About 6.30pm Port Macquarie and Camden Haven residents witnessed a large flash of colour tearing across the night sky.

Lighthouse Beach resident David Shannon was fishing on the breakwall at Laurieton when he noticed a significant object in the sky.

"The entire sky lit up as if it was day," Mr Shannon said. "North Brother Mountain turned bright green, and I saw what can only be described as a huge grey mass followed by a firey orange trail streaming across the sky behind the clouds.

"It was moving at about half the speed of a shooting star, literally turning the sky from purple to green to white."

Before, during and after the sighting in this area, local astronomer Dave Reneke was contacted by many people along Australia's eastern seaboard.

"I was receiving calls from people up on the Sunshine Coast in Queensland, all the way through to NSW's Central Coast," Mr Reneke said. "This has created a fair bit of interest, probably because it is a very bright light in the night sky."

Mr Reneke had his own preliminary theory as to the nature of the objects.

"I think it's more than likely to be a fireball," Mr Reneke said. "Fireballs move more slowly than satellites, and are pretty rare. They also give off a smoke trail.

"It's either that, or some king of returning space junk, because there is a lot of stuff floating around up there."

An American observer who was following the social media storm provided an explanation for the object on Friday.

The unnamed observer said that NASA projections showed the decommissioned satellite Molniya 3-53, launched November 21, 1974,had a trajectory right over Australia and was due to crash into the Pacific Ocean off the East Coast on Thursday evening.

If the object was the Molniya 3-53, it follows another Russian satellite that crashed into the Pacific Ocean last year.

The military communications satellite, called Molniya 1-89, fell to Earth April 7, 2012, according to Russia's Ria Novosti news agency.