100 years of Hubble’s legacy.
A century ago, on the first day of 1925, an astronomical revelation changed the course of human understanding. During a pivotal presentation at an academic conference, Edwin Hubble presented evidence that shattered the notion of the Milky Way being the entirety of the universe. His findings confirmed the Andromeda Nebula as a galaxy far beyond our own, opening the door to an entirely new cosmic perspective.
At the time, the scale of the universe was vastly underestimated. The concept of other galaxies, let alone billions of them, seemed unfathomable. Hubble’s work was a monumental step in revealing the enormity of space and challenging humanity’s perception of its place in the cosmos.
From Speculation to Evidence
Long before Hubble, ancient civilizations viewed the heavens with wonder but little understanding. The Sun and stars were thought to be within reach until Eratosthenes calculated the Earth’s size and hinted at the vast distances in space. Over the centuries, incremental advancements, from measuring the Solar System to approximating the size of the Milky Way, gradually expanded our cosmic map.
Yet, the idea of galaxies beyond the Milky Way remained speculative until the early 20th century. Henrietta Leavitt’s groundbreaking work on Cepheid variables—a type of star with predictable brightness patterns—provided a crucial tool for measuring astronomical distances. By correlating a Cepheid’s apparent brightness with its actual luminosity, astronomers could estimate how far away it was. Leavitt’s findings allowed for rudimentary maps of the Milky Way and nearby dwarf galaxies like the Magellanic Clouds.
Despite this progress, existing telescopes lacked the power to detect Cepheids in more distant regions. It wasn’t until the advent of the 100-inch Hooker telescope that Hubble could observe these stars in the Andromeda Nebula. His precise measurements revealed that Andromeda was more than ten times farther away than the Magellanic Clouds, proving it was a separate galaxy entirely.
The Universe in Motion
Hubble’s discoveries did not immediately gain universal acceptance. Resistance within the scientific community persisted, but mounting evidence eventually silenced doubts. As astronomers embraced his findings, Hubble made another revolutionary observation: galaxies were not static. Instead, they were moving away from each other, with more distant galaxies receding faster. This phenomenon, known as the expansion of the universe, laid the foundation for the Big Bang theory.
Together, these discoveries redefined our understanding of the universe. They established its immense age—approximately 14 billion years—and its incomprehensible scale, with galaxies billions of times farther than our nearest stars. For many, this realization prompted a profound shift in worldview. Humanity, once thought to occupy a central role in creation, now seemed like a small part of an ever-expanding cosmic story.
A Century of Reflection
Hubble’s revelations forced humanity to confront its place in a vast, ancient universe. While some clung to disbelief, others found inspiration in the staggering beauty and mystery of the cosmos. Today, 100 years after Hubble’s groundbreaking presentation, his legacy continues to fuel exploration and awe. And so, as we uncover more of the universe’s secrets, we are reminded of how much there is left to learn—and how extraordinary it is to be part of this endless journey!
