Backyard astronomer discovers supernova

The signs of the major celestial event, a colossal detonation, flashed across the universe for millions of years before reaching the first person on earth to become aware of it: a man in a shed in Dublin.

The achievement of an amateur star-watcher in spotting a supernova, one of the most dramatic events of the heavens, has been hailed as "the biggest thing ever discovered in Irish astronomy". A supernova is a cataclysmic explosion during which a star self-destructs with such force it destroys nearby suns and planets. They are spotted reasonably frequently from Earth, but this is the first ever identified from Ireland. Dave Grennan, a 39-year-old software developer who is a committed watcher of the skies, devotes many hours to astronomy.

He said it was "mind-boggling" to be the first person to witness something which happened in the time of the dinosaurs. "We are watching an event as it is unfolding, yet that event happened nearly 300 million years ago," he said. The time-lag is on a scale almost as difficult to comprehend as Ireland's astronomical debt. The far-away star has been designated "2010ik" after its supernova status was confirmed this week by international astronomy bodies.

Mr Grennan said: "I was going to wrap things up and go to bed, and then I thought, 'Dave, you don't make discoveries in bed – at least not those sort of discoveries'." He said his wife, Carol, was "more excited about this discovery than I was", adding with a certain inevitability: "She was over the moon." A former chairman of Astronomy Ireland, Mr Grennan made his discovery while poring over photographs he had taken of a galaxy called UGC 112 from his compact but well-equipped backyard observatory. The signs were tiny but his long experience helped him spot them – he has been interested in astronomy since he was a boy.

He has examined thousands of galaxies over the past decade, and in recent years has also identified two asteroids. "I find myself wondering if there were some poor souls living on planets surrounding the star when it exploded," he said. "We'll never know."

David Moore, chairman of Astronomy Ireland, said it was an unusual supernova which would interest scientists worldwide. "We could not find words to explain it, I've been waiting for this to happen for decades," he said.

The star will be visible through powerful telescopes for up to three months.