As others have already said it is a AP-3C Orion. An apt name for an aircraft being shown on an astronomy forum. It is from No 92 Wing, out of Edinburgh RAAF Base, near Adelaide. Great aircraft! They spend most of there time these days searching for people smugglers and illegal fishing boats. The official term for this is "protecting Australia's Economic Zone"
I can't see the registration from the pic, so can't tell you anything about that individual aircraft. I was based at Edinburgh for 8 years, so if I haven't been on that particular aircraft, it's almost a safe bet that it woke me up in the mornings more than once
BTW great pic!