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Queries about a bright light in the southern skies last night have been coming into the Mount St John Observatory.

A reader, Shannon, also saw the light and said: "I'm not 100% sure what it was, but it looked like a comet or something entering through the atmosphere last night around 10.30pm to 11pm.

"It was a bright white light and was moving extremely fast to be a plane, and looked to be breaking up as it moved along, as its colour changed to orange."

Alan Gilmore, a resident superintendent at the Mount St John observatory, said reports from Christchurch described the bright object in the sky shortly after 10pm that was visible for between two to three minutes and left a glowing trail behind it.

"My best guess was that it was a re-entering satellite. A comet does not move like that, it stays more or less fixed against the background stars unless it is very close to the earth, you need to watch it for two or three hours in order to see it moving," Mr Gilmore said.

He said it moved too slowly to be a meteor, which would be gone in two seconds.

"But everything fits with a re-entering satellite, that is a satellite that is heating up because of the friction of the air, probably 100km or higher up in the air, it's glowing white because it's heating up and it's leaving a trail of charged, excited atmosphere gas which glows," said Mr Gilmore.

He said the trail could have also have been smoke picked up by the sun at such a high altitude.

"That's my best guess," he said.