Viswanathan K's Thoughts

Ever wondered why the shift to a sun-centric model of the planets was so important? Forget the religious aspect of it: have you ever wondered why it should matter if we consider the sun or the earth to be at the center? After all, isn’t all motion relative? I’ll answer that by starting with a new question: If the planets were moving around the earth, what would their orbits look like? They would be insanely complicated, with planets crisscrossing, and even reversing directions at times! This pic shows how their orbits look with a heliocentric (sun-centric) v/s geocentric (earth-centric) model: With such weird trajectories in the geocentric model to explain, I am guessing even Newton would have struggled to apply his laws of gravitation! Copernicus’ model made the problem statement so much simpler, didn’t it? Yet another instance of how changing your perspective can change your understanding of the universe dramatically!

Refer to my blog on the planetary models of the old days. This blog, again based on Kitty Ferguson’s Tycho and Kepler , focuses on the first half of the Tycho-Kepler pair, a Danish nobleman cum astronomer par excellence: “Tycho Brahe was renowned throughout Europe as a prince among astronomers and an astronomer among princes.” Tycho believed that “the future of astronomy lay in numerous and exact observations”. To that purpose, he designed sophisticated instruments, many of which required “highly skilled, specialist instrument makers”. In 1572, he saw a new object in the sky, brighter than any other star or planet: -          He determined that it wasn’t a comet. -          He figured it lay beyond the Moon, a contradiction to Aristotle’s point that nothing changed in the regions beyond the Moon. He published all this in a book, De Stella Nova , meaning The New Star. An ironic title given t...

Tycho Brahe and Johann Kepler are one of the great pairs of science. The former collected immaculate data from his observations of the skies; which the latter then analyzed to come up with his famous laws of planetary motion. Very fairy tale like, right? Except that reality was far more complicated, as Kitty Ferguson describes in Tycho and Kepler , her awesome biography of the two men, their personal lives and their science. This blog, the first in a four-part series, explains the prevailing astronomical views before Brahe and Kepler changed our understanding forever. There was Ptolemy’s model, with the Earth at the center, and everything else orbiting the Earth. In this model, planets seemed to slow down and accelerate at times and even reverse direction: this is because we on Earth are moving in a circle while observing the other planets. Hence the concept of epicycles (circles within circles) was added to the model: How did the epicycles help describe the observed m...