There are several black holes throughout space. A black hole is a

region of space where gravity's pull is so strong that nothing can escape it.

What is a black hole?What is a black hole?

• A black hole is a region of space where A black hole is a region of space where gravity’s pull is so strong that not even gravity’s pull is so strong that not even light can escape it. It is called “black” light can escape it. It is called “black” because it absorbs all the light that hits because it absorbs all the light that hits it, reflecting nothing. Although black it, reflecting nothing. Although black holes are invisible, astronomers know holes are invisible, astronomers know black holes exist because of the impact black holes exist because of the impact they have on the space around them.they have on the space around them.

How many types of black holes are How many types of black holes are therethere

• According to astronomists, there may be three types of black holes, the stellar, the super massive and the miniature black holes-depending on their size. Super massive black holes most likely exist in the centre of most galaxies, including our own galaxy, the milky way. They are named super massive if it has the equivalent size of billions of suns. Miniature black holes are the black holes that would only take within the existing time of our universe to evaporate. A stellar black hole is when its only about 20-30 times the suns mass and has been formed by a star.

Do all stars become Do all stars become black holes?black holes?

Not all stars do become black holes, Not all stars do become black holes, only stars with very large masses can only stars with very large masses can become black holes. Our sun, for become black holes. Our sun, for instance, is not big enough to become instance, is not big enough to become a black hole, in four billion years from a black hole, in four billion years from now the sun will die a quiet death, now the sun will die a quiet death, killing no one. More massive stars that killing no one. More massive stars that are more then 20 times the suns mass are more then 20 times the suns mass may eventually become a black hole.may eventually become a black hole.

How are black holes formed?How are black holes formed?

Black holes are formed when a star runs out of its Black holes are formed when a star runs out of its nuclear fuel that it needs to produce light, and it can nuclear fuel that it needs to produce light, and it can no longer hold its own weight and begins to collapse. no longer hold its own weight and begins to collapse. When this happens, a fraction of its outer layer that When this happens, a fraction of its outer layer that often still contains some nuclear fuel activates a often still contains some nuclear fuel activates a reaction, and the star explodes. Then the core of the reaction, and the star explodes. Then the core of the star continues to collapse and depending if the core is star continues to collapse and depending if the core is massive it will continue collapsing into a black hole. massive it will continue collapsing into a black hole. A smaller star will stop collapsing and turn into a A smaller star will stop collapsing and turn into a neutron star.neutron star.

What evidence do we have for the What evidence do we have for the existence of black holes?existence of black holes?

Astronomers have found convincing Astronomers have found convincing evidence for the existence of super massive evidence for the existence of super massive black holes in the center of several galaxies. black holes in the center of several galaxies. The biggest black hole is 3 billion times the The biggest black hole is 3 billion times the mass of our sun, in the centre of the ‘m87’ mass of our sun, in the centre of the ‘m87’ galaxy. The discovery is based on a galaxy. The discovery is based on a whirlpool of hot gas orbiting a big black whirlpool of hot gas orbiting a big black hole. For many years x-ray emissions from hole. For many years x-ray emissions from the ‘double star system Cygnus-1’ has the ‘double star system Cygnus-1’ has convinced many astronomers that the convinced many astronomers that the system contains a black hole. With much system contains a black hole. With much more precise measurements available more precise measurements available recently, there is very strong evidence for a recently, there is very strong evidence for a black hole in ‘Cygnus-1.’black hole in ‘Cygnus-1.’

What does a black hole What does a black hole look like?look like?

We are not sure what a black hole looks like, We are not sure what a black hole looks like, as they are invisible because no light can as they are invisible because no light can escape from it. Astronomers can still identify escape from it. Astronomers can still identify black holes by examining the effects on the black holes by examining the effects on the objects around them. They study clouds of gas objects around them. They study clouds of gas and stars moving at a very fast pace, and and stars moving at a very fast pace, and normally conclude that there is a black hole in normally conclude that there is a black hole in that vicinity after further research. When a that vicinity after further research. When a smaller black hole and star orbit each other, smaller black hole and star orbit each other, the black hole can be identified by astronomers the black hole can be identified by astronomers when the black hole starts pulling light from the when the black hole starts pulling light from the star.star.

BibliographyBibliography

►HubbleSite - Reference Desk – FAQsHubbleSite - Reference Desk – FAQs►http://cosmology.berkeley.edu/Educatiohttp://cosmology.berkeley.edu/Educatio

n/BHfaq.htmln/BHfaq.html►http://spaceplace.nasa.gov/en/kids/blahttp://spaceplace.nasa.gov/en/kids/bla

ckhole/index.shtmlckhole/index.shtml►http://design.lbl.gov/education/blackhohttp://design.lbl.gov/education/blackho

les/index.htmlles/index.html

►http://imagine.gsfc.nasa.gov/docs/ask_http://imagine.gsfc.nasa.gov/docs/ask_astro/black_holes.htmlastro/black_holes.html

ConclusionConclusion

I have now thoroughly answered all I have now thoroughly answered all of my questions and my opinion is of my questions and my opinion is

that a black hole is like a giant that a black hole is like a giant cosmic vacuum cleaner that sucks up cosmic vacuum cleaner that sucks up

anything that floats into its path. I anything that floats into its path. I wonder if the sun really will die a wonder if the sun really will die a

quiet death…..?quiet death…..?Thanks for watching my PowerPoint Thanks for watching my PowerPoint

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