In short:
A large, slow-moving fireball has been filmed moving across southern Australian skies on Saturday night.
Social media posts reported seeing what is believed to be space junk over southern New South Wales, Victoria, South Australia and Tasmania.
What's next?
Astronomer David Finlay said footage led him to believe some of the debris may have survived re-entry and will be found on properties in Victoria.
Dozens of people have reported what was believed to be burning space junk moving across southern Australian skies on Saturday night.
Videos and comments have been posted across social media sites from Victoria, New South Wales, South Australia and Tasmania just after 10pm AEDT.
Amateur astronomer David Finlay from Australian Meteor Reports said his Facebook group was flooded with sightings of the slow-moving fireball.
"What we know at this stage from the great vision that we've seen from all these Victorians that have pointed their cameras up at the sky is that it looks like a space junk event, so a piece of human made satellite or spacecraft entering the Earth's atmosphere over Victoria," Mr Finlay said.
Astronomers believe the object spotted in Victoria and New South Wales was burning space junk. (Supplied: Chris Heaysman)
He said the object was particularly slow-moving, which allowed many people to get vision of it as it moved across the sky.
"They've seen it, they've had time to pull their phones out of their pockets and point it up at the sky and start videoing.
"This thing was still blazing across the sky. That in itself tells us that it was a space junk event.
"Meteors and space rocks, they travel far too quickly. They only last a second or two."
Nathan Gervasi walked into his yard at Lake Boga near Swan Hill, in Victoria's far north-west, late on Saturday night to turn off the sprinklers on his front lawn.
He looked across the lake and saw a bright light in the sky.
"I'm like 'that's not a plane because that's not blinking, what's going on here?' and then it just kept getting seemingly closer," Mr Gervasi said.
He said he had more than enough time to pull out his phone and start recording.
"It was the biggest and longest burning one that I've seen. It was amazing."
Camper Chris Heaysman spotted the fireball at Lake Mungo, in south-west New South Wales. (Supplied: Chris Heaysman)
Camper Chris Heaysman was camping at Lake Mungo, in south-west New South Wales, when he "saw a big thing shooting through the sky" towards the north.
"It look like a big fire ball. I wasn't worried about it, just amazed and wondering what it was."
David Finlay said the footage he has viewed led him to believe the debris did not fully burn up before hitting the ground.
"Don't be surprised if, in the next week or two, we get a report from some farmer out in the highlands of Victoria and they've actually found bits of strange stuff out on their farm," he said.
"We've had that before with SpaceX spacecraft, we've had bits of that found over Australia a few years ago, and I wouldn't be surprised if the same thing happens in this case as well."
The Australian Space Agency confirmed it was investigating the alleged sightings.Â
"The Australian Space Agency is enquiring into reports of flashes of light in the sky over parts of Eastern Australia," a spokesperson said.
"The Agency is not aware of any planned space debris re-entries that may be associated with these sightings."
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Mr Finlay said his team of astronomers were still viewing all the footage and looking into its origin.
He said the space junk was not debris from a Russian rocket that was predicted to re-enter the atmosphere over international waters south-east of Tasmania between March 3 and 7.
He said that had already been documented.
"We haven't figured out what this was last night and who owned this piece of space junk.
"People and governments need to be informing each other as to when they think that these things are going to come down and exactly where they might come down."
He said there must be better regulation of the space industry, including obligations to communicate about re-entries and possible debris.
"One thing about space junk is most of it is supposed to end up in what we call the Pacific graveyard.
Mr Finlay said the "Pacific Ocean is so big, it's a fantastic target to de-orbit things into".
"Where they start entering the Earth's atmosphere can be over Australia and if their trajectory is slightly out, we can sometimes be in the targeting line, which we we seem to have been for this object last night."
Geoscience Australia said it did not record any seismic activity sometimes associated with space junk re-entry.Â