Assume the Sun magically blinks out of existence and the Earth leaves the solar system. What’s the closest start it could reach, assuming it leaves the solar system on a tangent to it’s current orbit. And when it arrives, would any signs of life be recognizable? Would it be a frozen time capsule or would everything be gone?
Earth is orbiting the sun at about 66,700 MPH, so that’s the linear speed you’d have after deleting the sun. For comparison, the Voyager space probes are currently trundling along at around 35,000 MPH.
Alpha Centauri is about 4 light-years away. If you were headed in that direction, you’d get there in about 40,000 years. You’ll have to define what you mean by “signs of life;” we’d freeze up in fairly short order, but there’d be plenty of evidence of things that once lived. We’ve recovered DNA from long-extinct mastodons, for example.
Problem is that Alpha Centauri doesn’t lie in earth’s orbital plane, so we wouldn’t head in that direction when the sun got deleted.
So next question: what’s the nearest star that lies in earth’s orbital plane?
Depends on how much tolerance you’re allowing for “in” the plane. If you’re hoping for us to pass within a few AU of the target star, forget about it: You’d probably pass clear out of the Galaxy before that happened.
Unless you’re in a science fiction story. Then the odds are 100% that the Earth would intersect a star system with intelligent life.
For shits and giggles I deleted the sun in the gravity sim Universe Sandbox and ‘aimed’ Earth at Jupiter to see if it would have an effect, but Earth’s speed was unhampered even by the Jovian gravity well. Results elsewhere were pretty predictable, all the inner planets flew off instantly.
For fun, I used the astronomical data available in Mathematica to run the numbers on this question. Basically, I calculated the distance on the sky between each of the 88k stars in the Wolfram database and the ecliptic, and then multiplied it by the distance to the star in question to get an estimate of how far we would pass. If I did it right, our best bet is to aim for 29 Arietis, which is about 0.016° off of the ecliptic and about 98 light-years away. We’d only miss it by about 1730 AU. The next best options would be Van Maanen’s Star (0.11° from ecliptic, 14 ly away, miss by 1800 AU) and HD 46466 (0.00038° from ecliptic, 4660 ly away, miss by 1970 AU.)
Of course, the proper motion of the stars would mean that by the time we got to the spot where the star had been when we were “launched”, it would no longer be there. Still, this was a fun exercise for a lunch hour.
29 Arietis has a couple of other things going for it, too: As a multiple system, it might be able to capture us, and it’s got a component that’s a bit brighter than the Sun (the vast majority of stars are red dwarfs).
Awesome! Thanks. So if things worked out perfectly, Earth could theoretically reach another star and still have lots of evidence of life.
Not just evidence. It would probably have life. According to a video linked from a similar-themed thread here, while the surface of the oceans would freeze, the planet’s core heat (mostly from nuclear fission) would continue to heat the planet and keep parts of the ocean liquid, especially around fumaroles, where we already have biota that doesn’t depend on the sun for energy.
It’s quite likely that those biota would do just fine as we cruised through space, with the surface a dark wasteland with only the frozen ghosts of its ancient fecundity.
With no sun, wouldn’t the atmosphere freeze and blanket the earth with a thick layer of frozen nitrogen at the top, and a thinner layer of oxygen beneath (being about 78% nitrogen, 21% oxygen and 1% other)?
If so, anyone wanna work up the numbers of how many feet each layer of frozen atmosphere would work out to?
That was the premise of one of the first science fiction stories I ever read,A Pail of Air by Fritz Leiber.
As Leiber’s story suggests, humans might even be able to carry on using geothermal and nuclear power to survive.
I look at it this way. Four billion years from now, the Andromeda Galaxy will collide with the Milky Way. In spite of the billions of stars in each galaxy, they are so far apart compared to their sizes, it’s very unlikely that any will collide. So it will be much less likely that our tiny renegade Earth will get caught by another star. For all practical purposes, we’ll be roaming forever.
Each square inch of the earth’s surface has 14.7 pounds of air above it, comprised of 2.94 pounds of oxygen and 11.76 pounds of nitrogen.
Density of liquid nitrogen, 0.02919 pounds per cubic inch
Density of liquid oxygen, 0.0516 pounds per cubic inch
For this discussion, I’ll assume the density of solid O2 and N2 are the same as their respective liquid forms.
So a column of frozen oxygen weighing 2.94 pounds would be 57 inches high, and a column of frozen nitrogen weighing 11.76 pounds would be 403 inches high. Basically, everywhere on the earth would be covered by a 38-foot thick layer of frozen atmosphere.
This assumes that it’s a solid layer, i.e. ice rather than snow. If we end up with a rain of liquid which then freezes solid, then 38 feet is indeed what we’d get. If it precipitates as snow, it would be considerably fluffier. Water-snow has a density that is 5-15% that of ice; if the same ratio held true for O2/N2-snow, then the coating could be 250-760 feet thick.
I’d guess there wouldn’t be much blowing and drifting, since the sun is no longer supplying the power necessary to make weather happen (and the atmosphere gets thinner and thinner as more of it solidifies). So it should be a nice, even layer across every square inch of the earth’s surface.
I remember reading that there wouldn’t even be any near misses, most likely. A “near miss” was where the gravity of a passing star was greater than the sum of the gravitation from all the rest of the stars, or something like that.
Thanks for doing the math. Nitpick: since water is polar but O2 and N2 aren’t, my guess is that O2 and N2 “snow” wouldn’t be nearly as fluffy as H2O snow. But since I’ve never seen O2 or N2 crystals, it’s just a guess!
Here you go. Solid nitrogen.
Not that you can see any crystal structure or anything. But the idea is nice.
Well, either that, or the divorced professor, his ex-wife and his 24-year old supermodel PhD assistant will team up to prevent the sun from disappearing at the last minute, right after they have to convince the military not to nuke something first.
I don’t know that it’d be fluffy at all. Real snow traps air pockets. If the air itself is the thing freezing, there’s nothing left to “fluff up” the precipitate. Earth’s gravity would cause it to crunch down, like a boot on snow. The only thing holding its volume up would be its crystal structure, which I don’t think contributes to a snow bank as much as the air does.
You wouldn’t get air pockets, but there’s no reason you couldn’t get vacuum pockets.
You don’t want to go there. It’s a white dwarf. Not the kind of place you want to raise your kids in.
Van Maanen’s Star is quite close as stars go, but it also has a high proper motion. It’s some 5 degrees north of the equator, and is moving south at 2.7 arcsec/year. By my BOTEC, it should be right on the equator in 7200 years. However, as noted above, it would take the Earth 44,000 years just to go the distance to Alpha C, which is only about a third of the way to van Maanen’s. So it’s going to miss by quite a ways.
Gosh, I hope it doesn’t happen.