Looking
at the night sky, the bright moon, the stars blinking, you might have wondered – How big is the
Universe? It’s really difficult to wrap your head around the concept of
infinity and yet ever expanding Universe. So, let’s flip that question and ask
“How tiny are we?”
An
average human being is 5’ 2’’ to 5’ 7’’ or 1.6 to 1.7 m. That is pretty huge as
compared to most of the animal kingdom.
On a regular day when you are out doing your work along with the rest of
the world, you don’t feel tiny at all, that’s because the surrounding things
are on scale to your accessible level. If, for instance, you were to shrink to
the size of an ant, you would suddenly feel tiny (like Ant-Man) but that’s not
the point of the article.
Consider
the size of the earth in terms of its diameter, it’s roughly 12,742 km
(12,742,000 m). Do you notice the difference? But in the current state of
modernisation, people are travelling more than ever and can reach anywhere in
the world in one day as the air travel gets more affordable, so that might not
seem such a big comparison. Now consider the size of the largest planet in our
solar system – Jupiter. It has a diameter of 139,820 km (139,820,000 m) i.e.
earth is less than the 10th of that size. The fact that the distance
can still be mentioned in this article in meters or even kilometre for that
matter means that the comparison is just getting started!
Credits: NASA/JPL-Caltech
The
Sun - the star at the center of our solar system, around which each and every
object in the entire solar system revolves has a diameter of 1.3927 million km
(1,392,700,000 m) which is ten times the size of the Jupiter. Now the size of
our solar system i.e. from the Sun to the outermost edge is about 143.73
billion km, which gives a diameter of 287.46 billion km (287,460,000,000,000
m). The number is getting very big in comparison to the size of a human and we
are not even out of the solar system yet.
One
of the dimensions of our galaxy – the Milky Way is 9.461*1015 km
(9,461,000,000,000,000 m) and you might be surprised to know that it’s the
thickness which is estimated to be 1000 light years which means it takes the
light about a 1000 years to just cross through the thickness of the Milky Way. On
the other hand the Milky Way is 1*1018 km wide
(1,000,000,000,000,000,000 m) which is 105,700 light years.
Credits: European Space Agency
All
of this was just our resident stellar property. Let’s now move onto our nearest
interstellar neighbours – Andromeda galaxy. Astronomers estimate it to be 2.5
million light years away from us which is 2.365*1019 kilometres (23,650,000,000,000,000,000 m). Both of these galaxies along with some other
galaxies nearby belong to the Virgo cluster which is 15 million light years
wide i.e. 1.419*1020 kilometres (141,907,926,000,000,000,000,000 m).
Keeping
track of all the zeroes is getting really difficult now, and yet there is an
enormous part of the universe to measure. This Virgo cluster is a part of Virgo
supercluster which is 110 million light years wide hence 1.04*1021
kilometres (1,040,658,120,000,000,000,000,000 m) which in turn is a part of a larger
supercluster called Laniakea supercluster with 500 million light years diameter
of the spherical bubble which is 4.73*1021 kilometres (4,730,264,200,000,000,000,000,000 m) wide.
Since
the Big Bang, the Universe is continuously expanding for 13.8 billion years.
The actual size of the Universe haven’t been precisely measured due to the fact
that the light from farthest corners of the universe haven’t reached us yet and
also because the universe is expanding faster than the speed of light. So, the
part of the universe that we can actually see is termed as Observable universe
and is measured to be 93.016 billion light years which is hence 8.8*1023
kilometres (880,000,000,000,000,000,000,000,000 m). Seems to be a very gigantic number.
Hence we can say that a human is on average 0.000000000000000000000000193 %
times the observable universe which is practically ZERO and yet it is not the
whole universe!
Image taken by Voyager 1 (Earth is
the pale blue dot), Credits: NASA/JPL-Caltech