Neutrinos Are Worth a Thousand Words!
The expected rate of Galactic supernova is approximately 2–3 explosions per century, which averages out to about one supernova every 30 to 50 years.
The last confirmed naked-eye Galactic supernova was Kepler’s Supernova in 1604.
However, these stellar collapses often lead to the birth of a neutron star which emits most of its gravitational binding energy in weakly-interacting particles, called neutrinos.
This binding energy scales as the square of the mass of the neutron star divided by its radius.
Neutrinos Are Worth a Thousand Words! Avi Loeb 7 min read · Just now Just now -- Listen Share
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We are due to witness a new stellar explosion in the disk of our Milky-Way galaxy. The expected rate of Galactic supernova is approximately 2–3 explosions per century, which averages out to about one supernova every 30 to 50 years. The last confirmed naked-eye Galactic supernova was Kepler’s Supernova in 1604. Cassiopeia A exploded at around 1680 but was not recorded, likely because it was obscured by dust.
Press enter or click to view image in full size (Image credit: Greg Wyatt)
The main obstacle in discovering an optically-bright supernova is extinction by interstellar dust. Massive progenitor stars have a short lifespan and are born in dense molecular clouds where the column of dust is higher than average, hiding the optical flare from the explosion. However, these stellar collapses often lead to the birth of a neutron star which emits most of its gravitational binding energy in weakly-interacting particles, called neutrinos. These neutrinos are not attenuated by interstellar dust, and their detection offers a better tool for discovering obscured Galactic supernovae.
The first detection of supernova neutrinos took place for Supernova 1987A, which exploded in a satellite galaxy, the Large Magellanic Cloud, located in the halo of the Milky-Way halo at a distance of about 168,000 light years. The neutrinos, detected when I started my post-graduate career 39 years ago, were the subject of my first paper in astrophysics (posted here).
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On February 23, 1987, a total of 24 neutrinos — primarily of the electron flavor — were reported worldwide from Supernova 1987A. A brief 13-second burst was discovered simultaneously by three underground detectors: Kamiokande II (Japan) — which detected 11 neutrinos; Irvine-Michigan-Brookhaven (USA) — which detected 8 neutrinos; and the Baksan Observatory (Russia) — which detected 5 neutrinos. Our paper inferred the total energy released, the cooling time, the effective surface temperature and radius of the newly-born neutron star, and also derived an upper limit on the electron neutrino mass based on the spread in arrival times of neutrinos with different energies.
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The detection prospects today benefit from two separate boosts: bigger detector mass and potentially a shorter distance. A typical Galactic supernova in the Milky-Way disk would be much closer than the Large Magellanic Cloud, increasing the neutrino flux inversely with the square of the smaller distance. Super-Kamiokande (Super-K) currently employs roughly ten times the fiducial tank volume of Kamiokande-II. For a core-collapse supernova at the distance of the Galactic center, Super-K is expected to record on the order of 10,000 events, compared to Kamiokande-II’s 11 neutrinos. In addition, the Jiangmen Underground Neutrino Observatory (JUNO) in China completed construction in August 2025 and is expected to record several thousand events for such a Galactic supernova with excellent energy resolution that Cherenkov detectors like Super-K cannot match. IceCube (South Pole) does not resolve individual neutrino interactions the way Super-K does, but instead detects a collective rise in photomultiplier noise rate across its entire array of over 5,000 optical sensors buried in a cubic kilometer of ice. For a Galactic supernova, IceCube would register this collective excess with overwhelming statistical significance within seconds. Hyper-Kamiokande (Japan) is expected to be complete in 2026, with data-taking starting the following year. It has more than 8 times the tank volume of Super-K’s, implying that once operational, it alone could detect tens of thousands of events from a Galactic supernova. Finally, DUNE (USA) uses liquid argon rather than water — a different detection channel entirely, primarily sensitive to electron-neutrinos (versus the electron-antineutrino sensitivity of water/scintillator detectors), which makes it scientifically complementary to the other detectors. DUNE’s far detector modules are being filled and commissioned through 2026–2027.
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What could we learn from a discovery of a future Galactic supernova by these neutrino observatories?
The time spread among neutrinos of different energies can be used to measure or constrain the neutrino masses. Given the distance of the supernova, the total fluence can be used to measure the energy released, which translates to the gravitational binding energy of the neutron star. This binding energy scales as the square of the mass of the neutron star divided by its radius. A measurement of the characteristic emission temperature constrains the gravitational potential of the neutron star, which scales as its mass divided by its radius. With both quantities measured, one can derive both the mass and the radius of the hot neutron star.
Neutrinos come in three known flavors: electron, mu and tau. The time-dependent energy distribution of detected neutrinos of different flavors can constrain fundamental parameters of nuclear physics as well as neutrino oscillations which would constrain the masses and mixing angles of the three neutrino species.
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Did the neutron star in Supernova 1987A collapse to a black hole?
No. The Webb telescope detected emission from a neutron star at the site of Supernova 1987A in July 2022, just after the telescope began its science operations. The data exhibited an excess of emission in the central pixels of the supernova ejecta, indicating ionized argon as a signature of a newborn neutron star (as reported here). A follow-up paper published here, reported Webb data on the inner ejecta and revealed a velocity shift in the emission lines as evidence for a natal kick that the neutron star may have acquired as a result of an asymmetric collapse.
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In this essay, I featured seven amazing watercolors from a series created by the celebrated artist, Greg Wyatt. They include insights from Marla Celeste and Galileo Galilei. This is the 23rd in a sequence of essays, where Greg and I collaborate on the interface between art and science. The first essay in this series, titled “Music of the Cosmic Spheres,” appeared here; the second essay, titled: “Cosmic Waterfalls in Spacetime Cliffs,” appeared here; the third titled “Missing Elements in the Cosmic Jigsaw Puzzle,” appeared here; the fourth essay, titled: “Why Do We Exist?”, appeared here, and the fifth titled “Inspiration from the Stars”, appeared here, the sixth titled: “We Might Understand How the Cosmos Works Before We Understand How Life Works”, appeared here, the seventh titled: “Will the Human Survive for Billions of Years”, appeared here, the eighth titled: “The Butterfly Effect of Intelligence in the Cosmos”, appeared here, the ninth titled: “Benefits of Extraterrestrial Intelligence over AI”, appeared here, the tenth titled: “Übermenschen on Exoplanets” appeared here, the 11th titled: “If You Had an Infinite Research Budget, How Would You Allocate It?” appeared here, the 12th titled: “Are Human-Made Objects Orbiting Earth?” appeared here, the 13th titled: “Lets Send AI Astronauts, Not Humans, to the Moon”, appeared here, the 14th titled: “Our Highest Priority Should be National Innovation Centers to Complement AI Data Centers” appeared here, the 15th titled “The Cosmic Shells That Seeded Life” appeared here, the 16th titled “Chasing Alien Mysteries in the Sky” appeared here, the 18th titled: “The Smartest Investments in Our Future Are in Space” appeared here, the 19th titled: “The Best and Worst Are Yet to Come”, appeared here, the 20th titled “Would Alien Visitors Possess Intelligence Based on Silicon Chips or Synthetic Biology?” appeared here, the 21st titled “Cosmic Discoveries by National Security Sensors” appeared here, and the 22nd titled “On Mysterious Orbs and Fireballs” appeared here.
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ABOUT THE AUTHOR
Press enter or click to view image in full size (Image Credit: Lotem Loeb, May 22, 2026)
Avi Loeb is chair of the UAP Science Advisory Council to the White House, Pentagon, FBI and intelligence agencies, director of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, former director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
Professional website:
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