Science · Breakthrough
The security researcher who built his own sky-searching tools, then found a world that glows
Dan Caselden, Paul Westin, Adam Schneider · Massachusetts, USA
Dan Caselden looks for cold, starless worlds in his spare time. The one he found turned out to be glowing, and when the team reported it in January 2024 the cause was still an open question.
The person and the place
By day, Dan Caselden is a computer security researcher. In his own hours he is a citizen scientist with Backyard Worlds: Planet 9, a NASA-funded project that invites anyone at all to comb through spacecraft data for brown dwarfs, the objects too large to be planets and too small to be stars.
The problem Dan cared about
Brown dwarfs are cold, faint, and very good at hiding. Volunteers work through image after image by eye, because a thing that moved is still something the human eye catches best. "They're really hard to find," Caselden says. "It's the needle in the haystack problem, which is so much fun."
The agency moment
He did not just click through the images he was handed. With his colleague Paul Westin he built WiseView, which animates the survey images so that anything moving gives itself away, and he went on to write machine learning code for the search. Astronomer Adam Schneider used WiseView to confirm that an object he had noticed years earlier was moving fast.
What changed, with evidence
Through the project, Caselden found W1935, bigger than Jupiter, too small to be a star, drifting with no sun of its own. When Jackie Faherty's team pointed the James Webb Space Telescope at it, the methane in its atmosphere was not absorbing light the way everyone expected. It was glowing, the signature of an aurora, on an object with no star to spark one. Faherty: "We expected to see methane because methane is all over these brown dwarfs. But instead of absorbing light, we saw just the opposite: The methane was glowing." When the team reported it in January 2024, the cause was still open. Their own candidates were an internal process, interstellar plasma, or an unseen active moon, and none was confirmed.
Where it led
Caselden is now a co-investigator on a Webb observing campaign studying these cold worlds. Curiosity was the whole qualification; he brought the tools.
The move worth copying
Curiosity was the entire qualification; he brought the tools himself. Backyard Worlds is still open, and the next cold world in the data is waiting for whoever is patient enough to notice it.
"It's chock full of really hard problems. And if you make any improvement, it's felt by the science team. You can see that what you do has an actual impact." — Dan Caselden, Discover Magazine
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