People across New South Wales, Queensland and the ACT say they were startled this morning by a huge white light moving across the sky.

Canberra resident James Butcher says he was driving home from a night out with his brother when they spotted the "strange spiral light in the sky".

"It had a distinct bright centre, much like a bright star, indicating an object shedding light trails, spiralling and fattening out from it," he said.

"The effect lasted only two or three minutes, moving and descending quickly out of view.

"The colour was yellowish but this may have been blurred and tinted by the morning fog."

Wollongong man Eddie Wise says he also saw the light during his morning walk just before 6:00am.

He says he has never seen anything like it.

"It was like a yellowish, greenish light with a light spiral around it," he said.

"It sort of moved around, bobbed up and down and then it went behind a cloud.

"I'm just amazed. I want to know what it was."

A caller to the ABC, Robyn, says she saw the phenomenon from her home on Sydney's north shore just before 6:00am.

She says it was over within two minutes.

"There was this white light up in the sky like a huge revolving moon," Robyn said.

"At first I thought it was the moon but it was travelling so fast, high up above the eastern horizon and twirling as it went.

"It was just amazing and to be quite frank, I was quite frightened and my heart's still pounding."

Queensland sightings

A number of people from Morayfield and Caboolture in Queensland have reported that they too saw a white light in the sky about 5:50am.

"It was just the one light. I just came home from my walk and I happened to look up in the sky, and here it was racing across the sky," Linda told 612 ABC Brisbane.

"I bashed on the window for my husband to have a look and he flew out.

"It was spectacular."

Linda described the light as like a lollipop swirl.

She says the light came from the west and was headed east, out to sea.

"It was just unreal. There was a cloud in the sky - just this light with a swirl in the middle," she said.

Peter, from Balmoral, says he saw the light while he was on a ferry terminal on the Brisbane River.

"It certainly had that lollipop-type swirl ... but it was travelling low and fairly fast, and as it went past me and I looked up, it looked like a row of lights, maybe four lights," he said.

Denise, at Pine Mountain, told ABC radio in Brisbane that she saw the lights shortly before 6:00am.

"I got up at about 5:45 to let my horse out of his stable ... and I saw this coming from a north-west direction towards the south-east," she said.

"There was no noise. It was like bands of ribbon coming out of it and it looked like it was coming through a cloud, yet there were no clouds."

An astronomer says space junk or meteors are the most likely explanations for the UFO sightings.