Sb: AP 10/27 0122 BRF--Australia-UFO SYDNEY, Australia (AP) -- Orange and red lights streaked across the sky over Sydney early today, sparking a rash of reports of unidentified flying objects. The Daily Mirror, a Sydney newspaper, said that police switchboards were jammed with calls from people claiming to have seen a UFO. But astronomers who watched the lights from the Canberra Mount Stromlo Observatory said they believed the phenomena was caused by space "junk" returning to earth. In a statement, professors Don Mathewson and Vince Ford said that at about 2:30 a.m. they saw a streak of fire move from northwest to southeast parallel to the horizon. "At first we thought it might have been an aircraft on fire but our best guess now is that it was a very large bit of space debris re-entering the earth's atmosphere," they said. Copyright 1987 by the Associated Press. All rights reserved.