He must have re-pointed the camera between exposures of the moon. In the article, he says that because of a camera malfunction, he had to capture a shorter interval than originally intended. He did this without changing the template he had put into the camera's viewfinder.

https://www.timeanddate.com/eclipse/in/australia/sydney?iso=... has the direction and altitude for the moon as viewed from Sydney during the eclipse. I suspect that if plotted out, they'd trace out something pretty close to a straight line.