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The Dartmouth
July 10, 2025 | Latest Issue
The Dartmouth

Dartmouth researchers help find new planets

Alison Crocker '06 was in the middle of her first night on the job at the Kitt Peak National Observatory in Arizona when she helped discover two extra-solar planets last spring. Crocker, a research assistant to Brian Chaboyer, a professor of physics and astronomy at the College, received a call at four in the morning from another observatory, telling her to stop what she was doing and observe another star.

"I had no idea what to do," she said. "This was my first night with the telescope." Crocker said she woke up her boss, who told her to stop her previous observation.

"I was sort of serendipitously involved in the project," she said.

Crocker -- currently a Rhodes Scholar at Oxford University working on a doctorate in an unrelated field of astronomy -- said she never imagined being a part of the discovery of a new planet.

"It's really neat. Not only discovering a planet, but the first multi-planet system that could be anything like our solar system," she said. "I remember wondering as a kid whether other planets even existed out there at all."

According to Crocker, this is the first discovery of a solar system similar to our own. Nearly 250 extrasolar planets have been discovered by scientists, but most of these planets are much larger than planets in Earth's solar system, but have smaller orbits. These two newly-discovered planets are smaller than Jupiter and Saturn but are comparable in size and orbital distance because their sun is also smaller than our sun.

There was definitely a chance an Earth-like planet was orbiting the sun, Crocker said, but it could not be detected.

Crocker and physics and astronomy professor Brian Chaboyer were part of an international team of 69 researchers, including amateur astronomers, to publish their findings in the Feb. 15 issue of the journal Science.

Chaboyer said in a press release he was grateful for all of Crocker's help.

"Alison was a very quick learner, and I was confident in her abilities," he said in a statement to the Office of Public Affairs. "The 2.4 meter telescope we used is worth about 4 million [dollars]; it is not often that one leaves an undergad in charge of a complex, expensive piece of equipment."

The team discovered the planet through gravitational microlensing, a phenomenon in which one star essentially acts as a giant magnifying glass and amplifies the light of another star passing through its gravitational field. Astronomers can then measure variations in the amplified light to determine if the star contains any planets, and if so, those planets' size and distance from the sun. Two of the six planets discovered so far using gravitational microlensing were analagous to planets in our own solar system, a finding that leads many scientists to believe that Earth-like planets may be more common in our galaxy than had previously been believed.