Social media websites lit up with people who believed they were seeing a meteor, with some saying the initially thought they were witnessing a plane on fire.

However yesterday morning a number of observatories and astronomers solved the mystery, explaining that it was actually a piece of the Soyuz rocket that was launched on July 8.

Manager of the Dubbo Observatory, Peter Neilson said the relative lack of speed ruled out the possibility it was a meteor.

"According to the Melbourne Observatory, it was a Soyuz rocket piece that was seven metres long and weighed three tonnes. It came in over Melbourne and made its way north. It was travelling at about seven kilometres per second, or 420 kilometres an hour, which is too slow for a meteor," Mr Neilson said.

"A meteor would travel at about 60 or 70 kilometres a second. This rocket has launched and this is a stage that has separated off. It would have entered the atmosphere quite low and that is why it has travelled quite slowly.

"By the time it came over Dubbo it was flashing off bits and disintegrating."

Mr Neilson said careful attention is paid to man-made space junk because of the danger is poses on earth and for anything that is orbited but it isn't unusual for

"The last time we had something like this in Dubbo was the sesquicentenary in 1999. There were fireworks to celebrate the city turning 150 and while the fireworks were going off, we had two or three bits of space junk come in. A lot of people wouldn't have even realised, they would have through it was part of the fireworks," he said.