NZ's meteor light show: Your chances of finding space souvenir

The chances of anyone finding the meteor that lit up New Zealand skies last night are remote.

Stardome astronomer Dr Grant Christie said this morning it was unlikely any remains of space rock would be found in New Zealand, as its trajectory had likely ended hundreds of kilometres east of the country.

In New Zealand, only nine found objects have ever been confirmed as having come from space.

'Almost certainly extra terrestrial' - Meteor lights up night sky

"It's extremely improbable that you'll actually find one, but of course we'd be very excited if we found a 10th or 11th one," he said.

"In this case, the final detonation was seen way off over the ocean - maybe 200km east of Auckland by the look of the MetService image."

Dr Christie said it was easy for people to believe the meteorite had come down on land.

"It might look like it has landed just across the hill from where you are, or maybe in somebody's backyard - but in fact it's hundreds of kilometres beyond that - and the reason is these things are travelling so fast, in the order of 20km per second.

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"So that's 20 times faster than a bullet - and in the five seconds you are seeing it streaking across the sky, it's already covered 200km - people's brains simply don't register that dimension."

It was also false to compare a meteorite to fireworks coming down - "it's much, much brighter than that" - or to make assumptions on its closeness based on its sound.

That some observers reported a time lag of five minutes after seeing the object gave some indication of its distance.

The flash in #Auckland tonight was definitely not lightning, most likely a #meteor #nzmeteor MetService image pic.twitter.com/FU2dHzEBhl

— Auckland CDEM (@AucklandCDEM) February 11, 2015

"Assuming sound is travelling roughly at a kilometre per second, the detonation was 300km away and it took the sound that long to arrive."

Dr Christie said such events happened as regularly as once a day somewhere on Earth.

"The earth is running into these things all the time - it's just that we can only see a small part of the planet from New Zealand, and therefore our chances of seeing one are reduced."

He said the last comparable event in New Zealand was on July 7, 1999, when a meteorite detonated over southern Taranaki with an equivalent energy release of 300 tonnes of exploding TNT.

That blast was powerful enough to force one Waverley farmer hard down on his farm bike - but Dr Christie said last night's event probably only packed the power of tens of tonnes of TNT.

Dr Christie agreed it was a "bolide" that had been knocked off an asteroid millions or billions of years ago.

"These fragments are circulating in the solar system and occasionally they drift into the path of the Earth - but without having a piece of it, you can't really say which asteroid it got broken off."

About 45,000 meteorites have been recorded over Earth, of which just over 1100 have been seen falling.