Spring Astronomy Day – May 3, 2025

History of Spring Astronomy Day

Humans have been looking to the heavens for several millennia now. Thus, it is not surprising that astronomy is one of the oldest natural sciences known to man. The discipline finds its roots in not just a rational, objective spirit of inquiry but also in religion, mythology, cosmology, and astrology, among other human practices. Early cultures identified celestial objects with deities and spirits. They related natural phenomena to divinity, looking to explain what was unexplainable otherwise. Every culture around the globe has had such beliefs — for example, the Greek “Zeus” ruled over the skies, the Egyptian “Ra” was the sun himself, and the Indian “Chandra dev” was the moon incarnate. The earliest astrologers were, thus, priests, and they looked at celestial bodies as divine — this view of astronomy is what constitutes the subject matter of astrology.

Babylonian astronomers saw the sky as a celestial sphere and organized stars into constellations. The ancient Greeks developed their belief system based on empirical evidence they collected from observing the movement of the stars. They propounded a geocentric model of the universe, in which a spherical Earth was stationary at the center of the universe. This model had wide acceptance in Western Civilizations for the next two millennia; only when Copernicus proposed a heliocentric (a solar system with the sun at the center) model did things change. Isaac Newton and Christian Huygens, among others, accepted this cosmology. Thinkers and philosophers like Kant, Wright, and Herschel ensured that the discipline of astronomy continued to evolve.

The modern era of physical cosmology, a branch of astronomy, began in 1917 when Einstein applied his general theory of relativity to the dynamics of the universe. Two later discoveries by Edwin Hubble further changed people’s perceptions of the universe. He first showed that the Andromeda galaxy was both separate from and similar to our own Milky Way galaxy. Subsequently, he discovered and proved the movement of distant galaxies away from one another as though the universe was expanding. Today, astronomy is an intersection between physics, chemistry, and meteorology; however, its goal is the same as that of the first priests who set out to map the heavens — ‘understanding the workings of the universe.’