ago | (#22569804)

Let Chuck Norris fart in the sun's general direction.. That should do it..

Re:Seems easy enough. (0)

Anonymous Coward | more than 6 years ago | (#22569848)

NO!!! We don't want a supernova explosion to happen and the universe to be destroyed!

Re:Seems easy enough. (1)

dragonfire5287 (1213386) | more than 6 years ago | (#22569816)

Philip Jose Farmer had a book were humanity did just that, it is titled "Dark is the Sun."

Tell me (0, Redundant)

Dunbal (464142) | more than 6 years ago | (#22569566)

If this is such an earth-shattering discovery, how come I read about it in Carl Sagan's COSMOS 20-odd years ago?

slow news day?

The man was WAY ahead of his time. (1)

CFD339 (795926) | more than 6 years ago | (#22570034)

In fact, he was billions and billions of years ahead of his time. He was more ahead of his time than there are grains of sand on all the beaches on the earth....

Will this finally end... (1)

Nameisyoung007 (1009935) | more than 6 years ago | (#22569574)

the copyright for a Beatles song?

The Soundtrack of Our Lives (1)

xactuary (746078) | more than 6 years ago | (#22569576)

Jimmy Eat World.

OS Clock (1)

dohzer (867770) | more than 6 years ago | (#22569596)

I guess that means our operating system clocks only need to work up until the year 7.6 billion.
Someone work out how many bytes are needed to represent that time.

Re:OS Clock (2, Informative)

soundhack (179543) | more than 6 years ago | (#22569650)

32.823352272542484276756074858822 + 1 bits, so 5 bytes

Re:OS Clock (1)

childprey (1054198) | more than 6 years ago | (#22569942)

segmentation fault.

Re:OS Clock (1)

Whitemend (1192397) | more than 6 years ago | (#22569662)

7.6 billion years = 2.39832637 × 10^17 seconds I started it for you.

The Y7.6B Problem ...? (0)

Anonymous Coward | more than 6 years ago | (#22569622)

If we honestly can't figure out how to correct the orbit of the Earth some 7.6 Billion years from now, we deserve a painful death.

I think our odds are pretty good though.

Re:The Y7.6B Problem ...? (0)

Anonymous Coward | more than 6 years ago | (#22569682)

If we can figure out how to survive without leaving the Earth for 7.6 billion years I'm willing to say we will have had a good run!

Re:The Y7.6B Problem ...? (3, Interesting)

tubapro12 (896596) | more than 6 years ago | (#22569754)

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.

Read that in a Time-Life Science Book when I was 8 (1)

joebob2000 (840395) | more than 6 years ago | (#22569668)

So what's the news?

Forgot to say that was in the '70s (0, Redundant)

joebob2000 (840395) | more than 6 years ago | (#22569688)

and the books were first published in the late 60's

confusion re expanding to earth's orbit vs engulf (5, Informative)

Danny Rathjens (8471) | more than 6 years ago | (#22569672)

I was looking for something to mod up but all the replies so far are about how they learned the earth would be engulfed and surprised at the debate. I think the confusion is arises because there is no debate about whether the sun will expand to the size of earth's orbit. The debate is whether the earth will have moved far enough from that current orbit to not be engulfed. Here we go, wikipedia says precisely this:

While it is likely that the expansion of the outer layers of the Sun will reach the current position of Earth's orbit, recent research suggests that mass lost from the Sun earlier in its red giant phase will cause the Earth's orbit to move further out, preventing it from being engulfed.
http://en.wikipedia.org/w/index.php?title=Sun&oldid=193657154#Life_cycle [wikipedia.org]

And some of the academic references are actually a decade old: http://www.astronomy.ohio-state.edu/~pogge/Lectures/vistas97.html [ohio-state.edu]

Gravity Assist (1, Redundant)

EEPROMS (889169) | more than 6 years ago | (#22569680)

This disaster can actually be compensated for to some degree by moving earths orbit further out from the sun using gravity assist. What you do is capture a large mass be it a comet or a large asteroid then put it in elongated orbit around earth. As the large mass now circling nears earth it pulls on the planet thus moving it ever so slightly. Few billions year later and earth has moved far enough out to avoid annihilation for a few extra billions years.

Re:Gravity Assist (5, Funny)

Volante3192 (953645) | more than 6 years ago | (#22569720)

Or just build lots of robots and have them all vent out their exhaust pipes in the same direction at the same time.

Re:Gravity Assist (1)

The Evil Couch (621105) | more than 6 years ago | (#22570012)

That would cause the Earth's year to grow longer. We should create holidays on the new days, in honor of the helpful robots. We could name them Robonukah and Robanza.

Re:Gravity Assist (0)

Anonymous Coward | more than 6 years ago | (#22569908)

If we pull a comet or large asteroid into an elongated orbit, or indeed any orbit, around the Earth, then assuming we average our calculations over several billion years, the net acceleration enacted upon Earth by it shall equal exactly nil. It may pull more strongly at its perihelion, but this will be perfectly countered by the longer time that it will loiter near the aphelion of its orbit.

To put it more succinctly, I refer to the Law of Conservation of Momentum.

In any case, even if you were to try, you'd find you could not stabilise its orbit. The Sun-Eath-Moon gravitational interactions would soon expel it.

Posting as AC because I couldn't be bothered to create an account.

Wow talk about the slashdot community being slow.. (0, Redundant)

Allnighterking (74212) | more than 6 years ago | (#22569684)

I'm 51 years old and I first saw this story in the Weekly Reader in 1st grade..... ( *grin* )

Whew, there's still time (0)

Anonymous Coward | more than 6 years ago | (#22569712)

for the Year of the Linux Desktop to occur before the world ends. Better get a move on though.

By that time... (4, Insightful)

okmijnuhb (575581) | more than 6 years ago | (#22569738)

...humans will have destroyed it, and several others...

Well... (1)

TheNatealator (1246152) | more than 6 years ago | (#22569772)

Considering that only half of scientific papers are true (recent slashdot article I can't find anymore) and that astronomers also were off by a factor of 2 in one of the dimensions of our galaxy (slashdot again), I think this story has a long time to wait before it's newsworthy.

At some point (3, Funny)

michaelmalak (91262) | more than 6 years ago | (#22569774)

After 7.6 billion years, it's time to move out of mom's basement.

Close, but no (1)

JeanBaptiste (537955) | more than 6 years ago | (#22569776)

Actually a dying Earth will engulf the Sun.

By the time any of this happens, humanity will either have ascended or descended to a point where it won't matter anyways.

I, for one, cannot wait to be information and energy without having mass.

Re:Close, but no (1)

SeaFox (739806) | more than 6 years ago | (#22569990)

Actually a dying Earth will engulf the Sun.

That's only in the Special Edition version Lucas has planned.

In 7,6 Billion years.... (-1, Troll)

freedom_india (780002) | more than 6 years ago | (#22569778)

Wow! This is a slow news day.
Why can't we cover something that affects us 100 years from now? Or even that timeline is too short for us?

For instance how the president vetoes the Mortgage closure bill which allow judges to reduce interest rates and thus make homes affordable to pander to banks,
or how cheney continues to play the role of phantom-phase-shifting VP who is neither the executive nor the senate,
or iran oil bourse,
or even how to get money from virgin BA settlement?

One thing i can say: Even 7.6 billion years later, Earth would still consider Cheney as the worst president ANY country ever had, including Zimbabwe.
I have karma to burn.

No problem (3, Funny)

PPH (736903) | more than 6 years ago | (#22569788)

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!!

What? (1)

iminplaya (723125) | more than 6 years ago | (#22569806)

I read that stuff back in the 60's. And the sun's life expectancy was going to be around 9 billion years or so. Nobody was saying that the earth would escape.

Difficult to imagine... (1)

interactive_civilian (205158) | more than 6 years ago | (#22569808)

It will also expand, driven by helium fusion so that its outer layers reach past the earth's current orbit.
Out of shear boredom, I decided to do some calculations, using the following (someone please fix my math, if it's wrong):

Avg. distance from Earth to the Sun (according to Wikipedia [wikipedia.org] ) = 1.496x10^11 meters
Current mass of the sun (according to Google [google.com] ) = 1.9889x10^33 grams
Current Diameter of the sun (according to Google [google.com] ) = 1.4x10^9 meters
Volume of a sphere = (4/3)(r^3)
Density = mass/volume

Based on that:

Volume of the sun = 6.465x10^27 cubic meters
Density of the sun = 3.076x10^5 g/m^3 or about 300 kilograms per cubic meter

However, in the future:

Volume of red giant sun = 7.889x10^33 cubic meters
Density of red giant sun = 0.25 g/m^3 or about 250 milligrams per cubic meter

Can that be right? Can fusion happen at such a low density? For comparison, the average density of the earth's Atmosphere at sea level (of course depending on many factors) is about 1.225 kg/m^3.

Or, more likely, are my numbers off? Can someone check my math?

Regardless, the sizes and such involved are difficult to imagine, aren't they? A sphere with a current radius of about 0.005 AU will expand to a sphere with a radius of 1 AU? Huge. Mind boggling. My head asplode.

someone ate my pi (1)

interactive_civilian (205158) | more than 6 years ago | (#22569860)

Oops... Throw a "pi" up there into the Volume equation.

Re:Difficult to imagine... (1, Informative)

Anonymous Coward | more than 6 years ago | (#22569982)

IANAAP (Astrophysicist) and I don't know if your math is right, but your general thinking is probably on. You are essentially calculating an average density (not in tehnical terms, but in lay terms anyway). So the density on the edge will be really low because most of the mass will be near the center (just as the sun is today). So the fusion is going on in the dense part which, calculated along with the sparser outer layers, combines for an average density that seems too low for fusion. I would be interested to know whether your math is really that close though...anyone?

Re:Difficult to imagine... (4, Informative)

Einer2 (665985) | more than 6 years ago | (#22570020)

I doubt if this post is high enough to net any karma, but oh well. I'll chalk it up as my outreach for the day...week...year...something. The important quantity isn't the average density, but the core density (as fusion only happens near the core). As stars evolve off the main sequence, their outer layers may expand, but they also become much more centrally condensed.

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.

Well, there's only one solution here (0)

Anonymous Coward | more than 6 years ago | (#22569814)

We must destroy the sun right now! Our survival depends on it! I think if we point a giant firehose at it, we should be able to at least slow down Earth's demise. Why is this not on Obama, Hillary's and McCain's agenda? Fuckers.

Obligatory... (1)

that_itch_kid (1155313) | more than 6 years ago | (#22569826)

I, for one, welcome our new helium-filled, earth-devouring overlord!

I think I'm more interested in an estimate of (1)

Eternal Vigilance (573501) | more than 6 years ago | (#22569892)

how long the human race will survive. (no smiley)

While I have all my life shared the deep desire to know the "ultimate end" (if there even is such a thing), the more I pay attention the more I feel the cognitive resources spent on these kinds of calculations are almost shameful - the astrophysical equivalent of gunning down buffalo from the back of the train.

If we weren't trying to solve these problems I'd be the voice saying that we should. It was just that in a world of such instability, in reading this article I suddenly felt sad we were spending time figuring out what might happen in a few billion years, when so many of us desperately need to know simply how to survive tomorrow.

Wow, just writing that helps bring me back to balance (since my projective emotional response to something can only ever be a response to something inside me). Remembering my own personal priorities, with which I'd momentarily lost touch this evening, has me feel centered again. Thanks for giving me the opportunity to right myself...and for listening.

(P.S. My own thesis is that long before the 7.6E9 moment we'll have grown to be able experience ourselves as far more than we do now, not just as tiny elements at the effect of the cosmic turnings of the Sun and Earth, but at one with the entire Universe itself. And with that, time for bed...gotta survive tomorrow, too, you know. ;-) )

Can't wait that long (1)

daBass (56811) | more than 6 years ago | (#22569902)

In about 2 billion years the Milky Way could already collide with the Andromeda Galaxy [sciam.com] , which will more than likely change earth's cozy equilibrium that enables human life in a sub-optimal way.

Hey KDawson.... (1)

FlyingGuy (989135) | more than 6 years ago | (#22569928)

Uhmmm, next how about posting something that is actually news ok? I mean for fucks sake I learned this in grade school and that was over 35 years ago!/p

Re:Hey KDawson.... (0)

Anonymous Coward | more than 6 years ago | (#22570002)

Your [sic] old.

In other news (1)

eclectro (227083) | more than 6 years ago | (#22569960)

It has been reported from archeologists who have teleported from the future to our time that 7.59 billion years from now, Duke Nukem Forever is released to manufacturing.

On the bright side (1)

tumutbound (549414) | more than 6 years ago | (#22569974)

I'll be long dead by the time it happens, however it happens.

I wouldn't worry about it... (5, Informative)

AbsoluteXyro (1048620) | more than 6 years ago | (#22570030)

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.

It won't engulf me! (1)

TheSpengo (1148351) | more than 6 years ago | (#22570036)

7.6 billion years is way enough time to save up money to build my spaceship. I've started a spaceship fund, I will put $1 in it every year for 7.6 billion years! :D

Galaxy Collision (1)

TheAncientEvil (1247006) | more than 6 years ago | (#22570042)

Considering our galaxy should collide with the Andromeda Galaxy in about 3 billion years, I think it may be a moot point. Since there is a good chance the earth nor the sun may be still around, or may not be near each other of if passing gravity fields toss the planets out of their orbits, etc.

The Earth will be dead much sooner than that (2, Informative)

Detritus (11846) | more than 6 years ago | (#22570054)

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.

WTF.....? (2, Insightful)

IHC Navistar (967161) | more than 6 years ago | (#22570074)

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.

Phew... 7.6 billion.... (1)

feepness (543479) | more than 6 years ago | (#22570096)

I thought it said 7.6 million at first.
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