# The Naked Scientists Forum

### Author Topic: How long would it take for a black hole on Earth to swallow the Sun?  (Read 8885 times)

#### LeeE

• Neilep Level Member
• Posts: 3382
##### How long would it take for a black hole on Earth to swallow the Sun?
« Reply #25 on: 25/05/2010 17:37:44 »
My figure for the rotational speed may be somewhat in error as I took the the radius of an Earth mass BH as 0.5 cm whereas Hawking quotes 0.8864564 cm, perhaps someone would care to repeat the calculation with greater precision.

That's about the right figure, at least for a non-rotating BH.  I don't think it really needs greater precision.  After I initially worked out for myself, I didn't bother trying to remember the exact value; 'just under 9 mm' is good enough for most discussions

#### syhprum

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##### How long would it take for a black hole on Earth to swallow the Sun?
« Reply #26 on: 25/05/2010 18:11:17 »
My figure for the rotation of 10^15 rpm seems to coincide but as for the surface velocity I can only agree oops!.
« Last Edit: 25/05/2010 21:54:41 by syhprum »

#### Geezer

• Neilep Level Member
• Posts: 8328
• "Vive la résistance!"
##### How long would it take for a black hole on Earth to swallow the Sun?
« Reply #27 on: 26/05/2010 03:47:43 »
My figure for the rotation of 10^15 rpm seems to coincide but as for the surface velocity I can only agree oops!.

Ah! Only a few THz then.

#### The Naked Scientists Forum

##### How long would it take for a black hole on Earth to swallow the Sun?
« Reply #27 on: 26/05/2010 03:47:43 »