Black holes (astronomy) I have some questions?

Question

What is a black hole and how is it formed?
What does it look like?
What are like the features of it? What's so important?
Who discovered it?

Answer 1

What I will tell you is that there is a lot of debate about how black holes are formed. They are not fully understood, so expect to get some different answers.

Check these out for some great content. Sorry gotta go to work, don't have time to explain it. Cheers!


http://www.physorg.com/news95598170.html

http://space.newscientist.com/article.ns?id=dn12089&feedId=online-news_rss20

Answer 2

A black hole is the remants of a massive star that has collapsed in on itself, it is more than likely spherical in shape, like almost everything else in the universe. it can't be seen because light can't escape its gravity, a blck hole could be the size of a pin head head or as big as a mile or two in diameter, the area around a black hole where space is so tightly curved is called an event horizon, beyond that point not even time exists because the densiy of the matter allows no movement to take place, no movement, no time. Robert Oppenhimer, while investigating the properties of a neutron star predicted th prababily of the existance of black holes, in 1939.

Answer 3

What is a black hole and how is it formed?
A black whole is like a giant Vacuum in space, so powerful it sucks in even light. It forms whena supermassive star collapses in on itself.

What does it look like?
It doesn't look like anything, the only way scientists find them is from areas where it is totally black where there ordinarliy would be light.

What are like the features of it? What's so important?
Many scientists believe that Black holes make up the centers of galaxies.

Who discovered it?
...

Answer 4

A black hole is were the very fabric of space is torn.If you hold a paper you see it as a flat surface.A black hole is when a super nova acures and it rips that paper.So if you put a funnel under that paper thats how to black hole is.A black hole isnt really black.Black is all the colors and white is the absence of colors.So in a black hole it is all the colors comeing in so fast you can't see anything.No one has ever seeen a black hole, it is teryetical.

Answer 5

a black hole is when a star dies and its so big instead of exploding it implodes, so all of its matter and stuff just goes in on itself until the whole mass of a star is just like a little speck of dust. then because its so small but so massive it sucks up everything around it because of its graviatationnal forces. its called a 'black' hole because its so heavy and such a huge g-force that not even light can escape it, so theres no way to really 'see' one.

Answer 6

it doesnt look like anything. you wouldnt be able to see the black hole.

its created when a massive star dies and explodes. its basically all of the matter of a star compacted into a single point called the singularity.

the gravity of the black hole is massive, its so massive that not even light can escape it, which is why you cant see it.

Answer 7

A black hole is a region of space whose gravitational field is so powerful that nothing can escape it once it has fallen past a certain point, called the event horizon. The name comes from the fact that even electromagnetic radiation (i.e. light) is unable to escape, rendering the interior invisible. However, black holes can be detected if they interact with matter outside the event horizon, for example by drawing in gas from an orbiting star. The gas spirals inward, heating up to very high temperatures and emitting large amounts of radiation in the process.[2][3][4]

While the idea of an object with gravity strong enough to prevent light from escaping was proposed in the 18th century, black holes as presently understood are described by Einstein's theory of general relativity, developed in 1916. This theory predicts that when a large enough amount of mass is present within a sufficiently small region of space, all paths through space are warped inwards towards the center of the volume, forcing all matter and radiation to fall inwardly.

While general relativity describes a black hole as a region of empty space with a pointlike singularity at the center and an event horizon at the outer edge, the description changes when the effects of quantum mechanics are taken into account. Research on this subject indicates that, rather than holding captured matter forever, black holes slowly leak a form of thermal energy called Hawking radiation.[5][6][7] However, the final, correct description of black holes, requiring a theory of quantum gravity, is unknown.


Sizes of black holes
Black holes can have any mass. Since gravity increases in inverse proportion to volume, any quantity of matter that is sufficiently compressed will become a black hole. However, when black holes form naturally, only a few mass ranges are realistic.

Black holes can be divided into several size categories:

Supermassive black holes that contain millions to billions of times the mass of the sun are believed to exist in the center of most galaxies, including our own Milky Way.
Intermediate-mass black holes, whose size is measured in thousands of solar masses, may exist. Intermediate-mass black holes have been proposed as a possible power source for ultra-luminous X ray sources.
Stellar-mass black holes have masses ranging from about 1.5-3.0 solar masses (the Tolman-Oppenheimer-Volkoff limit) to 15 solar masses. These black holes are created by the collapse of individual stars. Stars above about 20 solar masses may collapse to form black holes; the cores of lighter stars form neutron stars or white dwarf stars. In all cases some of the star's material is lost (blown away during the red giant stage for stars that turn into white dwarfs, or lost in a supernova explosion for stars that turn into neutron stars or black holes). NB: Supernovae Can Only Occur With Red Supergiants
Micro black holes, which have masses at which the effects of quantum mechanics are expected to become very important. This is usually assumed to be near the Planck mass. Alternatively, the term micro black hole or mini black hole may refer to any black hole with mass much less than that of a star. Black holes of this type have been proposed to have formed during the Big Bang (primordial black holes), but no such holes have been detected as of 2007.
Astrophysicists expect to find stellar-mass and larger black holes, because a stellar mass black hole is formed by the gravitational collapse of a star of 20 or more solar masses at the end of its life, and can then act as a seed for the formation of a much larger black hole.

Micro black holes might be produced by:

The Big Bang, which produced pressures far larger than that of a supernova and therefore sufficient to produce primordial black holes without needing the powerful gravity fields of collapsing large stars.
High-energy particle accelerators such as the Large Hadron Collider (LHC), if certain non-standard assumptions are correct (typically, an assumption of large extra dimensions). However, any black holes produced in such a manner will evaporate practically instantaneously, thus posing no danger to Earth.
A black hole is defined by the velocity that would have to be attained to escape from its gravitational pull, which is termed the escape velocity. Within some distance from a black hole, this velocity would be greater than the speed of light - in other words infinite energy would be required to accelerate away from the black hole. For example, the escape velocity of the Earth at the surface is equal to 11 km/s. For an object to escape the Earth's gravitational pull at the surface without applying additional energy (i.e. unpowered), ignoring the effects of drag, it must go at least 11 km/s, regardless of its mass or density. On the other hand, the escape velocity at the surface of a gravitational body is related to its density - the ratio of its mass to radius - since the velocity required diminishes as one moves away from the center of mass. It is theoretically possible for objects with very small masses to be so dense that light couldn't escape, within a correspondingly small radius, however black holes are usually postulated as objects on the scale of the mass of stars or much greater.