Some mysterious and oddly shaped orbs in the sky have left Australians wondering if they had spotted a UFO.

Three glowing white shapes were seen pulsating and expanding above the east coast around midnight on Wednesday.

WATCH THE VIDEO ABOVE: East Coast UFO sighting.

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Residents from Queensland to northern NSW posted videos of the eerie sight on social media, with many speculating they had just caught a glimpse of something not of this world.

“Maybe three UFOs or a big star ship,” a Gold Coast witness told 7NEWS.

“The one my brother witnessed ... woke him up because it was so bright,” said another viewer.

“I think it might be something terrestrial from outer space,” one person guessed.

“Probably asteroids,” another suggested.

“It’s a UFO. It has to be,” another viewer insisted.

While the glowing orbs sparked talk of extraterrestrial visitors, Australian National University astrophysicist and cosmologist Dr Brad Tucker offered a more down-to-earth explanation.

He told The Morning Show the mysterious sight was actually a rocket plume — the exhaust released when parts of a rocket separate during launch.

But the plume did not come from the first-ever Australian-made rocket that crashed 14 seconds after launching on Wednesday.

“This was from a Chinese launch, a Chinese Long March 8A, launched about 6.15pm AEST. So, it really matches up with the program,” Tucker said.

According to Chinese media, the rocket lifted off from the Hainan commercial spaceport at 5.49pm on Wednesday AEST, carrying the sixth batch of low-orbit internet satellites into their planned orbits.

The launch was reported as a complete success.

Tucker said the rocket was launched to the southeast, passing over the ocean just off the coast of Queensland.

“Rockets have multiple stages, and when those parts of the rocket separate, they have little thrusters and gas that separate them. And that’s kind of the exhaust coming out,” he explained.

“So, you can kind of picture there are two sides in the photo you’re seeing now.

“That’s the gas coming out the side as the rocket separates.”

The unusual shape of the orbs is not unheard of.

“Sometimes we call these ‘space jellyfish’, believe it or not, because of the weird shape and tentacles,” he said.

Although the lights may have seemed close, Tucker said they were likely hundreds of kilometres offshore and dozens of kilometres in the atmosphere.

“If you think about the rocket launch as it goes up, it actually takes quite a while to actually enter space.

“And so it’s traveling for hundreds, if not thousands of kilometres before those parts are separate.

“They’re also designed that when they separate they separate over the ocean so that if obviously anything comes down it lands in the ocean.”

As for why the orbs appeared to be floating in place, he said it was simply the lingering exhaust hanging high in the atmosphere.

“It’s kind of like peeling out in a car — the dust plume just hangs in the air behind it,” he said.

“The same thing happens with a rocket.”

The strange sight, he added, will eventually fade.

“The gas stays where the separation happens, and over time it just fades off into the atmosphere.”