Reports of a bright flashing light in the sky about 11pm were received from Auckland to as far south as Wellington while a sonic boom was heard by many people near Raglan.
Stardome Observatory astronomer and Auckland Astronomical Society president Grant Christie said that was likely caused by a large meteor, or bolide, at least 1m in diameter.
He compared it to another meteor which caused shockwaves and knocked people to the ground when it exploded at a height of 32kms over Wanganui.
GNS Scientists later measured that explosion as having the same force as 350 tonnes of TNT.
"That was more powerful. It knocked people around a bit. But it occurred at daytime. This one would have been more even more dramatic than that because it happened at night."
While the 1999 meteor exploded at a height of 32kms, last night's meteor would have burnt up at a significantly higher altitude, Dr Christie said.
A meteor of that size was only likely to occur in New Zealand once every few years, he said.
Comment: By the look of it, and for quite a while now, these statistical chances are no longer relevant.
He had never seen one in his career and was calling for those who observed it to send in their reports to Stardome Observatory.
Depending on what the meteor was made up of, it could have been anywhere from the size of a handbag to as big as a desk, Carter Observatory programmes officer John Field told NZPA.
"These types of meteors are spotted around the world about once a day and it's just a matter of being in the right place at the right time. It was a lovely clear night last night and it was relatively early, so many people would have seen it."
Eye-witness reports received by the WeatherWatch.co.nz website describe a very bright blue light which lit up the sky.
Can be seen with the help of night vision equipment. Since the night sky is so polluted with lights, night vision equipment will show the shy as it should be seen with the naked eye. I counted several meteors each minute coming from all directions.