# Grapefruit-sized sun
**URL:** https://boards.straightdope.com/t/grapefruit-sized-sun/490150
**Category:** Cecil's Columns/Staff Reports
**Created:** [March 20, 2009, 1:08pm UTC](https://boards.straightdope.com/t/grapefruit-sized-sun/490150 "2009-03-20T13:08:00Z")
**Posts on this page:** 4
**Page:** 2
### Author:  [@davekhps](https://boards.straightdope.com/u/davekhps)
#### Post date: [March 27, 2009, 7:39pm UTC](https://boards.straightdope.com/t/grapefruit-sized-sun/490150/21 "2009-03-27T19:39:16Z")
> [@oogabooga](#):
>
> familiar enough with to do for you, it gets hard to say, here. One thing is for sure - it would completely wreck Earths current orbit, which would eventually result in it’s demise.
Let’s be specific-- that’s only if our grapefruit-sun was here on Earth, or in another place in our Solar System.
Replace the Sun with a black hole of the same mass and the gravity is the same-- we wouldn’t notice a difference (well, gravitationally, at least-- it would, however, get a tad. . . _chilly_).
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### Author:  [@aerodave](https://boards.straightdope.com/u/aerodave)
#### Post date: [March 27, 2009, 8:31pm UTC](https://boards.straightdope.com/t/grapefruit-sized-sun/490150/22 "2009-03-27T20:31:58Z")
> [@ZenBeam](#):
>
> Anyway, the contribution due to a grapefruit sized volume of the Sun fusioning is completely negligible. The Sun has about 1.4 10[sup]30[/sup] time the volume of a grapefruit, and [radiates 3.8 10[sup]26[/sup] Watts](http://en.wikipedia.org/wiki/Sun), so an average grapefruit sized volume generates less than a milliwatt.
But that energy doesn’t come from the entire volume of the sun. There’s only a limited volume at the core where the density is high enough for fusion to take place. I don’t konw how big a sphere that is, but that’s the region of which you’d have to consider a grapefruit-sized piece.
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### Author:  [@Damp](https://boards.straightdope.com/u/Damp)
#### Post date: [March 27, 2009, 8:49pm UTC](https://boards.straightdope.com/t/grapefruit-sized-sun/490150/23 "2009-03-27T20:49:04Z")
So, being that it’s hypothetical there is several different situations you can set up, considering the original question was rather unspecific…
the sun, being a star is massive enough for nuclear fusion, which meaning it would easily consume the planet either in a fiery implosion or explosion.
the new sun, being the size of a grapefruit is of the same composition as the sun, so you have a superheated mass of hydrogen and helium, this is i believe what most people have described… which would be a far more local destruction.
or being hypothetical the new sun acts in and on itself as if it were in a seperate universe of smaller proportions and acts on other things in the same way as the natural sun does just to a far lesser extent probably proportionate to volume, which zenbeam did the math on… finding it producing less than a milliwatt. So it wouldnt even produce enough light to be observed?
So in summary
Boom!
Bang!
Dud.
So all boring in a long term observable perspective, gee I guess it IS the right size.
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### Author:  [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)
#### Post date: [March 27, 2009, 9:08pm UTC](https://boards.straightdope.com/t/grapefruit-sized-sun/490150/24 "2009-03-27T21:08:13Z")
> [@aerodave](#):
>
> But that energy doesn’t come from the entire volume of the sun. There’s only a limited volume at the core where the density is high enough for fusion to take place. I don’t konw how big a sphere that is, but that’s the region of which you’d have to consider a grapefruit-sized piece.
From the link (see the **Core** section), the core is considered to be the portion out to 0.2 times the solar radius, and produces 0.3 W / m^3.
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