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NOAA - 06/26/2024


Minor G1-class geomagnetic storms are possible on June 28th when a CME is expected to graze Earth's magnetic field. It was launched into space during the early hours of June 25th by an erupting filament of magnetism in the sun's southern hemisphere.

CME - Coronal Mass Ejection


NOAA - 06/26/2024

By the time you finish reading this story, there could be a new star in the night sky. Recurrent nova T CrB (pronounced "tee-core-bore") is poised on the knife edge of a once-in-a-lifetime explosion.

"Our best estimate for the time of eruption is close to now," says Brad Schaefer, Professor Emeritus of Astronomy at Louisiana State University.

Schaefer is a leading expert on T CrB. He's been studying the star since he was a teenager. "When I was 18 years old, I calculated when T CrB should erupt again. The answer was 'around 2026' -- and I've been waiting for this moment ever since," he says.



















Above: A T CrB infographic created by South Korean astronomer Bum-Suk Yeom

T CrB is a "recurrent nova." That means it erupts not just once, but over and over again. Its explosion in 1866 was the first nova anyone had ever seen in detail. "No one knew what caused it," says Schaefer. Another blast in 1946 established its period (79 or 80 years) and led astronomers to the modern interpretation:

T CrB is a binary star system consisting of an ancient red giant circled by a hot white dwarf. Hydrogen from the red giant spills onto the surface of the white dwarf. It takes about 80 years to accumulate a critical mass, then--BOOM--a thermonuclear explosion occurs. "It's an H-bomb that blows up on an incredibly large scale," says Schaefer.

After an explosion, the process resets and repeats. Looking at old light curves, Schaefer realized that T CrB tells us when it's about to explode. Approximately 1.1 years before each blow-up, there's a "pre-eruption dip" in brightness. This dip foretells the next blast.



















Above: The pre-eruption dip in March 2023

Start the clock! "T CrB started its pre-eruption dip in March 2023. If the star behaves in 2023-2024 as it did in 1945-1946, then the next eruption should take place in 2024.4+-0.3," says Schaefer. "That's May 2024 plus or minus a few months."

The explosion will be visible to the naked eye. Schaefer expects it to be about as bright as the North Star. When it blows, T CrB will burst forth as an extra jewel in the "Northern Crown" (the constellation Corona Borealis), easy to find high in the summer night sky between Hercules and Bootes.

"T CrB will be the brightest nova for generations," says Schaefer. "It's a chance for everyone in the world to step outside, look up, and see the hellfire."

Observing tips: (1) Go out tonight to see what Corona Borealis normally looks like: sky map. Then, when the nova explodes, you'll be able to see the difference.

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