Astronomers Discover New Potential Dwarf Planet

It’s not every day that scientists get to say they have discovered a new planet in our solar system, but that day arrived this past July for Masao Sako, an associate professor of physics and astronomy, and Gary Bernstein, the Reese W. Flower Professor of Astronomy and Astrophysics.

Along with colleagues from the University of Michigan, Fermilab, and five Penn undergraduate students, the researchers found a dwarf planet candidate—called 2014 UZ224 and nicknamed DeeDee—around 8.6 billion miles from the sun. The planet is currently three times as far from the sun as Neptune and the second-farthest object (with a known orbit) in the solar system after dwarf planet Eris, which is 8.9 billion miles from the sun.

The discovery was a happy accident, what Bernstein calls a “fringe benefit” of the Dark Energy Survey, a project that has so far resulted in 44,000 highly detailed images of the sky. The investigation initially aimed to confirm dark energy as one way to explain the acceleration of the universe’s expansion. But pictures of large swaths of sky are bound to reveal other hidden treasures.

“Stars are always in the same arrangement; they are fixed,” Bernstein explains. But, he says, “something moving around the sun will appear to move among the stars.” If an individual were to compare two images of the sky weeks or even years apart and found an object in one but not the other, more than likely it’s not a star.

Sako adapted some of the survey’s software to essentially subtract one image’s content from another, giving the researchers a list of dots to examine further.

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