A black hole is an object in space with an infinite density and no characteristic boundary - called a singularity. Thus a black hole does not have a "size" but it's size is based on it's event horizon, rather than it's physical properties.
A black hole with the mass of our Sun, would have a diameter of about 6 km. (The Earth's diameter for comparison is about 12,500 km)
Black holes at the centre of galaxies are enormous and can have a mass up to several billion Suns. So they could have a diameter as large as 12,000,000,000 km. Approximately 12 times larger than our own Sun.
These are called supermassive black holes, because they are so big.
As of November 2008:
OJ 287 [See related links], is a binary pair of black holes. It contains the most massive black hole known, with a mass estimated at 18 billion solar masses.
It is located in the constellation Cancer at a distance of more than 3.5 billion light years.
Read more: How_big_is_a_black_hole
Read more: How_big_is_a_black_hole
They can be only a few miles across, while others are several million miles across.
A black hole can have a mass of about 50 billion suns, which is the limit.
Black holes can grow larger, depending what it sucks.
Since black holes are suns that have exploded, explosions spread, causing the black hole to emerge.
When our sun goes to the next stage in life, the black hole, it might not make a black hole, or a very small one.
In theory, there is no limit to how big they could get. The only limiting factor is the amount of material that can find its way into a black hole. So, it is possible for the whole universe, more than 70 sextillion (70000000000000000000000) stars and everything else affected by gravity to fall into a single black hole. What would happen after that is another question entirely.
Black holes are usually classified by mass; they can have the mass of a few suns (starting at perhaps 2 or 3 solar masses). The black hole in the center of our Milky Way (Sagittarius A*) is estimated to have about 4 million solar masses, while black holes in some other galaxies have billions of solar masses.
Since it absorbs even the sent light to measure its size cannot be measured.
The size of the black hole is too difficult for us to be able to measured. It is said to be really big and time stops near there. Also, it can even absorb light!
here is a previous qs that i answered may shed some light ?
i believe it is destroyed in a way that it cannot be altered back to its original form, like say if you have an object that gets sucked into a black hole, you would first have to take into account that the hole 'absorbs' light and it cannot run away. secondly the mass of the black hole can be infinity massive. your object would be deformed, if you will in such a way that space will be crumpled ( im English sorry ). basically the matter of the object will implode and explode thus meaning that due to the gravitational circumstanced the object will be destroyed in a way that cannot be imagined. as of time and space and light being destroyed by the hole it would mean that neither exist in the black hole, meaning that the object you put in the black hole may have an infinite mass or a minus infinite mass. regarding time the object could be ripped to shreds in miliseconds or slowly - yet the miliseconds sounds more appropriate.
sorry if you don't understand - im only 13 ;(
Before you can answer 'how big is a black hole?', you have to understand exactly what a black hole is. A black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull.
That definition leads you to wonder slightly about gravity. If, for some reason, you throw a rock straight up into the air it will rise for a while, but eventually the acceleration due to the planet's gravity will make it start to fall down again. If the acceleration is enough, you could make it escape the planet's gravity entirely. It would keep on rising forever. The speed with which you need to throw the rock in order that it just barely escapes the planet's gravity is called the "escape velocity." As you would expect, the escape velocity depends on the mass of the planet: if the planet is extremely massive, then its gravity is very strong, and the escape velocity is high. A lighter planet would have a smaller escape velocity. The escape velocity also depends on how far you are from the planet's center: the closer you are, the higher the escape velocity. The Earth's escape velocity is 11.2 kilometers per second and the Moon's is only 2.4 kilometers per second. After taking those two facts into consideration, look at a black hole. It is so massive that light does not travel fast enough to escape its gravity. Since nothing known travels faster than the speed of light, nothing can escape a black hole.
Now, back to the original question 'how big is a black hole?'. There are many different ways to describe how big something is. Let's just look at much mass it has and how much space it takes up. There is no limit(in principle) to how much or how little mass a black hole can have. In theory, any amount of mass at all can be made to form a black hole if you compress it to the right density. Most of the black holes were produced by the deaths of massive stars, so scientists believe those black holes weigh about as much as a massive star. A typical mass for such a black hole would be about 10 times the mass of the Sun, or about 1031 kilograms. Astronomers also suspect that many galaxies harbor extremely massive black holes at their centers. These are thought to weigh about a million solar masses.
the more massive a black hole is, the more space it takes up. In fact, the Schwarzschild radius(radius of the event horizon) and the mass are directly proportional to one another: if one black hole weighs ten times as much as another, its radius is ten times as large. A black hole with a mass equal to that of the Sun would have a radius of 3 kilometers. So a typical 10-solar-mass black hole would have a radius of 30 kilometers, and a million-solar-mass black hole at the center of a galaxy would have a radius of 3 million kilometers. Whether you measure by mass or space taken up, black holes can be some of the largest objects in the universe.
Well, the biggest KIND of black hole is the quazar (super massive black hole).
A super massive black hole may be millions or billions more massive than the sun.
The material sucked in to a black hole becomes part of the black hole - that is, a black hole crushes matter to an nearly no size, at all.
yes and no depends on size of hole :]
The size of a black hole, as defined by the size of the event horizon, depends on the mass of the black hole and its electrical charge. The diameter of the event horizon is directly proportional to the black hole's mass. Adding electrical charge decreases the size of the event horizon.
You would have a black hole the size of the combined mass of the two black holes.
The mass of the black hole would increase in proportion to the mass of the planet
The material sucked in to a black hole becomes part of the black hole - that is, a black hole crushes matter to an nearly no size, at all.
Any matter that enters the black hole will be destroyed. Also, it will increase the black hole's size.
A black hole can definitely get to the size of a planet. The width of the largest known supermassive black hole is thought to be over ten times the size of the entire orbit of Neptune around our Sun.
No.
yes and no depends on size of hole :]
The size of a black hole, as defined by the size of the event horizon, depends on the mass of the black hole and its electrical charge. The diameter of the event horizon is directly proportional to the black hole's mass. Adding electrical charge decreases the size of the event horizon.
You would have a black hole the size of the combined mass of the two black holes.
There isn't one. It depends on how much matter the collapsed star (black hole) has gathered.
Yes. Intermediate-mass blackhole is a medium size black hole. Scientists have found stellar black holes and supermassive black holes but there is no prove that Intermediate-mass black type of black holes exist. My opinion is that they do exist because when a black hole is becoming a black hole supermassiveblack hole it will need to go though this stage of intermediate-mass black hole.
yes
about 1/3 of a neutron star
Depends!!!A white dwarf created from a star the same size as our Sun will only be the size of our Earth.A supermassive black hole can have a diameter of 150 million kilometers (Same distance from the Earth to the Sun).However a stellar black hole can only be 30 kilometers in diameter.There is no minimum size for a black hole, so one "could" be as small as 0.1mm