Man thinks that he has invented so many
things and there is no one better than us. Astronomy should studied by such a
person and he realizes how insignificant and senseless man is in the universe.
Man defines God in his image. Since he has love, God
must have love, and since he has hate, God must have hate. God must be angry because he is angry. Man
projects all his attributes on to God. Eventually he
makes God to even think like him.
Most of us know nothing about astronomy. Because when we study,
in some books even if astronomy is mentioned briefly, they never touch on cosmology.
I hope that the write-up given below will
interest you in astronomy. In the Mahabharata, Krishna showed his Viswaroopa to
Arjuna. The Bhagavad Gita gives a wonderful description of the universe. It is said to be
brighter than 1000 suns. Gods, demons, mankind and
the entire universe appear in that Viswaroopa. It is
said to have no beginning, middle or end and contains everything we know or do
not know. It is called the unknowable, incomparable
and incomprehensible.
It is difficult to predict the time when
Bhagavad Gita was composed. Probably in the 3rd century BC. At that time there was no other literature in the world that
showed the universe to be of such a large size.
To measure the enormous distance between
stars, scientists introduced a unit called the light year. Light travels at a speed
of 300,000 KM per second (2,99,792 Km/Sec to be exact). The distance light travels in one year at this speed is called a
light year. This is equivalent to about 9.46 lakh
crore km.
Even the description in the Bhagavad Gita is
not enough to describe the universe as we know it today. If you look up at the
dark night sky, how many stars can you see? Many say
countless. But it is not so. There are only about 3000 stars that we can see with the naked
eye.
But when using telescopes for viewing, the
visible stars increase manifold. 50,000 stars can be seen with an ordinary
binocular and about 3,00,000 stars with a 2 inch telescope. A 330-inch telescope can see stars 1200 million light-years away.
This telescope is so powerful that it can detect the light
of a candle lit on the moon.
Currently the largest telescope in the world
is the “Gran Telescopio Canarias” in Spain. Its diameter is 409
inches. The range of telescopes can be very high, but
these telescopes can only see 5% of the known universe. The rest of the universe can only be seen through radio
telescopes.
NASA has sent telescopes into space so that
we can get a better understanding about the Universe. It launched the Hubble
Space Telescope in 1990. Based on the data from this telescope about 18000
scientific papers were published. Most recently in Dec 2021 a more advanced
James Webb Space Telescope had been sent into space by NASA. This telescope is
some 100 times more powerful than the Hubble and can see track infrared
emissions. This is giving us invaluable data to us now and perhaps some 100,000
scientific papers would be published based on the data.
In fact the entire Universe seen by us
through all our instruments is only 5% and the rest 95% consist of Dark Matter
and Dark Energy which we cannot detect with any of our instruments, but their
gravitational effect can be seen on many stars. This is how we know that Dark
Energy exists.
Stars emit electromagnetic rays of light
with different wavelengths. Some emit radiation with very short
wavelengths, while others emit radiation with very long wavelengths. Radiation with very short wavelengths is absorbed by molecules in
our atmosphere. Radiation with very long wavelengths
is reflected back by the ionosphere.
The radiation that reaches us has a
wavelength ranging from 0.0004 mm (violet radiation) to 0.0008 mm (red
radiation). Only these are visible to our eyes. Another
type of radiation that reaches us from stars is radio waves. This radiation has longer wavelengths than the VIBGYOR spectrum,
but is not long enough to be reflected by the Earth's ionosphere.
These waves show much more of the universe
than the reflecting telescopes. These waves created the field of radio
astronomy. The world's largest radio telescope is
located in Arecibo, Puerto Rico. Its diameter is
about 1000 feet.
Our Sun is of course the closest star to us. As you know all the
planets revolve around the Sun. The Sun is 14 crore
80 lakh kilometres away from us. But that is only a
minuscule distance in space.
The distance of the nearest star Proxima
Centauri from the Sun is 4.2 light years away or about 40 lakh crore
kilometers. Our Sun is in a galaxy called the Milky Way (galaxy means a large
group of stars and it also includes clouds of dust). There
are one hundred thousand billion (10 raised to the power of 12) stars in our
galaxy, the Milky Way. Its diameter is one hundred
thousand light years.
The Andromeda Galaxy is the closest galactic
neighbour to the Milky Way. Its distance from us is 29 million light years.
There are about 100 billion such galaxies spread across the known
universe. The diameter of the universe as we know it is 13800 million light
years.
Now, even the distance of 1 light year at
9.46 lac crore Km passes right above our head. So our minds even fail to
register the distance of 13800 million light years.
As I mentioned earlier the Universe has 100
billion or 10,000 crore Galaxies. Each of these Galaxies on the average contain
about 100,000 crore stars. Thus the total number of stars in the known Universe
aggregates to 10 raised to the power of 23. Our Galaxy itself comprises of
100,000 crore stars. In this massive ocean of stars our sun is just an average
star without any significance whatsoever.
And again our instruments and even
estimations take us only up to the end of the known Universe. What is beyond
this we do not know and have absolutely no means of even making a guess.
Perhaps after the Universe maybe billions of light years of open space and then
after that another Universe? We can only speculate on that.
When we read Astronomy we can understand our
insignificance in the Universe and it inculcates humbleness into us.