Image: The image shows a central portion of the Hubble Deep Field, created from exposures taken in 1995. The Hubble Deep Field covers a piece of sky about 1/13th the diameter of the full Moon.
Credit: NASA, Robert Williams, and the Hubble Deep Field Team (STScI)
Image: The image shows a central portion of the Hubble Deep Field, created from exposures taken in 1995. The Hubble Deep Field covers a piece of sky about 1/13th the diameter of the full Moon.
Credit: NASA, Robert Williams, and the Hubble Deep Field Team (STScI)

One hundred years ago, on January 1, 1925, Edwin Hubble forever altered humanity’s view of the cosmos by announcing the discovery of galaxies beyond the Milky Way. Until then, the prevailing belief was that the Milky Way contained all the universe. Hubble’s groundbreaking work challenged this assumption, proving that our galaxy is just one of countless others scattered throughout the vastness of space.

Using the 100-inch Hooker Telescope at Mount Wilson Observatory in California, Hubble observed the Andromeda Nebula, previously thought to be a cloud of gas within the Milky Way. Hubble calculated its distance from Earth by identifying and studying a particular type of star known as a Cepheid variable. The results were astonishing: Andromeda lay well beyond the boundaries of the Milky Way, establishing it as an entirely separate galaxy.

This discovery was the beginning of extragalactic astronomy, fundamentally expanding our understanding of the universe’s scale and structure. Hubble also developed a classification system for galaxies based on their shapes, including spirals, ellipticals, and irregulars. His subsequent observations revealed that galaxies are receding from us, providing the first evidence for the universe’s expansion—a cornerstone of the Big Bang theory.

Hubble’s findings reshaped not only astronomy but also humanity’s place in the cosmos. His work demonstrated that the universe is vastly larger and more dynamic than anyone had imagined, prompting a profound shift in both scientific inquiry and philosophical perspective. Today, Hubble’s legacy endures in the Hubble Space Telescope, a modern marvel that continues to explore the distant reaches of space, honouring the man whose vision redefined our view of the universe.

Written with the help of ChatGPT













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