The Astronomy Thread

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Captain Suave

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I remember reading somewhere that the inner core of the sun, where the pressure and temperature is high enough for the fusion to take place, only produce something like 300 w per cubic meter.

It's not an issue with the concept of fusion, just the particulars of the stars. Fusion in other contexts is vastly more intense.


"The power output of the core of the Sun is about 276.5 watts per cubic metre — that's almost three of the old 100W light bulbs. On a power/volume basis, it's a lot less than your body emits (about 100 W) and around the same as a compost pile.


How can it be so low? After all, a relatively small hydrogen bomb such as the American W88 has the explosive power of just under half-a-million tonnes of TNT — and fits into a volume smaller than a rollaway wheelie bin. So, if the Sun does nuclear burning, how come it generates less power (volume for volume) than a hydrogen bomb?


The answer is surprising. The Sun does do nuclear burning of hydrogen atoms, but only very occasionally. How occasionally? On average, any given hydrogen atom will run into another hydrogen atom only once every five billion years. The Sun's core does do nuclear burning, but very sparsely, with the reactions few and far between. Luckily, the core of the Sun is enormous, so even though it's only as powerful as a compost pile, there's enough energy given off to keep our planet warm."
 
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Mudcrush Durtfeet

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I'm not really up to date with fusion and fission, but isn't fusion not that effective ? I remember reading somewhere that the inner core of the sun, where the pressure and temperature is high enough for the fusion to take place, only produce something like 300 w per cubic meter.
Or we are using something else ?
Hypothetically fusion could be a better power source than fission, but we're many years from accomplishing this, if we ever do.
 
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BrutulTM

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Sun is enormous, so even though it's only as powerful as a compost pile, there's enough energy given off to keep our planet warm.

So clearly we need to start launching all of our shit into outer space so by the time the sun burns out we will have a big enough shit ball keep earth warm.

shooting star GIF
 
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Oldbased

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So clearly we need to start launching all of our shit into outer space so by the time the sun burns out we will have a big enough shit ball keep earth warm.

shooting star GIF
Dude, we only have less then 10 years before Earth self incinerates according to the science.
 
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Cybsled

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I'm not really up to date with fusion and fission, but isn't fusion not that effective ? I remember reading somewhere that the inner core of the sun, where the pressure and temperature is high enough for the fusion to take place, only produce something like 300 w per cubic meter.
Or we are using something else ?

It’s a technical hurdle at the moment to create fusion power generation that produces more than it consumes on a usable scale. The US and Europe have made good progress, but we are many decades out from something potentially game changing for civilization
 
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LachiusTZ

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We don't have the materials science right now to do it, I think.


I haven't watched this one since it came out, but I don't recall any real barriers outside of manufacturing processes etc.

If you don't watch his content, you should, given how much you participate in this thread.

I haven't come across many, if any instances of him just getting the raw math or science wrong...
 

Captain Suave

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I don't recall any real barriers outside of manufacturing processes etc.

Space elevators are "possible" with carbon nanotubes; we just aren't anywhere close to being able to produce them in the necessary length/quality.
 
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LachiusTZ

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I don't think the ring requires that...

Are you sure space elevators do?

Been a long time since I've watched either video tho.

C Captain Suave are you referring to solely passively supported structures?

Or the active support that he talks about?
 

Captain Suave

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I didn't watch the video; I assumed you were talking about elevators since that's what Mudcrush was discussing in the post you replied to.

For the standard version of a space elevator with one end anchored on Earth, you need materials with an extremely high tensile strength-to-weight ratio. Last time I read about it, the only likely candidate was carbon nanotube cable, which should be possible but we haven't figured out how to produce.

There are some alternative design concepts that work with today's materials, but they would still require traditional methods to get off Earth:

 

LachiusTZ

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I didn't watch the video; I assumed you were talking about elevators since that's what Mudcrush was discussing in the post you replied to.

For the standard version of a space elevator with one end anchored on Earth, you need materials with an extremely high tensile strength-to-weight ratio. Last time I read about it, the only likely candidate was carbon nanotube cable, which should be possible but we haven't figured out how to produce.

There are some alternative design concepts that work with today's materials, but they would still require traditional methods to get off Earth:


Jfc, my bad. Was busy making fun of stupid and did a stupid of my own.

I want to say it's feasible, but I can't remember if that was with or without nano tubes etc.


Like I said, the guy nails pretty much everything and I've never seen a credible counter to his math or science
 

LachiusTZ

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LachiusTZ

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Watched the whole thing, and it was the wrong episode. Lol

looks like


And the subsequent one are where he details active support
 
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meStevo

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This is pretty neat.

'For the first time, astronomers have captured solid evidence of a rare double cosmic cannibalism — a star swallowing a compact object such as a black hole or neutron star. In turn, that object gobbled the star’s core, causing it to explode and leave behind only a black hole.'

 
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Edaw

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'For the first time, astronomers have captured solid evidence of a rare double cosmic cannibalism — a star swallowing a compact object such as a black hole or neutron star. In turn, that object gobbled the star’s core, causing it to explode and leave behind only a black hole.'

bbwh.jpg