A Wellington couple have accepted a slightly less scientific reason for the "space rock" they found in their backyard.

They've had a close encounter with a cunning prankster.

"We were had," admitted Joyce Lockyer, who along with husband Graeme featured prominently in national media for what they reckoned was a meteorite that had slammed into their Wainuiomata garden.

The couple had returned from holiday to find the rock in their backyard, in a small "crater" complete with what appeared to be scorch marks.

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It was first suggested the rock, weighing about 2.4kg, might have been created by debris from Halley's Comet.

But Stardome astronomer Dr Grant Christie had a simpler explanation: "It was a hoax."

Speaking to the Herald this afternoon, Joyce Lockyer said that indeed now appeared to be the case.

"We are now firmly of the opinion that it's a practical joke; there's just quite a few things not tying up," she said.

"So we are not even going to bother having it analysed ... we feel it's somebody's idea of a prank.

"We were had."

Asked if she had an inkling as to the culprit, she said: "Yes I have, and he will pay."

"It's quite embarrassing, but I will get my sense of humour back shortly. It is quite funny when you look back."

Lockyer said media reports had attracted many sceptical observations from people, one who remarked it looked as if someone had simply tossed a rock over the fence.

"If we lived in normal suburbia, I probably would have thought exactly the same ... but we are a long way from our neighbours, which is why we fell for it."

Christie said the story had appeared fishy from the start.

"I don't know why people were getting excited. The whole thing looked contrived."

While the prankster had clearly gone to some lengths to make the "landing site" look plausible by adding scorch marks, Christie said an actual meteorite would have made no such impact.

"Effectively, a meteorite is not coming in at space speed: It's coming in a free fall through the atmosphere, probably only a couple of hundred kilometres an hour, and has cooled off a lot.

"If you fly a good 20kms up and drop a brick, that's about what's going to happen."

While reports of suspected space rocks weren't uncommon - old lumps of iron originating from sunken remains of old clipper ships had resulted in many excited "finds" on the Auckland's West Coast - confirmed meteorites were extremely rare.

So rare, Christie said, that there had only been nine actual cases in New Zealand history, including a meteorite that punched a hole through the roof of the Archer family's Ellerslie, Auckland, home on June 12, 2004.

Yet meteorite-related pranks were also sparse: Christie could recall just one. Some Kohimarama residents whose front window was smashed by "space rocks" that had likely instead been thrown by pranksters from the beach below.

"If they think they've found a meteorite, the first thing people should do contact someone who knows something about it."