GAMMA RAY BURSTS (GRBs)
Gamma-Ray bursts or
GRBs are the most violent explosions in the Universe. They occur when two
Neutron stars collide and form a black hole, or when a black hole swallows a
neutron star or when a Star goes “SUPERNOVA”, that means there is a sudden and
great increase in the brightness because of a catastrophic explosion that
ejects most of its mass. Just imagine, 2 massive stars (which are like 50 to
100 times the mass of our sun) colliding. It is hard to imagine such an event
without witnessing. As far as Human knowledge goes, GRBs are the ‘BRIGHTEST’
electromagnetic events ever known. Each burst can last from 10 milliseconds to up to several
hours. They’re outside the spectrum of visible light, hence are
invisible to the naked eye.
The Sources of GRBs:
Most of them are located
billions of light-years from earth (one light-year is equal to 1079000000
kilometres). So it’s fair to say that they occur somewhere very very far from
earth). This also implies that the explosions that give rise to these GRBs are
extremely Energetic (A typical GRB releases more energy in a matter of few
seconds, than our Sun will do in its entire lifetime of 10 billion years).
The Discovery of these GRBs
are very recent to be fair. First discovered by the ‘VELA’ Satellites in 1967,
(which were originally designed by the United States to detect Nuclear Weapons
tests), all the information which were gained were declassified and published
in 1975. In the following years, many Scientists and astronomers created hundreds of theoretical models to explain these bursts, but no one could
verify them until 1997. In that year, a group
of scientists detected the first X-Ray and optical afterglows of these GRBs. They were able to study
direct measurements
of the Redshifts (a phenomenon where an electromagnetic wave
undergoes an increase in its wavelength) using Optical Spectroscopy (Study of
interaction of Matter and Radiation) to figure out their distances and energy
outputs.
Generally, these GRBs are very far from earth
more prominently away from our Milky Way Galaxy, so they hardly have any effect on the planet. Human beings
have been able to detect multiple GRBs over the last decade. They are named after the date on which they are detected.
For Example,
GRB 670702 (The First
detected GRB)
Here, the first two numbers correspond to the year, the second two numbers
correspond to the month and the last two numbers to the
day.
So, We Come to the Main
Question.
WHAT WILL HAPPEN IF A GAMMA-RAY BURST HIT OUR PLANET?
Well, one can say that we
will surely feel their effect if it hits
our planet. One of these Bursts might even result
in mass extinction here on earth. But that mighty event was around
450-500 million years, long before even the first dinosaur started roaming the
planet.
A BURST FROM 3000 LIGHT YEARS AWAY FROM EARTH
The effects wouldn’t be too
bad. Even though the Earth would absorb most of the radiation emitted, the only
danger prevails with our satellites. Some may
get knocked offline permanently. People might
lose their internet connection, but it wouldn’t take long for us to restore the
malfunctioning satellites.
A BURST FROM 500 LIGHT YEARS AWAY FROM EARTH
This would change the game
completely. The Radiation that would rain down on our earth would completely
destroy our ozone layer. Almost all our plant species would die. There wouldn’t
be enough plants sustaining. The plant processes like photosynthesis may reduce and
hence the amount of oxygen in our atmosphere would drastically reduce. Plant eating animals would starve, and the rest of them would be
left to suffocate. Humans could try to save themselves with Oxygen masks,
but even that wouldn’t help us too long.
A CLOSE CONTACT WITH THE EARTH (WITHIN 200 LIGHT YEARS)
The Damage would be equivalent to the earth
getting hit by an asteroid. First, it would immediately destroy our atmosphere
and as a result, the human beings would come in direct contact with UV rays, getting
severe sunburns, and we’re probably trying to figure out how to restore the
planet’s atmosphere, before this hostile environment, killed us completely,
There is still good news.
Gamma rays have such a short wavelength, that luckily the beam may pass
relatively close and do no cause significant damage.
Absolutely nothing would be
as devastating as the direct gamma-ray burst within our galaxy. But our
satellites would detect the burst immediately.
What would we
do once we find ourselves in the crosshairs of
this all-natural galactic phaser?
As the burst will start
approaching our planet, Photons would be pulling away the Ozone layer away,
Causing Chemical reactions on earth.
If you’re standing on your
roof, you’d see a cloud of photochemical smog covering the planet. We would be
blasted with all sorts of Cosmic rays. They would damage our Electronics and
bring us lethal doses of radiation. We would witness another Wave of Mass
Extinction on earth.
THE GOOD THING!
Well, It Doesn't look like
that an event like this is likely to happen for Another billion years. By that
time, we might have figured out a way to stop a blast of that magnitude, or how
to move the earth from its danger zone.
It seems we have to wait for another
Millennia to find out.
-Soumya Deep Phadikar
Department-Biotechnology
1st Year
References’:
. www.earthsky.org
. www.astrobio.org
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