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

2. 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

3. 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.

4. 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.

5. THEORETICAL CLASSIFICATION
According 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.

6. 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.

7. 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.

8. 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

9. 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

10. 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.

11. THE END