Discoveries that Shaped our Understanding of the Universe – Who revolves around whom?
Since time immemorial, humans have been fascinated by
looking at the night sky. We, as a species, have always been intrigued by what
we cannot comprehend. The vast expanse of the universe with its endless count
of celestial bodies is something that continues to remain partially explored.
History stands witness to how man and his curiosity have passed on the flag of exploration
of heavenly bodies over generations, thus enriching our understanding of the observable
universe. Today, let us delve deeper into a small basket of such
ground-breaking discoveries!
As a part of this series, we will be covering and uncovering
some of the biggest discoveries that have shaped our understanding of the
cosmos.
Who revolves around whom? Are we sure the Earth isn’t stationary?
It was in the year 230 BC, that the Greek philosopher
Aristarchus came up with the theory that the Earth revolves around the Sun. Prior
to this, and for many more years to come, humans still believed in the ideology
of the Earth being at the center of the universe.
Polish Astronomer, Nicholas Copernicus, in his 1543 book titled,
‘On the Revolution of the Heavenly Spheres’, demoted Earth from being the center
of the universe to just another planet orbiting the Sun. This gave birth to the
Copernican Principle, that states that our position in the universe is completely
ordinary. The Copernican Principle has since become a pillar of modern cosmology.
Galileo, in the year 1610 AD, pointed his telescope to the hottest
planet in our solar system and the second-brightest object in the night sky. To
his amazement, he saw the Earth’s ‘sister’ planet going through phases, just
like the moon. Galileo correctly deduced that this could happen only if the
orbit of Venus was closer to the Sun than Earth’s orbit.
But how can we be sure that the Earth is but moving and not
stationary?
Let us understand this with a simple example. Imagine standing
on open ground, with the rain coming straight down at you. To prevent
yourself from getting drenched, you’d have to hold your umbrella right above
your head. However, if you begin to walk, you’d have to tilt the umbrella into
the rain, in front of you. The faster you walk, the greater would be the tilt.
The same concept applies to the movement of the Earth
through the cosmos. As the Earth orbits the Sun, we can detect a tilt of the
incoming light from stars. The British astronomer, James Bradley, was searching
for stellar parallax when he discovered this phenomenon by accident in the year
1725. This aberration of starlight was observed and is a result of light having
a finite speed and the motion of our planet around the Sun.
In the upcoming article in this series, we will be touching
base upon how the discovery of the telescope proved to be a milestone in
astronomical research and changed the way humans observed the night sky.
Stay tuned to The Tipsy Marketer!
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