By Anabel Delgado,Carlos Martín and Andrés Ortiz.1ºE

IN THIS PRESENTATION YOU WILL SEE:

-WHAT’S A BLACK HOLE?

-HOW DO BLACK HOLES FORM?

-THEORETICAL CLASSIFICATION

-COULD A BLACK HOLE DESTROY THE EARTH?

-COULD THE SUN TURN INTO A BLACK HOLE?

-IS THERE ANY BLACK HOLE NEAR THE EARTH?

-HOW DO WE APPOINT A NAME TO THE BLACK HOLES?

-STEPHEN HAWKING

WHAT’S A BLACK HOLE? A black hole is one of the strangest objects in

space. It is an area in space where gravity is so

strong that even light cannot escape from it.

Since light cannot escape from a black hole, it

appears black. Light can travel faster than

anything we know with a speed of 300,000

kilometers per second. If light cannot escape

from a black hole, nothing else that we know

can.

A black hole is not really a hole and it is not

empty. It is filled with a lot of material

crammed into an extremely small space. This is

what gives a black hole its super strong gravity.

HOW DO BLACK HOLES FORM?

Primordial black holes are thought to have

formed in the early universe, soon after the

big bang. 

Stellar black holes form when the center of a

very massive star collapses in upon itself.

This collapse also causes a supernova, or an

exploding star, that blasts part of the star

into space. 

Scientists think supermassive black holes

formed at the same time as the galaxy they

are in. The size of the supermassive black

hole is related to the size and mass of the

galaxy it is in. 

THEORETICAL CLASSIFICATIONAccording to his origin, theoretically there can exist at least three classes of black holes:

According to the mass:

- Black supermassive holes: With masses of several million solar masses. They would be situated in the heart of many galaxies. They are formed in the same process that gives origin to the spherical components of the galaxies.

-Black holes of stellar mass: They are formed when a star of mass twice major that of the Sun turns in supernova and implosion . His core centers in a very small volume that every time is diminishing more. This one is the type of black holes postulated by the first time inside the theory of the general relativity.

- Mike black holes: They are hypothetical objects, something smaller than the stellar ones. If they are sufficiently small, they can evaporate in a relatively short period by means of emission of Hawking's radiation. This type of physical entities is postulated in some approaches of the quantum gravity, but they cannot be generated by a conventional process of gravitational collapse, which needs masses superior that of the Sun.

COULD A BLACK HOLE DESTROY

THE EARTH? No,because the orbit of a black hole would have to be very close to the Solar System to affect the Earth.

If a black hole with the same mass and gravity as the Sun replaced it,the Earth would not fall into,on the contrary,the planets would still orbiting the black hole as they orbit the Sun.

But if an object or person could aproximate to a black hole, first it comes stretched like a spaghetti and finally it will disintegrate in small particles.

COULD THE SUN TURN INTO A

BLACK HOLE? No. The stars as the Sun

are not sufficiently massives to turn into a black hole. It would happen, a thousand of years later, that the Sun will repel it’s external layers and its nucleus will form a white dwarf: a dense ball of carbon dioxide and oxygen that now doesn’t produce nuclear energy, but it shines according to its high temperature. The mass of a white dwarf is the same as the Sun’s mass, but its size is almost like the Earth, so it’s a one percent of the Sun’s actual diameter.

IS THERE ANY BLACK HOLE NEAR THE EARTH?

The nearest black holes discovered at the moment are at various thousands of light years away. They are so far that they don’t have any effect in the Earth neither in it’s surroundings. It is believed that there is a supermassive black hole in the middle of our galaxy, the Milky Way, at about 27.000 light years away. Although it has millions of times the Sun’s mass, as being so far it can’t affect our Solar System.

27.000 light years

HOW DO WE APPOINT A NAME TO THE BLACK HOLES?

There is not an unified system to give name to the black holes. Supermassive black holes in the nucleus of one galaxy they have the name of it. Also they can be named by the machine used for it discovery, for example, Cignus X-1, that was discovered with X-rays.

A name that starts in NGC are included in the new general catalogue, that was compiled in 1888 and amplified in later years. Some black holes are catalogued by the constelations they are in, and in the order that they were discovered.

My name is Cignus X-1

STEPHEN HAWKING Stephen Hawking was a

very important scientist that has studied a lot about black holes. He investigated and discovered that some black holes emited a special type of radiation. For this reason, this radiation is called Hawking radiation.

He has also written a book about black holes, which is called Black Holes and Baby Universes and Other Essays.

THE END