Southeastern Australia was lit up Thursday night by what was at first taken to be an exceptionally bright meteor. However, multiple lines of evidence suggest it was more likely from a stage of a Russian Soyuz rocket burning up in the atmosphere.

At 9:45pm local time, observers over a 2000km stretch from Tasmania to New South Wales reported  the light, with photos and videos rapidly appearing online. The object broke up near Cobar in central New South Wales.

Such a long flight path is unusual for an extraterrestrial object, but more in keeping with the flatter trajectory of space junk.

Ken Le Marquand, president of the Astronomical Society of Victoria told AAP the object was likely to be artificial, rather than a small asteroid. "The images I've seen show a lot of different colours," Mr Le Marquand told AAP. "When you get lots of colours it usually means there's different materials in there, man-made materials."

Neuroscientist Dr Emma Burrows, who saw the object as it passed over Melbourne said, “It wasn't fast enough to be a meteor. It was like a plane crashing.”

Simon Tiller, a resident of the outer Melbourne suburb of Frankston described the light as turning blue as it approached the horizon estimated the object took 20 seconds before disappearing to the north.

The spacecraft theory was backed up by no lesser source than Nobel Prize winning physicist, Professor Brian Schmidt, who tweeted a link to the trajectory of the rocket that launched seven satellites the day before. 

Burrows was not the only one to think a plane might be in trouble.

The third stage of the Soyuz rocket was 7m long and weighed three tonnes. While NASA estimates a piece of space debris reenters the Earth's atmosphere at least once a day, most are much smaller, and hard to distinguish from meteors. Returning space junk seldom poses a threat to people, and no one has yet been hurt, although the Shire of Esperance sent NASA a bill for cleaning up bits of Skylab that reached the ground. However, orbital debris represents a major and growing threat to satellites.

Alistair Tait of Monash University is part of a team attempting to locate the debris from the rocket. He has asked anyone with images to tag them #AusFireBall, @FireballsSky. Reports, particularly from those who saw it towards the end of its flight path, should be made using an app that can be downloaded from http://www.fireballsinthesky.com.au.

Anyone who might have clues to the landing site should contact Tait on earth-atmosphere-environment@monash.edu.