A Small Piece of Glass

It was a small piece of glass, illuminated on a wooden table in a Pasadena library, with a few handwritten markings and one particularly enthusiastic exclamation point.

More than a century ago, that glass plate helped change humanity’s understanding of the universe.

On Tuesday, Rep. Judy Chu joined astronomers and historians at Carnegie Science Observatories to celebrate “Beyond the Milky Way Day,” commemorating Edwin Hubble’s 1923 discovery that the universe extended far beyond our own galaxy.

The gathering took place in the historic Hale Library, surrounded by towering shelves of astronomical journals, a portrait of pioneering astronomer George Ellery Hale and a chalkboard crowded with equations.

At the center of the celebration was Hubble’s original photographic plate, rarely displayed publicly, bearing the handwritten notation “VAR!” that marked a discovery of extraordinary importance.

“I was so astounded to learn of this magnificent discovery right in our backyard,” Chu told the gathering.

On Oct. 5, 1923, Hubble was observing the Andromeda nebula through the 100-inch Hooker telescope at Mount Wilson Observatory when he photographed what he initially believed was another nova, a star that suddenly brightens.

Further observations revealed something different: a Cepheid variable star, whose regular changes in brightness could be used to calculate its distance.

Using a relationship discovered by astronomer Henrietta Swan Leavitt, Hubble established that Andromeda lay far beyond the Milky Way. What astronomers had thought was a cloud within our galaxy was actually another galaxy altogether.

The universe, it turned out, was vastly larger than anyone had imagined.

Carnegie Science President John Mulchaey called the finding one of the most significant scientific achievements in four centuries.

“What I love about it is you can see Edwin Hubble’s excitement about the discovery,” Mulchaey said, describing the famous exclamation point.

He noted that the plate is so rarely displayed that he had worked at Carnegie for 20 years before seeing it himself.

The observatories maintain approximately 250,000 photographic plates, preserved from an era when astronomers recorded the night sky on glass rather than digital sensors.

Dan Lewis, the Huntington Library’s curator for the history of science and technology, described the institution’s extensive collection of Mount Wilson records, including Hubble’s papers and observing notebooks.

The historical materials, he said, remain heavily used by researchers.

Tuesday’s celebration also carried a contemporary political message.

Chu recently introduced a congressional resolution recognizing Oct. 5 as “National Beyond the Milky Way Day.” She used the occasion to emphasize continued federal support for scientific research, including NASA and its Science Mission Directorate.

“Their achievement is a powerful reminder what we can accomplish when we invest in scientific research, discovery and collaboration,” she said.

Mulchaey, meanwhile, offered a broader reflection on why astronomy continues to matter.

“Astronomy gives us perspective on the universe, the world and everything around us,” he said.

After the speeches, guests were invited to approach the illuminated plate for a closer look.

There, beneath the library’s shelves of scientific history, was Hubble’s modest handwritten exclamation point, marking the moment when the known universe suddenly became much, much bigger.

And it’s still expanding. Every day.