I had a bet with my friend about how long it would take for the Pacific Ocean to boil away if you put the Sun into it. He said a week but I told him that’s too short of a time period because the Pacific Ocean is really big, so I said three weeks. Which one of us is correct?
What do you mean by “into it”? The Pacific Ocean is a very thin layer of water at the surface of the Earth, about 10.9 km deep at the deepest spot. The Sun is 1,390,000 km in diameter.
Like, if you dropped the Sun into the Pacific Ocean.
You have a real problem with scale.
I think more technically you’d drop the earth into the sun.
And all the oceans would evaporate long before impact.
it would be instantly vaporized/destroyed
It would evaporate before the sun got anywhere near it and the water molecules would be ripped apart well before it touched the ocean
Can I ask, just how big do you think the sun is in relation to the earth?
Do you think it is smaller than the earth? Do you think its smaller than the Pacific Ocean?
Your question is backwards. The sun is many many many many many times larger than the Earth. You can’t drop it into the Pacific Ocean, rather you would drop the Earth onto the sun. The Pacific Ocean in those cases would be gone in milliseconds, and the Earth not much further behind.
You’re asking something like “If I put this entire forest fire into this drop of water, how long would it take to boil the water?”
Oh come on - we all know that the moon is bigger than the sun. How else could it cover the sun in an eclipse.
“You see, the sun is what astronomers call ‘very, very large’…So large, it could not possibly be fit into the Pacific Ocean.”
Just remember, our purpose here is to fight ignorance, not ridicule it. (He says, stifling a grin.)
But yeah, the sun is really big. I mean, really big, even though it’s small to middlin’ compared with other stars. But really big compared to the Earth.
Imagine the thing on the bottom left being placed “in” the very thin later of water on the thing on the upper right. (Also: here’s a rendering of the Earth without water to give you a sense of the thinness of the oceans.)
To give you another idea, this is a neat graphic that shows just how much water is actually on Earth.
http://ga.water.usgs.gov/edu/2010/gallery/global-water-volume.html
It’s been my desktop wallpaper for awhile.
To try to get closer to what the OP is envisioning what would happen if you submerged a sun temperature box in the ocean? If the box is only the temperature of the surface of the sun you’d get a lot of local boiling and steam. The steam would condense and then fall back into the ocean as rain. The ocean as a whole would be unaffected and would never boil off and evaporate.
In any case, if the Earth was dropped into the sun, it would disintegrate in the blink of an eye. The oceans would do more than merely boil. The sun isn’t fire, it’s “plasma”, which is what matter turns into when it’s so hot that there aren’t any molecules at all (so, no water). There aren’t really even atoms as we normally think of them, since the electrons are all free from the nuclei.
So, not only is the sun really big, it’s also really hot. Hotter than anything here on Earth other than a nuclear bomb, and some very tiny spots in some (really huge) physics experiments.
Are you asking about the power output of the sun in comparison to the heat capacity of the Pacific Ocean, if we allow it to turn to steam? We can calculate that, if we disregard the logistical problems of physical scale, and just imagine that somehow all of the power output of the sun is dumped into the Pacific ocean until it’s turned to steam.
Pacific ocean is estimated to be 660M cubic km.
The power output of the sun is 3.9 x 10[sup]26[/sup] W.
Heat of vaporization of water is 2260 kJ/kg, or 2,260,000 kJ/m[sup]3[/sup].
Disregarding the energy required to raise the temperature of the Pacific ocean to 212F, the total time to boil it would be:
t=V*dH/P
t = 660M km[sup]3[/sup] * (1000m/km)[sup]3[/sup] * 2,260,000,000 J/m[sup]3[/sup] / 3.9 x 10[sup]26[/sup] W
t = 3.825 seconds.
That’s a remarkably human-time-scale number, considering the huge numbers involved. I would have guessed a very large or very small amount of time, but there it is.
[sub]Someone check my math…[/sub]
Is that a reasonable thing to do? How does the energy requirted to raise the water from, say, 50F (a rough guess for the average temperature of the ocean) to 212F compare with the energy required to actually vaporise it?
Yeah, the folks saying that the earth would vaporize instantly are wrong.
What you need to do is to calculate how much energy is being emitted from an area of the Sun the size of the Pacific ocean. It’s going to be surprisingly small. The Sun emits a lot of energy as a whole, but the surface energy density isn’t that big (the Sun has a LOT of surface area).
In the interests of realism (obviously a big concern with this question), we should probably use the electromagnetic luminosity rather than the total luminosity. Neutrinos aren’t going to impart much of their energy to the water; they’ll just pass right through it. So the solar luminosity should be 3.839 x 10[sup]26[/sup] watts rather than the 3.9 x 10[sup]26[/sup] watts figure you used. It makes a minuscule difference to the final answer, though.
It takes about 4.2 kJ to raise one kg of water by 1°C. So to raise the temperature by 90°C (which is what you’re proposing) would require 378 kJ, or about one-sixth of the energy required to boil it away. By my calculations, this would bring the total time for the process up to about 4.5 seconds.
Sometimes the numbers just work out right. There are about as many molecules in a thimbleful of water as there are thimblefuls of water in the Earth’s oceans; it just happens that human scale is right in the middle between the molecular scale and the oceanic scale. This seems like a similar situation to me.
I get 1.9 days, by scaling MikeS’s result by the ratio of the surface areas of the Sun vs Pacific Ocean.