3. BLACK HOLES: WHAT ARE
THEY?
Black holes are the evolutionary
endpoints of stars at least 10 to
15 times as massive as the Sun.
4. Facts and figures
Black holes are objects so dense that not even
light can escape their gravity , and since nothing
can travel faster than light, nothing can escape
from inside a black hole.
For example, if our Sun is magically crushed until
it becomes about 1 mile in size, it would become
a black hole, but the Earth would remain in its
same orbit.
Even back in Isaac Newton's time, scientists
speculated that such objects could exist.
5. FORMATION OF BLACK
HOLE
There are two main process constantly
going on in massive in stars: nuclear
fusion and gravitation. These two
dominates, the stars to collapse.
Once the star starts to collapse, it does not
stop, and the star will come inward upon
itself, resulting in the formation of a black
hole.
Only those stars greater than 3 times the
mass of sun that become Black Hole upon
collapse.
6. IF WE CAN’T SEE THEM, THEN HOW DO WE
KNOW THEY ARE THERE?
The X-rays are sent off into space and when they
strike the matter around the black hole , it can be
detected.
Binary X-ray sources are placed to find strong black
hole .
Another sign of the presence of a black hole is random
variation of emitted X-rays. And gravitational
lensing ,accretion disks n gas jets .
9. continue……………
Black hole weigh about as much as a star . It
would be aprox 10 times mass of sun .
More massive , more space it would require .
The size and mass have a simple relationship,
which is independent of rotation. According to
this mass/size criterion then, black holes are
commonly classified as :
Supermassive black hole
Inter-mediate mass black hole
Stellar-mass black hole
Micro black hole
10. HOW BIG IS A BLACK
HOLE?
Black holes weigh about as much as a massive
star. A typical mass for such a black hole would
be about 10 times the mass of the sun.
The more massive a black hole is, the more
space it takes up. A typical 10-solar-mass black
hole would have a radius of 30 kilometers, and
a million-solar-mass black hole at the center of
a galaxy would have a radius of 3 million
kilometers.
12. FALLING INTO A BLACK
HOLE
A black hole is a place where the force of gravity is so
powerful that you would need to be travel at a speed faster
than the speed of light to escape its pull. Since nothing in
the universe is faster than the speed of light, nothing that
falls into a black hole can ever escape.
The pulling force would increase as you moved toward the
center, creating what's called a "tidal force" on your body.
If you fell into a large enough black hole, no one outside
would be able to see you, but you'd have a view of them.
Meanwhile, the gravitational pull would bend the light
weirdly and distort your last moments of vision.
13. IF A BLACK HOLE EXISTED, WOULD
IT SUCK UP ALL THE MATTER IN THE
UNIVERSE?
A black hole has a horizon," which means a
region from which you can't escape. As long
asyou stay outside of the horizon, you can
avoid getting sucked in .
15. SUN AS A BLACK HOLE
Only stars that weigh considerably more
than the Sun end their lives as black holes.
The Sun is going to stay roughly the way it
is for another five billion years or so.
If the Sun *did* become a black hole for
some reason? The main effect is that it
would get very dark and very cold around
here. The Earth and the other planets would
not get sucked into the black hole; they
would keep on orbiting in exactly the same
paths they follow right now.
17. HUBBLE BLACK HOLE PHOTO
The strikingly geometric disk --
which contains enough mass to
make 100,000 stars like our Sun --
was first identified in Hubble
observations made in 1992.
18. BLACK HOLE SEEN IN CLOSEST
LOOK EVER
September 4, 2008—A super massive
black hole at the center of the Milky Way
has wound up in the crosshairs of a
virtual telescope spanning 2,800 miles
(4,506 kilometers).
Though unproven, there is strong
evidence for the existence of black holes.
20. NASA create a
three-dimensional
simulation of
merging black
holes. This was the
largest
astrophysical
calculation ever
performed on a
NASA
supercomputer.
