What is the approximate size of a black hole with about 5 Solar masses?
371914
A 5 solar mass Black Hole (assuming static, non-rotating, non-acreting) would have a radius of about 15 km.\n\nThe Swartzchild radius gives the radius of a static, non-rotating, non-acreting black hole as:\nR = 2GM/c^2\nA rule of thumb is that the radius is about 3km per solar mass.
621324
Around 105 light years, or 3x10^5 km/s * 365 * 24 * 3600s * 105 km, or 993 384 000 000 000 km, or 617 277 076 989 996 mi
790352
click here:http://en.wikipedia.org/wiki/Rotating_black_hole
166469
7.349 x 10 ^22 kg - every night! (source: NASA) :)\n\nThe apparent size of the moon varies.  Check this link for an explanation:\n\nhttp://www.space.com/scienceastronomy/solarsystem/bigmoon_000105.html
473814
General relativity (as well as most other metric theories of gravity) not only says that black holes can exist, but in fact predicts that they will be formed in nature whenever a sufficient amount of mass gets packed in a given region of space, through a process called gravitational collapse. For example, if you compressed the Sun to a radius of three kilometers, about four millionths of its present size, it would become a black hole. As the mass inside the given region of space increases, its gravity becomes stronger — or, in the language of relativity, the space around it becomes increasingly deformed. Eventually gravity gets so strong that nothing can escape, an event horizon is formed, and matter and energy must inevitably collapse into a singularity.
729339
About .39 astronomical units.
964413
Some examples of measurements where scientific notation becomes useful follow.\n\nThe wavelength for violet light is 40-millionths of a centimeter 4 × 10-5cm. \nSome black holes are measured by the amount of solar masses they could contain. One black hole was measured as 10,000,000 or 1.0 × 107 solar masses. \nThe weight of an alpha particle, which is emitted in the radioactive decay of Plutonium-239, is 0.000,000,000,000,000,000,000,000,006,6 45 kilograms (6.645 × 10-27 kilograms). \nA computer hard disk could hold 4 gigabytes (about 4,000,000,000 bytes) of information. That is 4.0 × 109 bytes. \nComputer calculation speeds are often measured in nanoseconds. A nanosecond is 0.000000001 seconds, or 1.0 × 10-9 seconds.
63870
Not much is known about black holes. What is known is only an estimate of how it might work.
1136303
A black hole is not actually a hole, but a physical object in space, consisting of ultra compact particals, contained in such a small area that thier gravitational pull is much stronger than any other celestial body of comperable size....  Basically you put all the matter and gravitational pull from a large star into the volume of a small moon... particles captured by a black hole are crushed and added to its composition. This in theory includes photons (light and other energy)as well.  As for whether black holes are hoax's or not.. the answer is no... we can see their effects on star near them, including gases that are syphoned, and other gravitational interactions.  Additionally when matter approaches a black hole and is accellerated, it reaches an energy level at the even horizon where xrays are emited, but not captured, which in turn we can also detect.  Though there is much we do not know about them, they definately exist, and most likely in much greater numbers than we oringinally thought.
148361
Size of Star depends on how it was formed originally. I don't think it could be said precisely. U can take the size of our sun as a measure. Radies=6400kms
730167
Very close to the mass of a proton.  It is about 1.6749 x 10^-27 kg, 1 u, or 939.57 MeV/c^2.
520554
Small black holes disappear in a puff of Hawking radiation, pretty rapidly.\n\nThey don't really need containment. They just evapourate into thermal radiation.  It's only the dirty great big ones that could smash the place up.  Making one of these on earth is just not feasible.  The ones that occur naturally in the universe are rather a long way off.\n\nNothing to worry about.
752294
The event horizon of a Black Hole is spherical.\n\nThe circumference is 2 pi times the radius, where the radius here means something rather different than "the distance to the center", since space is so warped.\n\nThe radius is proportional to the mass of the black hole (not the cube root of the mass, as you might at first think).  The radius is about 10 kilometers for the mass of the Sun, so 20 kilometers for twice the mass of the Sun, etc.
913686
This is a simple ratio problem. The equation would be Dgalaxy/Dearth=Dearth/x so x=(Dearth)^2/Dgalaxy. Asssuming a parsec is 3.6 light years, and a light year is 5.87 trillion miles and the diameter of the Earth is 8,000 miles, then the Earth would be 0.001 millimeter or one micron in size, which is the size of an average bacterium, maybe? Very cool. Oops! I re-did my calculation and I see that I made a factor of ten error. The correct answer is about 0.1 microns, or the size of some viruses. But tell me how you would make such a model of the Earth?
273528
The defining factor of a black hole is that the escape velocity is higher than the speed of light.  This is a function of density and not total mass.  It's possible to have very small black holes.  They can even have masses smaller than that of an atom.  The LHC at CERN, which is expected to come online in 2007, may be capable of producing such microsingularities.  \n\nAs for our universe being a black hole...  from inside it's certainly not.  But, from "outside", if you can define such a thing, maybe it does appear as such, since light cannot escape out universe.  This assumes, however, that there is an outside from which this can be considered, and there's no proof, and perhaps no way to prove, whether or not there is.
1170344
Sobrien, thats a really incorrect thoery.  The Sun wont even be able to turn into a black hole.  Am I the only person who knows what thier saying!?\n\nAnyway, the Sun, in 4.5 billion years supposivly, will start to swell.  It will get bigger, and engulp Mercury and Venus.  The atmosphere will evaporate, water will melt, and life will be gone.  The sun will swell enough to devour the earth, then shrink, grow, Turn into a planetary nebula, then shrink, for the last time, into a white dwarf.  Then In a few billion years, cool down to a black dwarf.\n\nThe reason the sun expands, Incase you want to know, Is because of its fuel supply.  The energy from the sun comes from nuclear fusion of Helium.  When the helium supply runs out, The sun has to fuse hydrogen, therefore making the sun swell.  The sun then will Shrink, once its helium supply is restored, grow again, then cast out a planety nebula (For what a planetary nebula looks like, Look up the ring nebula) then it wont have enough hydrogen to grow back to the normal size...and become a white dwarf.  Eventually, it will cool into a black dwarf and die.
658056
The Schwarzschild radius(for those who want to be a pain in the butt, yes this is a simplified equation for a nonrotating mass but for our purposes should be a good approximation) is 2GM/c^2 where G is the gravitational constant 6.67e-8 dyne cm^2 g^-2, M is the mass of the object, and c is the speed of light(use cm/s^2 as units).  Basically when all the mass is contained within a radius smaller than this value, the gravitational metrics go a little crazy and this is defined to be a black hole.\n\nI leave it to you to do the math, see whether the accepted radius of a nucleus is within this radius or not and there is you answer.  There are other forces at play that cause the strong attractive forces within a nucleus, particularly strong nuclear force.  If this was gravity(which from above you should see the radius is a lot smaller than the radius of the nucleus in order to cause such effects), then the electrons would be sucked into nucleus as well, since you would have both an attractive coloumb force and an attractive strong gravitational force.\n\nThat being said, you would not see radiative activity if the nucleus was a black hole.