The Hubble space telescope has photographed a stunning ring of cosmic pearls left by a star that blew itself to bits exactly 20 years ago. Astronomers witnessed the explosion on February 23, 1987. It was the brightest supernova seen for more than 400 years.

Hubble was launched by Nasa three years later and has been monitoring the supernova closely ever since.

The suicide star lies 163,000 light years away in a satellite galaxy of our own Milky Way. That means that the blast happened in 161,000 BC but its light has taken several millennia to get here.

The supernova, called SN 1987A, blazed with the power of 100 million suns for several months. Since then, scientists have watched as light from the star spread outwards and began to light up its surroundings.

The stellar shock wave slammed into, heated up and illuminating a narrow ring of debris that they think surrounded the star at least 20,000 years before it exploded. Today it resembles a pearl necklace and is set to become even brighter over the next few years.

Hubble continues to watch as the blast debris moves through the ring. The light show makes the glowing ring look like a pearl necklace. Astronomers think the whole ring will be illuminated in a few years.

US astronomer Robert Kirshner, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Masschusetts, said: “The Hubble observations have helped us rewrite the textbooks on exploding stars. In fact, without Hubble we wouldn’t even know what to ask.”

Astronomers are still looking for any evidence of a black hole or tiny, super-dense neutron star left behind by the blast. Photo: Nasa/ESA.

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