An object which exploded in the sky over the lower South Island on Tuesday night is believed to have been space junk.
Sightings of the rare display, which lasted about two minutes, were reported all over Otago.
Dunedin man Hayden Ferguson was having a beer after work on his lawn when he spotted it.
"I looked up into the sky and saw this big bright light, so I ran and got my phone, took a video and I couldn't believe it," says Mr Ferguson.
"It was bigger than a plane, it was huge. I've never seen anything like it. It lasted for a good two minutes, I'd say. It was just like a rainbow, starting at one end [of the sky] and streaking over to the other."
Initially thought to have been a meteor, astronomers say it's likely the fireball was debris from the International Space Station.
"Everybody agrees that it was something orbiting the Earth that was burning up as it came back into the atmosphere," says astronomer Alan Gilmore.
"It might have been the first stage of a supply rocket to the International Space Station. Apparently one was launched just a few days ago. Another astronomer suggested it was another bit of rocket that was launched many years ago."
The long length of time the fireball was visible rules out the possibility it's a meteor, which would only be visible for a few seconds, says Mr Gilmore, but there has been no official confirmation of what it was.
"Presumably space authorities who track all this stuff would know exactly what it was, but I don't have access to those sort of databases."
Mr Gilmore says the fireball was completely safe and the thrill of seeing it is a very rare one indeed.
"I only know of one other case in New Zealand of a definite sighting of something like that coming in and that was about 10 years ago," says Mr Gilmore.
"An individual has almost about zero chance of seeing one. But I guess globally they must be fairly frequent given the amount of stuff out there."We don't yet have confirmation on what the unidentified flying object was, but we do know the truth is out there.