Universe Guide

What is a Black Hole?

Black Hole Facts

What is a Black Hole ?

In short, a Black Hole is an object in space whose gravity is so powerful that nothing can escape its gravity pull. The common theory for their creation is that they are created when a massive star explodes. A massive star being one at least three times the mass of our Sun . All stars will die eventually, once their fuel has runs out. When they do, they become one of three items in space, a white dwarf, a neutron star or a black hole. Particles from the star that do not form into one of those will journey into space and get pulled into being an object round another star. It is believed that a star close by Earth exploded and its left over material was used in the creation of our planets.

A black hole's gravity is so strong that they can pull in light. They can destroy anything that gets in their way including our own Sun and any Star even if they're ten times bigger than the star that our planet orbits. If you were in a space ship that is faced with a black hole in its path, you would be lucky to escape. The Black hole would pull you into its core and crush you to a pulp. If you end up being pulled into a black hole, your ship will be destroyed and then spurted out either at the top or the bottom of the black hole. It has been estimated that there could in fact be 100 million black holes in our galaxy alone.

Whilst light is not strong enough to escape from a black hole, Dark Energy is strong enough to escape the pull of a Black Hole. Dark Energy is unaffected by gravity so Black Holes can not capture it. Cornell

They're out there, you can't see them like you can see the planets, the moon or the stars but they are there. It is because they are the same colour as the void of space that we can't see them straightaway. With a bit of patience and the right equipment, we can find them.

Cygnus X-1, HDE 226868

The most famous Black hole that has been discovered is "Cygnus X-1", no points for guessing its in the constellation of Cygnus, the Swan. The picture below is N.A.S.A's artists impression of what Cygnus X-1 looks like. Cygnus X-1 is close to a star and feeding off it, pulling matter from the Sun into the hole. The star that is nearest to the black hole is name HDE 226868. Ref: N.A.S.A.

Artists Impression of Cygnus X-1

NASA's artists impression of Cygnus X-1 black hole feeding off a nearby star.

Location of Cygnus X-1

Rough Location of Cygnus X-1 Black Hole

Since the 1970s, more have been discovered. The only way to spot one is to watch an area of space; if the lights from the stars change inexplicable then it could be put down to the fact that the light is being affected by the black hole. A black hole could be close by but we would get some time to escape. They move slowly through space. There's no knocking it off course like we would with a meteor. The only thing we could do is run and find another solar system to inhabit if we get the technology in time. The above diagram shows roughly where the black-hole is in relation to the constellation.

For those that think that our solar system or even the universe is in some sort of Black Hole, I can honestly say it isn't. Jagadheep D. Pandian explains on the linked page why we are not in a Black Hole. Essentially, he is saying that space time is inverted in a black hole but our reality is not like that.

How did Black Holes get their name?

The term "Black Hole"'s creation is credited to physicist John Wheeler who came up with it 1967. The concept of a Black Hole wasn't new at the time, it had been theorized before then. Dark Stars or even Frozen Stars had been theorized beforehand, they were described as being so gravitationally strong that not even light could escape. Black Holes are not stars, they are the remnants of dead stars. Cornell Uni

Black Holes in Science Fiction

Some people particularly those in science fiction and science theorists think black holes are portals to another world or even universe. For the moment, they will be just that, theory and science fiction.

Black Holes have featured in science fiction such as in Disney's eighties film 'The Black Hole' where a scientist plans to travel through a Black Hole and take some unwilling passengers along for the ride. It has also featured in Andromeda where the main protagonist Dylan Hunt was trapped in the Event Horizon of a galaxy

Are Black Holes Wormholes and what happens if you are sucked into one?

Wormhole and Black Holes are two different concepts but they could be linked. A wormhole is a tunnel to link two parts of space with one another. A Black Hole is the last stage of a star's life after it has gone supernova for some stars. Another form of death for a star is that a White Dwarf star or as a neutron star.

Attempting to go through a Black Hole would cause your body to contort, stretch and thin, leading to a horrible death, that is if you're not dead already. A Black Hole would probably not lead to another part of the galaxy as it did in the Disney film.

Time would occur differently that to an observer as Gravity warms space and time. Time would slow down the closer you got to the black hole. Time slowing down was a feature that was used in Andromeda series when the Andromeda Ascendant gets trapped in an event horizon.

Prof. Stephen Hawking did actually think that a black hole might actually be a wormhole and that if you're trapped in one, you may be able to find your way out. It could even lead to a parallel universe within the Multiverse. The Sun

Event Horizons and Size of a Black Hole

There are three sizes of Black Hole, Primordial, which are about the size of a single atom but its mass can be as much as a mountain. A primordial black hole could essentially be created when a meteor hits the Earth's atmosphere. There's nothing to worry as they are so small, there would be no effect on us down on planet Earth. Ref: IFL Science

The most common form of Black Holes are stellar Black Holes which are created when a star collapses in on its self. They can have a mass twenty times the mass of the Sun but in size, they could be no bigger than a 20 mile diameter sphere. They're the most common because they out number the largest black holes which is next.

The third type of Black Hole is the largest, the supermassive black hole which we'll just touch on now, they are at the centres of galaxies through the universe. Ref: N.A.S.A

Event Horizon

The Event Horizon is the point at which the escape velocity is equal to the speed of light. However, having fallen into a black hole, it s not possible to escape no matter what speed you are able to do. The space inside a black hole is curved in on itself so no direction will get you out of the black hole. Cornell When people talk about the size of the Black Hole, it is not size of the centre but the distance from the centre of the Black Hole to the Event Horizon.

How do we spot a Black Hole and do they actually exist?

You can't look up into the sky and spot a black hole because they and the space that they inhabit is black. You look for tell tale signs that they are about. The motion of other stars nearby can give you an idea that a black hole is nearby. You can see a black hole when it is devouring a star like in the case of Cygnus X-1 as below or you can see it as it moves in front of something. The below picture from N.A.S.A. is an artists impression.

No one has actually seen a Black Hole partly because they are black and also because they are so far away. Neptune, the planet was theorized before it was actually discovered and Black Holes are like that, they've been theorized but not yet been seen. Precise measurements of Cygnus X-1 indicate a very strong likelihood of a black hole existing there. Hubblesite

A black hole could creep up on without us spotting it but there would be tell tale signs it was coming, changes in gravity of the Sun and surrounding space. There's has been no changes been noticed so we are safe for now and for a very long time, Reference is the same as the one in the previous section.

Black Hole, Neutron Star and White Dwarf, which path will a star take?

The path that a star will take will depend on its size. Our Sun, which in comparison to us is massive, it is also small compared to other stars in the universe. Our Sun is a pea compared to the size of VY Canis Major which is the size of a house. Although not exactly proportionally, it is to give you some idea of how small our Sun in. Or put it another way, if YV Canis Major was in the place of the sun, it diameter would extend to past Jupiter. There are even bigger stars out there such as the UY Scuti.

Getting back to the subject in hand, a star the size of the Sun would become a White Dwarf. A white dwarf will shine for years and years eventually turning into a black dwarf. Given the believed number of years it takes for a white dwarf to become a black dwarf, there are no black dwarfes out there. If the star is over 1.4 times the size of the Sun, it will turn into a Neutron Star. A Neutron star is a star full of Neutrons hence its name. The biggest stars will collapse in on themselves and be so gravitationally strong that they become black holes. The diagram at N.A.S.A. will be explain what I'm saying.

What is a White Hole?

In contrast to a black hole, a white hole is the theorized other end of a black hole. All the material that is sucked into a black hole is ejected out through a white hole as the theory goes. Whilst nothing can escape from being pulled into a black hole if you're too close, the reverse of the white hole is nothing can get into a white hole. It is believed a White Hole has been discovered on June 14 2006 by the N.A.S.A. Swift satellite. The hypothetical white hole formally known as GRB 060614 was discovered by the satellite noticing an extraordinary powerful Gamma-Ray Burst in the minor constellation of Indus.

Gamma-Ray Bursts tend to last seconds, this particular GRB lasted for 102 seconds which is why they believed it to be a sign of a possible White Hole. The features of the GRB matched with what we knew about White Holes hence the opinion it was a white hole. The GRB didn't emanate from an area of a such as being in a region of low star formation or a supernovae event taking place. Ref: Astronaut

If white holes do exist, where are they? Surely, not all the black holes are pointing to us and all the white holes are pointing away from us? According to this paper, white holes are a spontaneous ejection of energy similar to the Big Bang. They do exist for as long as black holes, seemingly eject and then die.

What is a Supermassive Black Hole?

The name gives it away, they're bigger and more powerful than the regular black holes such as Cygnus X-1. These black holes are at the centres of galaxies such as our own the milky way. The location of our own Supermassive is on the borders of constellations Sagittarius and Scorpius and is about 25,000 light years plus or minus a few thousand. The picture below is roughly where the centre of the galaxy is. If you can locate Al Nasl and follow on diagonal direction upwards, you should see it but its probably not visible with the naked eye though. These Black Holes can be grouped into Radio Galaxies, Blazars and quasars as they can all be active, shooting particles from their centres to millions of miles away.

Supermassive Black Holes can contain millions or billions times the mass of a regular black hole hence why they're named so. As to how the Supermassive Black Holes were created, the jury is still out on this one. There are theories that a black hole at the centre of the galaxy just grew over the millions and billions of years to what they are today by consuming material from stars or other black holes.Ref: Swinburne University

Rogue Supermassive Black Hole

Whilst most galaxies will have a supermassive black hole, one galaxy has opted to get rid of theirs. In the galaxy 3c 186 in the constellation of Lynx, the supermassive black hole is moving out of its central location. The most likely explanation is that it had collided with another supermassive black hole and was forced out. The speed at which it is moving out of its quasar is 1,300 miles a second. To put that into comparison, is orbiting its central galaxy at a speed of 15 miles a second. Ref: Extreme Tech

Death of the Universe and Black Holes

Like humans, the Universe will be born, live and then die. It was born 13.8 Billion Years ago give or take thousands of years, it is currently "living" and then as stars fade, some will turn into white dwarf stars then into black dwarf. Some will turn into black holes and they will become very prominent in the Degenerate Era, once the Stelliferious Era, the Era of the stars has ended. There's not enough atoms in the universe to signify how long until the universe is back to what it was like before the big bang.

Hawkings Radiation

Black Holes are dead remnants of stars, they also have a finite life span. When the Universe ceases to exist, Black Holes will be the last remaining evidence of the universe but over time, Black Holes will themselves dissipate and die out.

According to Prof. Stephen Hawkings, black holes will radiate energy due to quantum mechanical processes, this radiation is called Hawkings Radiation. As the Black Hole radiates energy, it will shrink and finally disappear. A Black Hole with the mass of the Sun will take more than a billion times a billion times a billion times a billion times a billion times a billion times the age of the universe to disappear completely. Its a number that is incredible to think about. Cornell

Black Holes need to be fed to continue to exist because of the leakage. Hawkings Radiation is only a theory which has not been proven or disproved. It is said that had it been proved, he would have won the Nobel Prize for science for it.

Black Hole Collisions

In September 2015, LIGO (Light Interferometer Gravitational Wave Observatory) announced that they had found evidence of gravitational waves caused by a collision between two black holes 1.3 billion light years from Earth.

Gravitational Waves were first theorized by Albert Einstein in his theory of relativity but only known proven. The exact location in terms of constellation hasn't been released but they've said the constellation is a southern hemispheric constellation so that rules out Ursa Minor and others then. Ref: Caltech

Collision course with a Black Hole

To spot a black hole, you look for a dip in brightness as the black hole moved across the skyline. We wouldn't know about it until it came to within a light year away from us, about the distance the Oort Cloud is from us. The comets in the cloud would be sent towards us but the real scary stuff is when it comes closer as it will pull apart the asteroids in the kuiper belt sending them towards us. The black hole would easily rip apart the gas giants and then move closer towards us. Life on the planet would be destroyed long before it hit us.

There are no black holes nearby so don't be having nightmares and dreaming about them because its unlikely to happen, As the article says, the odds of being hit by a black hole is one in a trillion. You have better chance of being hit by lightning. ref:SpaceAnswers

Our galaxy is on a collision course with the Andromeda galaxy but that will be so far in the future, billions of years in fact but when it does happen the two supermassive black holes at the centres of each galaxy will collide and create a new black hole. The result will be new star creation.

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amazing, so where is the closest black hole to our universe, and when would we kn ow if it would hit us
Tom Jenner
so how many black holes we got in our solar system and what plannet did Trance gemini came from
All of the above might night be true. To Elbert Einstein he could be right that black holes end in a defferent dimention then ours. I think he could be correct and how do scientist know that black holes bassicaly crush us? I bet noone knows that. I think that it is rather like a worm hole or time rip maybe.
Michael Conn
Do we know if the speed of light is constant? At what speed does matter become anti matter?
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