Earth's Fate

[nag622]

When the sun expands into its Red Giant stage, I understand that its gravitational field will weaken. If this is true, is it possible that the earth may escape being consumed by the sun as mercury and venus would? <br /><br />My research has indicated that the sun may expand as far as the earth's orbit. I haven't located anything which indicates that it would expand outside of that, thereby consuming the earth as well.

 

[lucas_900]

From Wikipedia:<br />"It [the sun] will become sufficiently large to engulf the current orbits of the solar system's inner planets, including Earth. However, the gravitational pull of the sun will have weakened by then due to its loss of mass, and it is possible (but unlikely) that Earth may escape to a wider orbit."<br /><br />Regardless, the earth will be a lifeless lump floating about in space. Life will not survive the intense heat, and the radiation wouldn't do much good either. The mountains will melt and the earth's oceans and atmosphere will evaporate. The earth will then be a lifeless rock, however, that is about 4-5 billion years away, so I doubt it will affect us.

 

[nexium]

What will happen when, and if, our Sun becomes a red giant may be a surprise. Astronomers mostly think that simular stars have similar destinies. Are we sure the red giant stars we observe were once class G stars similar to our Sun? I don't think we have watched even one star make the transition from G to red giant.<br />We have observed red giant stars expelling large amounts of mass. But is that a total mass loss of 1% or 10%. If 10%, the planets would, I think, move perhaps a million miles farther from the Sun due to the solar wind and the reduced mass (thus gravity) of the Star. For Earth, a million miles is only a bit over 1% farther from the Sun. At best Earth will lose part of it's volitiles, and only the poles will be cool enough for biological beings to survive, unless our sun has a weak red giant stage, or is refuled, by multiple Jupiter size and larger impactors.<br />Even if we have viewed a Jupiter size mass striking a class G star, we can only guess that was the cause of the sudden brightness change. The next generation of great telescopes has a slight chance of observing such a collision. Neil

 

[heatherjk]

After the Hydrogen burning phase, the sun's core will collapse until it's internal temperatures are great enough to fuse Helium, meanwhile shedding it's exterior to distances of ~100 times the radius today. When the Helium flash occurs the sun will become 1000 times more luminous than it is today, causing the earth's temp. to rise to about 1000k! It will then maintain equillibrium (pressure/gravity) for ~100 million years. After the Helium is exhausted the sun will expand again in its last million years, once again increasing its luminosity by the thousands. The edge 'might' reach the Earth's surface. But, in response to your question.....It will finaly eject it's outer layers becoming a planetary nebulae that will extend past Pluto and eventually mixing with the ISM. Left over, if it hasn't been destroyed, will be a cold and crispy little rock, formerlly known as Earth, and our new sun, a white dwarf.

 

[newtonian]

Neil - Good post. Crazyeddie is posting on the more popular, and fatalistic, model<br /><br />Indeed, solar loss of mass may indeed allow earth to escape - and to what extent varies according to which model you accept as a closer approximation to what will really happen.<br /><br />All of this also leaves our Creator out of the picture - as if all will proceed without intelligent interference - you can contrast the prophecy in Revelation 21:3 -5 which has earth made new, death having been eliminated, and the tent of God being with mankind. <br /><br />What the tent of God might be is not stated - it may simply mean God will protect earth.<br /><br />However, I do find it stretching coincidence that earth's crust has an unusual abundance of the necessary elements to protect us during red giant phase - notably aluminum and silicon and oxygen (e.g. pure silica glass, silica is SiO2).<br /><br />It is certainly wise to be humble about assertions concerning earth's and sun's future - as you note, stars differ greatly in many complex properties - it is not simply hydrogen fusion - e.g. it involves the degree of mixing of core to surface solar layers which in turn involves floating magnetic fields and dynamoes which involve ions in motion which would naturally cause some mixing. <br /><br />A stirring time of 5 billion years for our sun would be difficult to detect but would throw estimates for red giant phase way off.<br /><br />Some dogmatically assert zero mixing - but the proof is lacking for this assertion.<br /><br />Crazyeddie's answer to you concerning refueling of our sun by impactors assumes specifice properties on impact.<br /><br />See the Scientific American article on When Star's collide - specifically the possible rejuvenation of main sequence stars by collision with brown dwarfs, etc.<br /><br />The exact properties after such a merger would depend on the timing (say 3-7 billion years from now), the mass and composition of the brown dwarf, the trajectory (angle) of impact,

 

[vogon13]

Earth's fate?<br /><br />Earth's fate!<br /><br />Bwa, ha, ha, ha, ha!!<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[CalliArcale]

As a brief theological sidebar, I don't think God will shield the Earth when the Sun turns to a red giant. I think we're expected to vacate it before then. The first commandment Man was given, according to Genesis, was to go forth, be fruitful, and multiply. I think that's how we're meant to survive the end of the Earth; by colonizing other worlds. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[mooware]

<font color="yellow">Crazyeddie is posting on the more popular, and fatalistic, model </font><br /><br />And for good reason. It's a scientifically valid model.<br /><br />Our best hope for survival would be to evacuate this rock before temps start to rise. Which will be long before the sun expands. To sit here and wait for the supernatural to intervene and save us all, will ensure our extinction.<br /><br />

 

[newtonian]

Calli - Interesting theological sidebar!<br /><br />Now, why do you think that?<br /><br />I will await your response before responding better - as I cannot do a reasonable analysis without knowing the basis for your conclusions.<br /><br />However, please note these Biblical verses on earth's future:<br /><br />(Isaiah 45:18) 18 For this is what Jehovah has said, the Creator of the heavens, He the [true] God, the Former of the earth and the Maker of it, He the One who firmly established it, who did not create it simply for nothing, who formed it even to be inhabited:. . .<br /><br />(Psalm 37:29) . . .The righteous themselves will possess the earth, And they will reside forever upon it. . .<br /><br />(Revelation 21:3-5) 3 With that I heard a loud voice from the throne say: “Look! The tent of God is with mankind, and he will reside with them, and they will be his peoples. And God himself will be with them. 4 And he will wipe out every tear from their eyes, and death will be no more, neither will mourning nor outcry nor pain be anymore. The former things have passed away.” 5 And the One seated on the throne said: “Look! I am making all things new.” Also, he says: “Write, because these words are faithful and true.” <br /><br />(Hebrews 1:10-12) . . .And: “You at [the] beginning, O Lord, laid the foundations of the earth itself, and the heavens are [the] works of your hands. 11 They themselves will perish, but you yourself are to remain continually; and just like an outer garment they will all grow old, 12 and you will wrap them up just as a cloak, as an outer garment; and they will be changed, but you are the same, and your years will never run out.”<br /><br />[Note: as these verses do not contradict, perish means extreme change comparable to destruction - evidently survivable - the tent of God will be with mankind.]<br /><br />(Psalm 115:16) . . .As regards the heavens, to Jehovah the heavens belong, But the earth he has given to the sons of men.<br /><br />[Note: thus earth is unique

 

[newtonian]

mooware - Apparently you have not read my surviving red giant phase thread.<br /><br />Otherwise you would not have falsely accused me of promoting a sit and wait attitude.<br /><br />That is far from the truth!<br /><br />It saddens me that you wish to abandon earth - which is so lovingly fine tuned for human life! No other planet within reach comes close to earth for happy human habitat, not to mention habitat for the many varied beautiful life forms on earth.<br /><br />I know many do not care about this earth - this is one reason man is destroying the earth.<br /><br />I am an environmentalist, and an organic gardener - as is my wife.<br /><br />We do not burn on our property - we compost.<br /><br />Burning contributes to global warming by increasing atmospheric CO2. Composting locks carbon in soil which also helps counteract the loss of earth's top soil.<br /><br />It is sad so many choose to deplete earth's soil, add to atmospheric CO2, destroy biodiversity and forests, destroy habitats for the many varied and awesome life forms.<br /><br />It is no wonder the Bible foretells in Revelation 11:18 that our Creator will bring to ruin those ruining the earth.<br /><br />I hope some will listen to me - and many scientists also - and stop destroying our still beautiful but suffering ecological environment.<br /><br />This is not a matter of fate.<br /><br />It is a matter of choice.<br /><br />Abandon earth and go to other planets?<br /><br />Preserve and beautify earth and explore other planets is, I believe, a much wiser choice - whether you believe in God or not.

 

[mooware]

<font color="yellow">It saddens me that you wish to abandon earth </font><br /><br />It would be a matter of survival. The Earth will eventually die, as all things do. Should we die with it?<br /><br /><font color="yellow"><br />I know many do not care about this earth - this is one reason man is destroying the earth. </font><br /><br />Don't equate. "abandoning" the Earth with uncaring willfulness to destroy it. We should absolutley take care of our rock. But again, the Earth will eventually die. I don't believe the species should die with it.<br /><br /> <br /><br /><br /><br /><font color="yellow">Preserve and beautify earth and explore other planets is, I believe, a much wiser choice</font><br /><br />Well, you're ancestors can stay behind be incincerated if they so choose. Hopefully, mine will choose survival.<br /><br />In any event, we'll be long gone.<br /><br />

 

[newtonian]

mooware - Are you tired? You posted:<br /><br />to my statement:<br />Preserve and beautify earth and explore other planets is, I believe, a much wiser choice <br /><br />You respond:<br />Well, you're ancestors can stay behind be incincerated if they so choose. Hopefully, mine will choose survival. - In any event, we'll be long gone. <br /><br />My response - I doubt my ancestors were incinerated - cremation has not been historically popular. My ancestors are German-Irish, btw.<br /><br />They are indeed long gone.<br /><br />However, I prefer to think positive - to work for, and hope for, survival on our beautiful planet - rather than adopt a fatalistic attitude.<br /><br />Sadly, many species are indeed dying on our planet - but this is due to those who fail to care.<br /><br />We encourage caring for our beautiful planet.<br /><br />For example, see the following links concerning saving our environment:<br /><br />http://www.watchtower.org/library/g/2003/11/22a/article_02.htm<br /><br />That is just a sampling of how we are alerting the public to the problems man is causing and the possilbe solutions for survival.<br /><br />How the earth will be saved:<br /><br />http://www.watchtower.org/library/g/2003/11/22a/article_03.htm<br /><br />Endangered species, why be concerned:<br /><br />http://www.watchtower.org/library/g/1996/8/8/endangered_the_scope.htm<br /><br />Why species are in danger - e.g. habitat destruction:<br /><br />http://www.watchtower.org/library/g/1996/8/8/why_species_are_in_danger.htm<br /><br />Conservation vs. extinction, e.g. human intervention:<br /><br />http://www.watchtower</safety_wrapper

 

[nexium]

Hi crazyeddie: Unless peer pressure is awful among professional astronomers, my guess is each astronomer has a different model, some radically different, but they may concider it prudent to stay close to mainstream when teaching in the class room. I do agree however that we should persue all practical means of diversifing our habitation off the Earth's surface as there are likely many other potential disasters before solar radiance cooks us. Neil

 

[mooware]

<font color="yellow"><br /><br />Are you tired? You posted: <br /></font><br /><br />I meant your decedents.<br /><br />In any event, failing to care for the planet will not help it much when the sun goes red giant. And I'm not advocating that we trash the planet in the mean time.<br /><br />

 

[doubletruncation]

If you're interested, you can see for yourself a model of what the sun will look like over time, but it will require a little bit of math to understand it. Goto to the web-site<br />http://www.te.astro.it/BASTI/WEB_TOOLS/IM_HTML/index.html<br />then select "Interpolated Track" for output type, and "Z = 0.0198 Y = 0.273" for chemical composition, and hit submit. Specify "1.0" for the mass of the object and you will get a nice data-table showing you the age (in logarithm base ten of years), Mass as a fraction of the mass of the sun (Note that it assumes that the star starts at 1 solar mass and loses mass over time, so the mass listed is always a little less than the mass of the sun, but it's good enough), the logarithm of the luminosity over the current luminosity of the sun, the logarithm of the effective temperature (in kelvin), and a whole bunch of other numbers giving magnitudes/colors that you might measure using different filters.<br /><br />So what does the Sun look like now? The age of the solar system is ~4.5 billion years, so that would be log(4.5*10^9) = 9.657. Scroll to that, and you see that the third column is nearly zero, meaning log(L/Lsun) = 0 so L/Lsun = 1. It's not exactly zero, so perhaps this model is not perfect, but it's good enough for our purposes. To get the radius of the sun you can use the black body law, L = constant * R^2 * T^4, so log(R/Rsun) = 0.5*log(L/Lsun) - 2.0*log(T/Tsun). The table gives temperature in log(T/kelvin), the effective temperature of the sun is 5778 K, so you get the radius from table using:<br />log(R/Rsun) = 0.5*log(L/Lsun) - 2.0*(log(T/kelvin) - 3.762)<br /><br />Alright, so now for the fun part, as you scroll down (into the projected future for our sun) you'll see that the second column (the mass) gets smaller, the third column (the luminosity) gets larger, and the fourth column (the effective temperature) gets smaller. In this model, <div class="Discussion_UserSignature"> </div>