by Everything in the room – from the earth and the sun to black holes – accounts for only 15% of all matter in the universe. The rest of the cosmos seems to be made of an invisible material that astronomers call dark matter.
Astronomers know that dark matter exists because gravity influences other things, such as light. But understanding what dark matter is, remains an active research area.
With the release of his first images this month, the Vera C. Rubin Observatory started a 10-year mission to help unravel the mystery of dark matter. The observatory will continue the legacy of his namesake, a groundbreaking astronomer who has advanced our understanding of the other 85% of the universe.
As a historian of astronomy, I studied how the contributions of Vera Rubin have formed astrophysics. The name of the observatory is appropriate, given that the data will quickly offer scientists a way to build on her work and shed more light on dark matter.
Wide view of the universe
From the viewpoint in the Chilean Andes Mountains, the Rubin Observatory will document everything that is visible in the southern sky. Every three nights, the observatory and the 3,200 megapixel camera will make a record of the air.
This camera, about the size of a small car, is the largest digital camera ever built. Images catch an area of the air about 45 times the size of the full moon. With a large camera with a wide field of vision, Rubin produces about five petabytes of data every year. That is about 5000 years of MP3 numbers.
After weeks, months and years of observations, astronomers will have a time-lapse record that reveals everything that explodes, flashes or movements-such as supernovas, variable stars or asteroids. They have also made the largest overview of galaxies ever. These galactic views are the key to examining dark matter.
Galidals are the key
Deep field images of the Hubble Space Telescope, the James Webb Space Telescope and others have visually unveiled the abundance of galaxies in the universe. These images are taken with a long exposure time to collect the lightest, so that even very vague objects appear.
Researchers now know that those galaxies are not randomly distributed. Gravity and dark matter pull and guide them to a structure that looks like the web of a spider or a bowl of bubbles. The Rubin Observatory will expand these earlier galactic surveys, which increases the precision of the data and records billions more galaxies.
In addition to helping structure systems throughout the universe, dark matter also disrupts the appearance of galaxies due to an effect that is referred to as gravity lens.
Light travels through the space in a straight line – unless it comes close to something solid. Gravity bends the path of Light, that the way we see it distorts. This gravity lens effect offers instructions that can help astronomers find dark matter. The stronger the gravity, the larger the bend on the path of light.
Discover dark matter
For centuries, astronomers have followed and measured the movements of planets in the solar system. They discovered that all planets followed the path that was predicted by Newton’s movement laws, except Uranus. Astronomers and mathematicians reasoned that if the laws of Newton are true, there must be a missing matter – another massive object – pulls Uranus there. They discovered Neptunus from this hypothesis, who confirmed Newton’s laws.
With the possibility of seeing weaker objects in the 1930s, astronomers began to follow the movements of galaxies.
California Institute of Technology Astronomer Fritz Zwicky came up with the term dark matter in 1933, after observing galaxies in the coma cluster. He calculated the mass of the galaxies based on their speeds, which did not match their mass based on the number of stars he observed.
He suspected that the cluster could contain an invisible, missing matter that prevented the galaxies from flying apart. But for several decades he missed sufficient observational evidence to support his theory.
Enter Vera Rubin
In 1965, Vera Rubin was the first women who were hired to the scientific staff at the Department of Terrestrial Magnetism of the Carnegie Institution in Washington, DC
She worked with Kent Ford, who had built an extremely sensitive spectrographer and wanted to apply it to a scientific research project. Rubin and Ford used the spectrograph to measure how quickly stars around the center of their galaxies.
In the solar system, where most of the masses are in the sun in the middle, the nearest planet, Mercury, moves faster than the furthest planet, Neptune.
“We expected that the further stars and further from the center of their Milky Way, they would bring them lower and slower,” said Rubin in 1992.
What they found in galaxies surprised them. Stars far from the center of the Galaxy moved just as fast as stars closer.
“And that really leads to only two options,” Rubin explained. “Either Newton’s laws don’t hold, and physicists and astronomers are miserably afraid of … (or) stars respond to the gravitational field that we don’t see.”
Data piled up when Rubin Plot created after plot. Her colleagues did not doubt her observations, but the interpretation remained a debate. Many people were reluctant to accept that dark matter was needed to take into account the findings in Rubin’s data.
Rubin continued to study galaxies and measure how quickly stars moved in it. She was not interested in investigating Dark Matter herself, but she continued documenting its effects on the movement of galaxies.
Vera Rubin’s inheritance
Nowadays, more people are aware of Rubin’s observations and contribute to our understanding of dark matter. In 2019, a Congressional Bill was introduced to rename the former large Synoptic Survey Telescope to the Vera C. Rubin Observatory. In June 2025 the American Mint released a quarter with Vera Rubin.
During her career, Rubin continued to collect data about the movements of galaxies. Others continued where she had gone and have contributed to the research of the dark matter in the last 50 years.
In the 1970s, physicist James Peebles and astronomers created Jeremiah Ostriker and Amos Yahil computer simulations of individual galaxies. They concluded, just like Zwicky, that there was not enough visible matter in galaxies to prevent them from flying apart.
They suggested that whatever dark matter it is – whether it is cold stars, black holes or an unknown particle – there could be no less than 10 times the amount of dark matter than ordinary matter in galaxies.
During his 10-year run, the Rubin Observatory should give even more researchers the opportunity to add to our understanding of dark matter.
This article is re -published of the conversation, a non -profit, independent news organization that gives you facts and reliable analysis to help you understand our complex world. It is written by: Samantha Thompson, Smithsonian Institution
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Samantha Thompson does not work for, consults, owns shares or receives financing from a company or organization that would benefit from this article and has not unveiled relevant ties outside their academic appointment.
