Is a nova explosion about to light up the night sky? What to know about T Coronae Borealis

Yahoo

06-05-2025

Any day now, a massive stellar blast could light up the night sky so brightly, you won't even need a telescope to see it.
Sound familiar? In case you're wondering, yes, this is the same so-called nova explosion that astronomers have been patiently waiting for for months.
In June 2024, scientists first alerted the public about T Coronae Borealis, a binary star system that could go nova "any day now." Then one month came and went, followed by another, and another, and another – until ... nothing.
But at last! Excitement has once again been growing after NASA released a May 2025 skywatching guide reminding eager spectators that the distant explosion and its light is still definitely going to reach us here on Earth.
We're still just not sure exactly when.
Here's what we know about T Coronae Borealis, dubbed the "Blaze Star," and why this nova is considered a "once-in-a-lifetime" event.
When can people see a rare nova explosion in 2025? When will we see a star system 'go nova?'
It isn't exactly clear just when stargazers will be able to see T Coronae Borealis go nova, but NASA's guide said it will likely be "in the coming months."
That may seem frustratingly vague, but it turns out, predicting just when the explosion will occur and how long it will take for its resulting light to travel 3,000 light-years to be visible on Earth isn't an exact science.
Astronomers with the Planetary Society had predicted a 70% chance T-Cor would go nova by September 2024 and a 95% chance that it would go off by the end of 2024.
That, of course, didn't happen.
So what's changed? Astronomers recently observed the star dimming suddenly, much as it did right before it last went nova.
A red giant star and white dwarf orbit each other in this animation of a nova similar to T Coronae Borealis.
Will the the bright nova be visible from Earth?
T Coronae Borealis is normally too faint to see without a telescope, but the explosion caused by the nova will be so massive, spectators should be able to look up and see it with the naked eye.
When the event becomes visible on Earth, the nova will be as bright as the North Star, known as Polaris, Preston Dyches, who hosts NASA's "What's Up," a monthly video series that describes what's happening in the night sky, wrote for NASA's skywatching guide.
How to find T Coronae Borealis, the 'Blaze Star,' in the night sky
T Coronae Borealis is located among a horseshoe-shaped curve of stars in the constellation Corona Borealis, or the 'Northern Crown."
Stargazers should have luck spotting it between the two brightest stars in the Northern Hemisphere – Arcturus and Vega – using the Big Dipper's handle to point them to the right part of the sky. This part of the sky should be visible from pretty much anywhere on Earth except for the far south, close to Antarctica, according to the Planetary Society.
The below celestial charts provided by NASA should provide a visual aid:
A sky chart indicating how to locate the constellation Corona Borealis between the bright stars Arcturus and Vega. The Big Dipper's handle points in the direction of Corona Borealis.
Sky chart showing constellation Corona Borealis with the location where nova "T CrB" is predicted to appear. The view depicts the constellation with the nova occurring, indicated by an arrow.
What will the nova look like?
The nova won't look like an explosion, but like a new star that wasn't there before.
For this reason, Dyches recommends that viewers practice looking for it location on a clear, dark night before the nova so they'll be easily able to spot the new addition to the sky when it does become visible.
How long will the nova last?
When the nova finally does occur, it won't stay bright for long, likely flaring in peak brightness for only a few days, according to NASA.
What causes a star to go nova?
In simple terms, a nova event is when energy explodes from a white dwarf star.
But the events can only occur in binary star systems like T Coronae Borealis, which contains a red giant star and a smaller white dwarf star. Because the two stars are gravitationally bound to and in orbit around each other, the white dwarf star – similar in size to Earth but with the mass of the sun – can siphon off the larger star's energy.
Eventually, the fuel on the white dwarf's surface gets hot enough to trigger a thermonuclear explosion – releasing a giant burst of radiation. In fact, the explosions are so powerful, that the Planetary Society compares them to a hydrogen bomb – though the events pose no danger to Earth or even the stars themselves.
Instead, the pattern of build-up and explosion continues to repeat. This differs from a supernova, a one-time event that "completely destroys whatever object triggered it," according to the Planetary Society.
When did T Coronae Borealis last go nova?
About every 80 years, the white dwarf in the T Coronae Borealis binary star system accumulates so much of the red giant star's hydrogen that it ignites a thermonuclear explosion.
That last happened in 1946 and is due to happen again soon.
The red giant star's outer atmosphere is once again "all puffed up," Dyches wrote for NASA, and the dwarf star is close enough that its gravity continually captures some of its hydrogen.
After the impending nova, the event is not predicted again for another 80 years or so.
Eric Lagatta is the Space Connect reporter for the USA TODAY Network. Reach him at [e-mail]
This article originally appeared on Florida Today: Is a nova explosion finally about to happen? NASA says it's likely