28/08/2012 20:01 BST | Updated 28/08/2012 20:08 BST

Supernova Surprise: Amateur Astronomer Dave Grennan's Shock At Discovering Two Exploding Stars In Two Years

An amateur astronomer has said he got the shock of his life when he made Ireland's second discovery of a supernova (exploding star) in less than two years.

Dave Grennan was stargazing from his back garden in Raheny, north Dublin when he spotted the 123 million-year-old spectacle in the sky.

"I had the shock of my life. I was about to pack up and go to bed and the very last photo I took I downloaded and I nearly fell off my chair. I couldn't believe it," said the 41-year-old.


The second 'supernova' exploding star discovered by Dave Grennan

"I knew exactly what it was. It wasn't a piece of dust on my camera, it was a supernova."

The software developer, who works for state transport company CIE, discovered the first supernova from Ireland using the same powerful telescope in September 2010.

Mr Grennan said his latest find, on Monday August 22, is a tribute to his hero, moonwalker Neil Armstrong who died on Saturday.


Dave Grennan (left) and his wife Carol in an observatory in their back garden in Raheny, north Dublin

He said he sat up until 4am examining his data and searching records to check if anyone else in the world reported the star, before contacting the International Astronomical Union which formally designated the celestial explosion as 2012ej.


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Experts told him that the star was 100 times bigger than the sun and violently exploded in another galaxy, called IC2166, because it got too big and could not support its own weight.

"It is about 120 million light years away. That means it has taken 120 million years for the light from this explosion to travel the distance across the depths of the universe and reach us here on planet earth," Mr Grennan said.

"So we are looking back in time."

Mr Grennan described his love of the night sky as a vocation, and the support of his wife Carol unwavering.

Four years ago he discovered an asteroid, a minor planet just three metres-wide, and named it after his late mother Catherine Griffin who encouraged his interest in the stars when he was a boy.

The member of Astronomy Ireland and Pete Lawrence from the BBC's Sky at Night will speak at the organisation's star party in Roundwood, Co Wicklow next month.

David Moore, editor of Astronomy Ireland magazine, said a supernova is the biggest explosion in the universe, after the Big Bang.

They can be as luminous as 10 billion suns and the star's matter is propelled into space at around 12,000mph.

"It would be like billions of earths exploding all at once in an unimaginably violent event that would wipe out all life on our planet if it happened to any of the stars near our sun," he said.

"To discover such an event, not to mention two, from Irish soil is a truly remarkable feat."