The night sky will soon have ‘a new star’. Here’s how to tell.

If you keep a close eye on the night sky in the coming weeks and months, you might discover something new. It will shine as brightly as Polaris, the North Star, for no more than a week before fading into darkness again.

This short-lived lighthouse is often referred to as T Coronae Borealis T CrB. It’s a nova, a nuclear explosion bursting from the pale corpse of a long-dead star. Some people may have seen it before – the same tantalizing spectacle lit up our skies almost 80 years ago – and future generations may see it in another 80 years.

For any world nearby, a nova would be apocalyptic. But for stargazers in our world some 3,000 light-years away, it’s “a fun and exciting upcoming catastrophe,” says Bradley Schaeferan astrophysicist at Louisiana State University.

Here’s everything you need to know about this event: what it is, when it’ll appear, and where you can catch a glimpse of it.

What is a nova?

There are more than 400 known novas in the Milky Way galaxy. They result from the explosive combination between a normal type of star – for example a main sequence furnace like Earth’s sun or a red elephant giant – and a white dwarf, a smoldering star. stellar core left behind after the demise of a star. The two are gravity-bound companions destined to unleash a fiery explosion across the cosmos.

White dwarfs are relatively small, but also so compact that their intense gravitational pull steals hydrogen-rich matter from a nearby ordinary star. That volatile material falls onto the white dwarf’s surface and begins to pile up after a while, crushing the lower layers and raising its temperature.

Eventually, that compressed matter will “exceed the production temperature of hydrogen,” said Dr. Schaefer. It ignites, causing the temperature of the accreted material to rise even further. Beyond a certain point, a runaway nuclear reaction begins, causing an apocalyptic explosion.

“These novae are actually hydrogen bombs,” said Dr. Schaefer.

But don’t confuse a nova with its more violent cousin, the supernova, which permanently destroys a star and angrily sheds its outer layers. After a nova’s nuclear embers are extinguished, the cycle begins again, with the white dwarf once again working its way toward another explosion.

What is T Coronae Borealis and how do we know when it will explode?

T CrB is a nova that forms when a white dwarf peels off enough of the outer layers of a red giant star that is about 74 times the size of our Sun.

The nova last exploded in 1946. Astronomers also observed the outburst in 1866, and historical reports show that it was spotted in 1787 and 1217.

Most novas have explosive cycles that last many millennia. But T CrB is impatient: a voracious consumer of its red giant’s stellar fuel. Past observations indicate that it erupts once every 80 years, making it a recurring nova: one that flares up at least once a century.

Previous observations of T CrB have also shown that the nova flares and convulses in a particularly erratic manner in the years leading up to an eruption, and things appear to be no different this time: activity over the past decade That suggests it’s preparing for an impending explosion, which will happen sometime between now and September.

Where in the night sky can I see it?

T CrB will do that to appear in the constellation Corona Borealis, which is bordered by Hercules and Bootes. When it “blows its pile, it will be as bright as the North star and it will be visible for a few days,” said Bill Cooke, chief of the Meteoroid Environments Office at NASA’s Marshall Space Flight Center in Huntsville, Ala.

“You will notice a new star in the sky,” he added, visible to the naked eye.

Do not miss it. “It’s a one-time event,” said Dr. Cooke. “How many times can people say they’ve seen a star explode?”