A rare chance to see two exploding stars is happening in the southern sky

A rare astronomical sight is unfolding in the southern sky. Two exploding stars are shining so brightly that both can be viewed with the naked eye.

It’s hard to predict how long these “fascinating objects” will remain that radiant, but stargazers may have another four to five nights to witness the dual phenomena, says astronomer Juan Luna of the Universidad Nacional de Hurlingham in Buenos Aires.

“The sooner one gets out there to look, the better,” says independent astronomer Stephen O’Meara, who is based in Maun, Botswana. His dig through historical records has turned up just one other instance of an easy-to-see twofer explosion of this type, which occurred for one night in March 2018.

These stellar bursts are considered novas. Unlike star-killing supernovas, the dimmer blasts only affect a star’s outer region. A nova occurs when a dense white dwarf star pulls material from its companion star, which are stuck together in a binary system. The stolen gas accumulates, heating up and building pressure until it explodes and suddenly lights up the sky.

Novas typically reach around 100,000 times the brightness of the sun. They can last for days to months, and about 46 happen per year in the Milky Way — although far fewer are luminous enough and close enough for earthlings to see without special instruments. Luna estimates a naked-eye nova happens once every couple of years.

One of the current novas was first spotted on June 12. Named V462 Lupi, it’s located within the Lupus constellation best seen from the Southern Hemisphere, though some people have reported seeing it from the United States. The eruption reached peak brightness on June 20, and now it’s slowly dimming, Luna says.

In contrast, the second nova, called V572 Velorum, seems to be changing intensity very quickly, he says. It was detected on June 25, reached peak brightness two days later and is in the southern constellation Vela.

While people in the Southern Hemisphere can catch a glimpse of the rare dual explosions without any instruments, telescopes and other equipment may offer a more stunning view. “Both are really fine objects through binoculars,” O’Meara says.