By ABC NewsAn astronomer says a bright spiralling light spotted in the sky by people across eastern Australia was probably a satellite, space junk or a rocket.
The UFO was seen moving through the sky just before Saturday's sunrise in New South Wales, Queensland and the ACT.
ABC News Online has received dozens of emails, pictures and videos from those who were awe-stricken by the huge white light.
Some described it as a "lollipop-type swirl". Others say it hovered for a while before gradually moving in an eastern direction until it was out of sight. Those who saw the object say photos do not reflect how large it actually was.
Geoffrey Whyatt from the Sydney Observatory says it was probably a satellite, space junk or a rocket.
"The fact that you've got the rotation, the spiral effect, is very reminiscent of the much widely reported sightings from Norway and Russia last year, which both turned out to be a Bulava missile which was being adjusted in its orbit," he said.
"So possibly a rocket, I would say, having some sort of gyroscopic stability rocket fired on its side."
Mr Whyatt says it is a rare phenomenon.
"The first I saw of the spirals was last year when they were reported in Norway and then a few days later in Russia," he said.
"The Norway one was very spectacular because of its symmetrical appearance.
"But the one this morning and the one in Russia bear a striking similarity of being the same effects from a rocket trying to be controlled or adjusted."
A privately-owned rocket launched from Cape Canaveral in Florida on its first test flight is believed to be responsible.
But Doug Moffett from UFO Research NSW says he has a few problems with this theory.
"Firstly, the time of the launch was 18.45 GMT, which translates to 4.45am EST, the duration of the flight was 9 minutes 38 seconds - this is a full hour before the reported sightings," he said.
"Secondly, where was the glow from the boosters or from the friction created by the craft moving through the atmosphere, where was the tail of the rocket?
"Thirdly, why would anyone launch a rocket on a maiden test flight with a trajectory that would take it over the most heavily populated parts of Australia?
"And how big must this rocket have been to be seen so clearly, at the same time, over such a vast distance?"