An amateur astronomer has spotted a once-in-a-decade supernova that scientists hope will shed light on how dying massive stars give birth to strange objects such as neutron stars and black holes.

On May 19 seasoned supernova discoverer Koichi Itagaki spotted something strange in a spiral galaxy called M101: a bright new pinprick of light. At about 21 million light-years away from Earth, the new supernova, which is now formally dubbed SN 2023ixf, is the closest such explosion of the past five years and the second closest of the past 10 years, according to NASA.

“It took me about five minutes to confirm that it was a supernova,” says Itagaki, who has claimed 172 supernova discoveries since he picked up the hobby in 2000. “The discovery was made in bad weather with lots of clouds. We were lucky.”

Scientists are thrilled with the finding. Many have spent recent days marshalling every available telescope to witness the celestial fireworks and reveling in the flood of incoming observations. “I was honestly too excited to sleep,” says Yvette Cendes, an astronomer at the Center for Astrophysics | Harvard & Smithsonian, who has already helped arrange multiple studies of the supernova with radio observatories. “Data collection right now is the important thing.”

The excitement stems from what the supernova actually is—and what it is destined to become. This event was a type II supernova, which occurs when a massive star—at least eight times the size of our sun—runs out of fuel. No longer able to withstand the force of its own gravity, the star collapses into a superdense remnant, such as a black hole or a neutron star, blasting debris and radiation into space as it does.

While scientists know the basics of that process, they never turn down more supernova data. “Understanding the deaths of these massive stars has consumed astronomers a good 50, 60 years because this is the gateway to making neutron stars and black holes,” says Shrinivas Kulkarni, an astronomer at the California Institute of Technology and principal investigator of the Zwicky Transient Facility in California, which hunts for supernovae among other short-lived astronomical phenomena.

And SN 2023ixf will be a key addition to astronomers’ roster of supernovae, thanks to the combination of its close location and early detection, which occurred before the supernova had reached its peak brightness and begun to fade. “It’s going to probably be potentially the most detailed supernova studied in terms of the rise and then the decay and all the different stages of the supernova itself,” Cendes says.

In addition, because M101—better known as the Pinwheel Galaxy—is a particularly prized deep-sky object in a patch of the heavens that is popular with amateur astronomers, the odds are good for scientists hoping to track down the now exploded star in preexisting data. “That’s going to really help the model of understanding the story of the star before it died,” Cendes says.

And thanks to the supernova’s close location, astronomers may also be able to gather enough of its light to obtain rainbowlike spectra—wavelength-based breakdowns of its electromagnetic emissions. Because every substance absorbs or emits its own characteristic wavelengths of light, spectra from this supernova will allow researchers to determine what and how much stuff it spit out into its neighborhood. “We’ll be able to look at the elements that are present in the material that’s ejected in the supernova, so that’s really cool,” says Sanjana Curtis, an astrophysicist at the University of Chicago.

A third reason astronomers are particularly excited about the discovery is a cosmic coincidence: it’s the second major supernova to occur in the M101 galaxy in recent years. In 2011 scientists had observed a type Ia supernova, which occurs when a stellar corpse known as a white dwarf steals away so much material from a companion star that the thief becomes unstable and explodes.

“There are two major families of supernovae, type I and type II, and now we have one of each from this galaxy—that’s what struck me as a nice surprise,” Kulkarni says.

Nothing is perfect, however: the new supernova isn’t quite everything scientists would dream of. One day they hope to catch neutrinos—ghostly uncharged particles—and gravitational waves—ripples in the fabric of spacetime—produced by a massive star’s explosion. But they’ll need even better luck than Itagaki had last week: SN 2023ixf was still too far away for existing neutrino and gravitational-wave detectors to score.

M101 appears in the sky near the end of the handle of the Big Dipper, in the constellation Ursa Major. The supernova is now visible with modest backyard telescopes and is expected to remain bright for months.

“Especially if people were observing on the night of the discovery, that’s actually potentially very useful scientific data, and it could potentially even end up in a paper,” Cendes says, noting that observers can submit data from recent nights to the American Association of Variable Star Observers.

“It’s a rare glimpse at a very spectacular and dramatic event that’s happening—in astronomy terms—nearby, and I don’t think people should miss it because it might not happen again for a decade,” Curtis says. “So if you have a telescope, you want to point it at M101 right now.”