Where did Edwin Hubble make his discovery?

Peering into Infinity: How Edwin Hubble Rewrote the Cosmos from a California Mountaintop

Edwin Hubble. Just the name conjures up images of distant galaxies and the vastness of space, doesn’t it? He’s practically a household name when it comes to understanding the universe. But where, exactly, did this cosmic revolutionary do his groundbreaking work? Picture this: perched high above Southern California, atop Mount Wilson, at the Mount Wilson Observatory. That’s where the magic happened.

Think of Mount Wilson Observatory as the Silicon Valley of astronomy in the early 20th century. Founded in 1904, it was the place to be if you wanted to unlock the secrets of the cosmos. And the observatory boasted some serious hardware, including the 60-inch reflector and, the real star of the show, the 100-inch Hooker telescope. This wasn’t your backyard telescope; the Hooker, completed in 1917, was the biggest in the world until 1949! It was the “right tool” that allowed Hubble to make observations that would change everything.

Hubble arrived at Mount Wilson in 1919, just as the Hooker Telescope was starting its regular science observations. Back then, the common belief was that the Milky Way was it – the entire universe. Nebulae, those fuzzy blobs of light in the sky, were a mystery. Were they simply clouds of gas and dust within our own galaxy, or something…more? This was the question that Hubble set out to answer.

Using the 100-inch telescope, Hubble began meticulously photographing these nebulae. Then, one night – October 5-6, 1923, to be exact – while observing the Andromeda Nebula (M31), he spotted something he initially thought was a nova, a star suddenly flaring up in brightness. But after taking more photos, he realized it was something far more significant: a Cepheid variable star.

Now, Cepheid variables are like the astronomer’s best friend. They’re these incredibly useful “standard candles.” You see, Henrietta Swan Leavitt had previously figured out that there’s a direct relationship between a Cepheid’s brightness and how long it takes for its light to fluctuate. Measure the period, and you know how bright it really is. By measuring the period of the Cepheid in Andromeda, Hubble could calculate its distance. And that’s when the bombshell dropped.

His calculations put Andromeda at a staggering 900,000 light-years away. That’s way, way beyond the Milky Way. Boom! Andromeda wasn’t just some nebula within our galaxy; it was an entirely separate galaxy in its own right. Suddenly, the universe got a whole lot bigger. Over the next decade, Hubble’s research revealed millions of other galaxies, all previously mistaken for nebulae. Talk about a paradigm shift!

But Hubble wasn’t done yet. By measuring the distances and velocities of these galaxies, he stumbled upon another mind-blowing discovery: the universe is expanding! In 1929, working with Milton Humason, he showed that a galaxy’s distance is directly related to how fast it’s moving away from us. This became known as Hubble’s Law. The farther away a galaxy is, the faster it’s receding. It’s like the universe is one giant loaf of raisin bread dough, and all the galaxies are raisins moving away from each other as the dough rises.

This discovery was huge. It strongly supported the Big Bang theory, the idea that the universe started from a single point in the distant past. Now, Hubble’s initial calculations for the expansion rate (what we call Hubble’s Constant) weren’t quite right, but the core idea was spot on.

Edwin Hubble continued his research at Mount Wilson, revolutionizing our understanding of the cosmos. Later, he even helped design the 200-inch Hale Telescope at Palomar Observatory.

Today, Hubble’s legacy lives on through the Hubble Space Telescope, named in his honor. Launched in 1990, this orbiting telescope continues to send back breathtaking images and data, pushing the boundaries of our knowledge about the universe that Edwin Hubble first unveiled from his mountaintop observatory. It’s a testament to the power of human curiosity and the endless wonders that await us in the vast expanse of space.