Astronomy Through the Ages: Pioneers, Observations, and Paradigm Shifts

The night sky has from the beginning awed us with stars and comets catching our attention. Our ancestors used these stars to sail across the seas. Many saw animals or objects and called them constellations. It was only after many millenniums that we could give mathematical treatment to astronomy. Before that philosophers just speculated and observed the night sky and tried to give explanations such as, what is a comet? Is the Earth a sphere or a cylinder? Are celestial beings responsible for Earth’s movement? Well, it took humanity a long time to answer these questions and today we will know how we have described the motion of planets by peeking through our windows.

Greek had their views

To summarize Greek astronomy, Greeks just said what they saw. Like they observed the sky and speculated their observations. They saw Earth as a flat disk they thought this was it. At least it was for Thales of Miletus (624-546 BCE) who is also known as the first Greek philosopher believed that Earth is a circular shape disk floating on water. And Sun and moon are celestial divine beings. Later philosophers like Plato and Aristotle proposed the geocentric model of the solar system (Erath as a center with the sun and moon revolving around it).

The Geocentric model prevailed and became the most widely accepted model for the coming centuries. It was only after the Scientific Revolution during the 16th century that the heliocentric model got wide acceptance. Just for a fun fact, the Greek philosophers believed that the motion of the earth and other objects were due to celestial beings or angels pushing them in orbits.

The Scientific Revolution and Astronomy

With the advent of the scientific revolution in the 16th century, many scientists to name a few, Nicolaus Copernicus, Johannes Kepler, Galileo Galilei, and Sir Isaac Newton gave their works in the field of astronomy and it was because of these people that we know answers that were puzzling us from the histories.

Copernicus proposed his heliocentric model in his seminal work, “De Revolutionibus Orbium Coelestium” (On the Revolutions of the Celestial Spheres), which was published in 1543, just before his death. And challenged the most widely accepted geocentric model.In this book, Copernicus outlined his theory that the sun, rather than Earth, was the center of the solar system and that the planets, including Earth, orbited the sun.

Johannes Kepler in early 17th century formulated his laws of planetary motion based on the extensive observational data collected by Tycho Brahe, a Danish astronomer. Kepler’s laws became the basis for the upcoming revolution in astronomy. His works helped Newton to formulate his universal gravitational law. Both Newton’s gravitational law and Kepler’s planetary laws mutually demonstrate consistency, and each can be employed to substantiate the other. It was also this time in 1609 when after hearing about the “Danish perspective glass” in 1609, Galileo constructed his own telescope. What Galileo did was to improve the magnification of the lens. Using the telescope he looked into the heavens. He saw the phases of the moon, the four moons of Jupiter which further strengthened the heliocentric model given by Copernicus.  

The Marriage of Physics and Astronomy

Until the 1900s we were only concerned with astronomical observation and astrophysics as a subject only developed when advances were made in the field of physics and mathematics. The most prominent one was the Theory of general relativity by Albert Einstein in 1915 which provided the explanation for gravity. And gave the model for the fabric of space-time and how both are related to each other. In 1929, Edwin Hubble announced that almost all galaxies appeared to be moving away from us. In fact, he found that the universe was expanding – with all of the galaxies moving away from each other. This phenomenon was observed as a redshift of a galaxy’s spectrum. Now we knew the universe was not static but expanding. Rebuffing the steady state theory of the universe.

 Now with technological advancement and giant telescopes and observatories in both space and on land. We have come to know about distant galaxies, black holes, and gravitational waves. But honestly what we know is just a tip of an iceberg. We still are figuring out what dark matter and dark energy are. We still don’t know many things about our own sun. But the quest continues to explore and dive deep into the cosmic ocean. Who knows what or who awaits us!!

Also, read on what will be the fate of our universe, will it keep expanding like what Hubbel said or it will stop at some point in time?

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