Around September, a powerful explosion will explode in the night sky 3,000 light-years from Earth, giving amateur astronomers a unique chance to see this cosmic oddity. The binary star system in the constellation Corona Borealis (“northern crown”) is usually too faint to be seen with the naked eye.

But every 80 years, an exchange between two fatally locked stars causes a sudden nuclear explosion. The light from the explosion travels through space, making it appear as if a new star as bright as Polaris has suddenly appeared in the night sky for days, according to NASA.

This will be at least the third time humans have observed this phenomenon, which was first discovered by Irish scientist John Birmingham in 1866 and later resurfaced in 1946. Arizona State University astronomer Sumner Starfield, who received the name, told AFP he was very excited to see the nova “shine”.

After all, he had been studying T Coronae Borealis, also known as the “Flame Star”, continuously since the 1960s. Starfield is now rushing to finish a scientific paper that predicts astronomers will know about the repeating nova as soon as it appears within the next five months.

“I might be like that today… but I hope not,” he said, laughing.

A white dwarf and a red giant

Starrfield explained that there are only about 10 repeating novae in the Milky Way and surrounding galaxies. Normal novae erupt “perhaps every 100,000 years,” he said. But periodic novae keep repeating their explosions in the human timeline due to the special relationship between the two stars.

One is a cold, dying star called a red giant, which is burning its hydrogen and expanding enormously; This is the fate that awaits our own Sun in about five billion years.

The other is the white dwarf, which is the next stage of a star’s death, after all the atmosphere has blown away and only the incredibly dense core remains. The size difference is so large that it takes 227 days for the white dwarf T Coronae Borealis to orbit the red giant, Starrfield said.

They are so close that the material ejected by the red giant collects near the white dwarf’s surface. For a white dwarf to reach Earth’s mass (which takes about 80 years) it becomes hot enough to start an uncontrolled fusion reaction, Starrfield said.

Joachim Krautter, a retired German astronomer who studied the nova, said it “ends with a huge explosion and in a few seconds the temperature rises by 100 to 200 million degrees Celsius.” The James Webb Space Telescope will be just one of many eyes on it when the T Coronae Borealis flare begins, Krautter told AFP. But you don’t need such advanced technology to witness this rare event, whenever it happens.

“You just have to go outside and look in the direction of Corona Borealis,” Krautter said.

A lucky few are already preparing for the biggest astronomical event of the year on Monday, when a rare total solar eclipse will take place in the United States.