A 'new' star will light up the sky soon and you can see it for yourself

Star light, star bright, will there be a new star tonight?

That's the question astronomers are waiting to answer, as they await a spectacular stellar explosion they believe is on the horizon.

To be clear, the star already exists, but it's invisible to the unaided eye — for now.

Roughly 3,000 light years away is a binary star system in the constellation Corona Borealis. As its name suggests, a binary star system consists of two stars. In this case, one is a large red giant star, and the other is a small, but incredibly dense white dwarf.

As they orbit each other, the red giant's material gets sloughed off and falls into the white dwarf where it accumulates and heats up. The white dwarf then experiences a thermonuclear explosion — a nova — brightening to a point where we can see it with the unaided eye on Earth. 

(Interestingly, our own sun will eventually become both a red giant and a white dwarf as it nears the end of its life. First it will swell, shedding its outer layers (and yes, destroying all life on Earth), and then become compact and super dense, around the size of Earth.)

In order to get a sense of  just how bright T Cor Bor (as it's known, for short) will get, you need to know how astronomers measure brightness. It's on a magnitude scale, where — counter-intuitively — the lower the number, the brighter the object. 

T Cor Bor normally shines at a magnitude of 10. However, it's believed that it will shine as bright as a second-magnitude star.

When a star changes brightness over time, astronomers call it a variable star. This particular type of variable star is called a recurrent nova. 

But the big question that hangs in the air is: when? When will T Cor Bor experience that magnificent explosion?

T Cor Bor was discovered by astronomer John Birmingham in western Ireland when it went nova in 1866.

Before that no one understood what caused the periodic brightening and fading of some stars. 

But the nova occurred again 80 years later, in 1946. Going backward, Brad Schaefer, an astronomer and professor emeritus at Louisiana State University who's been studying T Cor Bor for decades, recently noted a long-lost account of a brightening in the same location in 1787, which suggested that T Cor Bor is a recurrent nova with a period of 79 to 80 years.

Though there have been few eyewitness accounts, Schaefer's work from the 1945-47 data shows a rapid drop in the star's brightness just before the eruption. This is where we are at the moment, leading Schaefer and others to believe we're heading for a rapid brightening any time between now and September.