This text was initially revealed at The Conversation. The publication contributed the article to Area.com’s Expert Voices: Op-Ed & Insights.
Every part in house – from the Earth and Solar to black holes – accounts for simply 15% of all matter in the universe. The remainder of the cosmos appears to be manufactured from an invisible materials astronomers name dark matter.
Astronomers know dark matter exists as a result of its gravity impacts different issues, corresponding to gentle. However understanding what darkish matter is stays an lively space of analysis.
With the discharge of its first images this month, the Vera C. Rubin Observatory has begun a 10-year mission to assist unravel the thriller of darkish matter. The observatory will proceed the legacy of its namesake, a trailblazing astronomer who superior our understanding of the opposite 85% of the universe.
As a historian of astronomy, I’ve studied how Vera Rubin’s contributions have formed astrophysics. The observatory’s identify is becoming, on condition that its knowledge will quickly present scientists with a option to construct on her work and shed extra gentle on darkish matter.
Vast view of the universe
From its vantage level within the Chilean Andes mountains, the Rubin Observatory will doc every part seen within the southern sky. Each three nights, the observatory and its 3,200 megapixel digicam will make a report of the sky.
This digicam, in regards to the measurement of a small automobile, is the largest digital camera ever built. Photos will seize an space of the sky roughly 45 occasions the dimensions of the total Moon. With a giant digicam with a large subject of view, Rubin will produce about 5 petabytes of information yearly. That’s roughly 5,000 years’ worth of MP3 songs.
After weeks, months and years of observations, astronomers can have a time-lapse report revealing something that explodes, flashes or strikes – such as supernovas, variable stars or asteroids. They’ll even have the biggest survey of galaxies ever made. These galactic views are key to investigating darkish matter.
Galaxies are the important thing
Deep subject photographs from the Hubble Space Telescope, the James Webb Space Telescope and others have visually revealed the abundance of galaxies within the universe. These photographs are taken with an extended publicity time to gather probably the most gentle, in order that even very faint objects present up.
Researchers now know that these galaxies aren’t randomly distributed. Gravity and darkish matter pull and information them right into a construction that resembles a spider’s net or a bathtub of bubbles. The Rubin Observatory will increase upon these earlier galactic surveys, rising the precision of the information and capturing billions extra galaxies.
Along with serving to construction galaxies all through the universe, darkish matter additionally distorts the looks of galaxies via an impact known as gravitational lensing.
Gentle travels via house in a straight line − except it will get near one thing huge. Gravity bends gentle’s path, which distorts the way in which we see it. This gravitational lensing impact offers clues that might assist astronomers find darkish matter. The stronger the gravity, the larger the bend in gentle’s path.
Discovering darkish matter
For hundreds of years, astronomers tracked and measured the movement of planets within the photo voltaic system. They discovered that each one the planets adopted the trail predicted by Newton’s laws of motion, aside from Uranus. Astronomers and mathematicians reasoned that if Newton’s legal guidelines are true, there should be some lacking matter – one other huge object – on the market tugging on Uranus. From this hypothesis, they found Neptune, confirming Newton’s legal guidelines.
With the flexibility to see fainter objects within the Nineteen Thirties, astronomers started monitoring the motions of galaxies.
California Institute of Know-how astronomer Fritz Zwicky coined the time period darkish matter in 1933, after observing galaxies in the Coma Cluster. He calculated the mass of the galaxies primarily based on their speeds, which didn’t match their mass primarily based on the variety of stars he noticed.
He suspected that the cluster might include an invisible, lacking matter that stored the galaxies from flying aside. However for a number of a long time he lacked sufficient observational proof to help his concept.
Enter Vera Rubin
In 1965, Vera Rubin turned the primary girls employed onto the scientific employees on the Carnegie Establishment’s Division of Terrestrial Magnetism in Washington, D.C.
She labored with Kent Ford, who had constructed an especially delicate spectrograph and was seeking to apply it to a scientific analysis challenge. Rubin and Ford used the spectrograph to measure how briskly stars orbit across the heart of their galaxies.
Within the photo voltaic system, the place many of the mass is inside the Solar on the heart, the closest planet, Mercury, strikes sooner than the farthest planet, Neptune.
“We had anticipated that as stars bought farther and farther from the middle of their galaxy, they might orbit slower and slower,” Rubin said in 1992.
What they present in galaxies stunned them. Stars removed from the galaxy’s heart have been shifting just as fast as stars closer in.
“And that actually results in solely two prospects,” Rubin explained. “Both Newton’s legal guidelines don’t maintain, and physicists and astronomers are woefully afraid of that … (or) stars are responding to the gravitational subject of matter which we don’t see.”
Knowledge piled up as Rubin created plot after plot. Her colleagues didn’t doubt her observations, however the interpretation remained a debate. Many people were reluctant to just accept that darkish matter was essential to account for the findings in Rubin’s knowledge.
Rubin continued learning galaxies, measuring how briskly stars moved inside them. She wasn’t excited by investigating darkish matter itself, however she carried on with documenting its results on the movement of galaxies.
Vera Rubin’s legacy
Right now, extra individuals are conscious of Rubin’s observations and contributions to our understanding of darkish matter. In 2019, a congressional invoice was launched to rename the previous Large Synoptic Survey Telescope to the Vera C. Rubin Observatory. In June 2025, the U.S. Mint released a quarter that includes Vera Rubin.
Rubin continued to build up knowledge in regards to the motions of galaxies all through her profession. Others picked up the place she left off and have helped advance dark matter research over the previous 50 years.
Within the Nineteen Seventies, physicist James Peebles and astronomers Jeremiah Ostriker and Amos Yahil created computer simulations of individual galaxies. They concluded, equally to Zwicky, that there was not sufficient seen matter in galaxies to maintain them from flying aside.
They prompt that no matter darkish matter is − be it cold stars, black holes or some unknown particle − there could possibly be as a lot as 10 occasions the quantity of darkish matter than unusual matter in galaxies.
All through its 10-year run, the Rubin Observatory ought to give much more researchers the chance so as to add to our understanding of darkish matter.
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