File photo: A nova is the sudden brightening of a star, caused by a nuclear reaction on its surface. PHOTO: AFP PHOTO / EUROPEAN SOUTHERN OBSERVATORY

Johannesburg - The day after Nelson Mandela died, a star in the Centaurus constellation flared up – and could be the brightest nova recorded so far this millennium.

A nova is the sudden brightening of a star, caused by a nuclear reaction on its surface.

This one is called Nova Centauri 2013. It’s a classical nova, the result of two stars orbiting each other in a binary system: a dense white dwarf and a larger companion.

If they’re close enough, material from the larger star is pulled on to the white dwarf. The resulting nuclear fusion lights the star up in our skies.

Nova Centauri 2013 was first spotted last Tuesday by John Search in New South Wales, Australia. It was bright enough to be seen with the naked eye then, and only got brighter as the days passed, peaking on Friday.

So far, it appears to be the brightest nova since at least 1999.

A few days later, the Joburg Planetarium says the nova is still bright enough to spot. Head out an hour before sunrise (4am in Gauteng, 4.30am in Cape Town, the Planetarium advises) and look for the Southern Cross. You’ll see Nova Centauri 2013 above and to the left of one of the pointer stars. Take binoculars with you.

But if Nova Centauri 2013 is a memorial for Mandela, then V0603 Aquilae – the brightest nova of the 20th century and, in fact, on record – was his introduction.

“It was discovered in June 1918 when it flared up to the brightness of Sirius, the brightest star in our night skies,” says the Planetarium. “V0603 Aquilae underwent a minor flare, becoming as bright as Nova Centauri 2013, around the time Nelson Mandela was born, 18th July, 1918. May he rest in peace.” - The Star