UH Hilo astronomy alumnus, now at the Catalina Sky Survey, AZ, discovers possible mini-moon orbiting Earth

Research specialist Teddy Pruyne, a 2018 astronomy grad from UH Hilo, and his researcher teammate Kacper Wierzchos discovered the possible mini-moon Feb. 15. Out of about a million known asteroids, this is just the second asteroid known to orbit Earth.

By Susan Enright

Photo of Teddy Pruyne inset into an image of the Catalina Sky Survey
Teddy Pruyne and the Catalina Sky Survey, AZ.

An astronomy alumnus from the University of Hawai‘i at Hilo has made yet another extraordinary discovery from his perch at the Catalina Sky Survey in Tucson, AZ. Research specialist Teddy Pruyne and his teammate Kacper Wierzchos discovered a mini-moon Feb. 15. Wierzchos tweeted about the asteroid discovery on Tuesday.

“BIG NEWS,” Wierzchos, a researcher with the Catalina Sky Survey at the University of Arizona’s Lunar and Planetary Laboratory, explains in a tweet yesterday. “Earth has a new temporarily captured object/Possible mini-moon called 2020 CD3. On the night of Feb. 15, my Catalina Sky Survey teammate Teddy Pruyne and I found a 20th magnitude object.”

“It’s a big deal as out of ~ 1 million known asteroids, this is just the second asteroid known to orbit Earth,” Wierzchos explains in a follow-up tweet. In other words, it didn’t burn up or get ejected as most asteroids do when they come close to Earth. (Learn more about minimoons.)

The object was officially announced by the International Astronomical Union’s Minor Planet Center on Tuesday. The orbit shows that it entered Earth’s orbit some three years ago.

Pruyne earned a bachelor of science in astronomy from UH Hilo in 2018. His task as a research specialist at the Catalina Sky Survey in Arizona is to survey the night sky for objects classified as Near Earth Objects (NEOs).

The mini-moon discovered Feb. 15 is not the first time Pruyne has made news with his observations. On Oct. 31, 2019, he discovered the second closest object on record to graze by Earth and not impact, a close approach that happened only about seven hours after discovery. Additional observations confirmed that the object was not an impact threat to Earth during this passage.

UH Hilo astronomy alumnus discovers second closest object on record to graze by Earth

And there’s more.

In an email describing his work, Pruyne says that on another night, he “also managed to discover a comet: P/2019 X1 (Pruyne).” This discovery is classified as a Jupiter-family comet.

“These are all in addition to finding plenty of NEOs every shift!” he adds.

The Catalina Sky Survey is a NASA funded project with a mission to discover and track near-Earth objects in an effort to meet a congressional mandate to catalog potentially hazardous asteroids which may pose an impact threat to Earth.


Story by Susan Enright, a public information specialist for the Office of the Chancellor and editor of UH Hilo Stories. She received her bachelor of arts in English and certificate in women’s studies from UH Hilo.

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