Black holes are one of the most massive and
mysterious things in our universe. Formed
in the core of exploding stars, black holes
are a region of space time where gravity is
so strong that not even light can escape.
Once a black hole is formed it pulls in and
consumes all matter around it including gas
planets and even other stars. Through this
process, black holes can grow to become billions
of times more massive than even our own sun.
These super massive black holes are believed
to live at the centre of most or possibly
all of our 100 billion galaxies in the known
universe.
When the core of a dying star collapses, the
force of gravity exceeds the stars internal
degenerate pressure and pulls the star inward
prior to the inevitable supernova.
Once the massive explosion takes place all
that's left behind is the black hole, an
object of unimaginable density.
The core of a black hole is possibly made
up of quarks or other exotic material, at
this point we don't know. Surrounding this
core is a mathematical boundary called the
event horizon. This boundary is defined as
the point of no return. Anything, even light
that passes through it is trapped and will
fall into the core. This is the reason black
holes appear black!
Black holes can also form through high energy
collisions.
But don't worry; black holes created in
such a way would evaporate harmlessly in less
than a trillionth of a second.
Black holes in nature emit no light, yet we
know they exist... How?
Well we see evidence of black holes through
a process of gravitational lensing predicted
by albert Einstein in 1936 where light behind
the black hole is bent and distorted due to
the gravitational field.
Additionally we see stars at the centre of
the milky way galaxy rapidly orbiting a dark
area of space at relativistic speeds. The
velocity of these stars tells us that the
region has a mass of 4.3 million solar masses.
The only rational explanation for these orbital
periods is that a super massive black hole
resides at the centre of our galaxy a mere
26,000 light-years away! Although, rogue black
holes could be even closer.
