Snapshot Supernova asks the world’s citizen scientists and armchair astronomers to help discover stars exploding over Australia. It’s the latest project form the Zooniverse crowdsourcing service. The Zooniverse’s co-founder and Oxford University astrophysicist Chris Lintott explained to me how the project evolved from earlier supernova-hunting projects to make its first supernova sighting within hours of the project’s launch.
Burn bright and leave a stellar remnant
In this view from the Hubble Space Telescope, the Crab Nebula is all that remains of a massive supernova that shone in the skies almost a millennia ago. Recorded by astronomers in China and Japan in 1054, it remained visible for two years.
Both the spectrum of that light and the way it fades over time tell astronomers a lot about the nature of the original star and the physical processes inside it. The trick is making the observations as close to the supernova’s beginning as possible. The giant mountaintop telescopes wouldn’t be suited for supernova searches even if they weren’t already heavily oversubscribed by the world’s astronomers.
Dedicated supernova search programs - both professional and amateur - use relatively small telescopes to scan the entire sky over and over again every night. Automated software searches the data for signs of a supernova and flags it for scientists to review before notifying the astronomy community. But sometimes software isn’t that smart.
Amateurs: as good as experts, better than machines
Galaxy Zoo: Supernova was the Zooniverse’s first supernova-spotting project. It used data from the Palomar Transient Factory’s 1.2-meter telescope. The PTF’s software generated 500 supernova candidates every night which a handful of scientists had to review. Only a few of those candidates - and sometimes none of them - would turn out to be supernovae. Hardly a good use of their time. Fortunately, Galaxy Zoo: Supernova’s 13,000 volunteers did the work just as well. They reviewed before-and-after images and flagged those they thought showed a supernova. Thanks to the wisdom of the crowd, the project’s scientists could be confident they had a real supernova when an image got flagged a dozen times. Galaxy Zoo: Supernova’s citizen scientists ended up discovering more than 3,000 supernovae over the project’s two year run.
“Worked” is putting it mildly. The project launched last Wednesday. Within two days more than 36,000 people around the world made over 1.5 million classifications - and discovered their first supernova. As the citizen scientists settle in, the Snapshot Supernova team is helping them improve their work. Lintott explained:
The citizen scientists have time to practice, though. Even with the huge effort of the past two days they are only 8% of the way through. They have a lot more supernovae to spot.
Human and machine - better together
Spotting supernovae isn’t the project’s only goal. The original Galaxy Zoo: Supernova created a massive data set that PTF scientists used to make machine learning search algorithms that can spot supernovae better than any human. Machine learning is a limited form of artificial intelligence. Designed to learn from its own mistakes, the algorithm crunches through a set of known data and rewrites itself as it goes along. As Lintott explained:
That doesn’t mean Snapshot Supernova’s citizen scientists are putting themselves out of a job. The only efficient way to create those spectacularly large training sets is through the combined efforts of tens of thousands of normal everyday people. New survey projects like Pan-Starrs will run into the same challenges with their early software. They will need help from the world’s amateur supernova spotters. Lintott concluded our exchange with this enticing statement:
Want to learn more?
- Read my post about Japanese amateur astronomer Koichi Itagaki, the world’s most prolific individual supernova hunter
- Read the peer-reviewed paper about Galaxy Zoo: Supernova. Written only a few months after it started, the clearly-written paper explains the challenges professional supernova hunters face and how crowdsourced citizen science came to the rescue.
- Check out the Astronomers Telegram officially announcing Snapshot Supernova’s first discovery
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