Aurelion's Orbit seems too small to actually get inside.
One of Aurelions weeknesses is suppoed to be when a Melee get's through his Orbit and Wacks the Stardust out of him.
So when I had Aatrox against him I tried to do that, However I was still hit by his stars in the back. He only had to move very slightly to get me back in his orbit every time I stopped to hit him.
I think i could have avoided his starts by just running with him, but I don't understand how you are supposed to beat him up as melee.