half disc like shape with a pale green glow that had movement I've never seen before.I didn't really think about reporting this at first but I decided why not maybe someone else saw it too. I didn't know where to begin with that anyway.I was driving north on highway 218 when I was approaching a stop light. I noticed a light, which I thought was an airplane, in the sky to the east. It was in the blue, sun-blocking part of the windshield so it just looked like a light.When I hit the stop light I ducked my head for a better view. I noticed there was a pale green light around whatever it was and it was shaped like a half circle, but not quite. The end of each side stretched a little further back. The thing itself was a dark color I couldn't make out anything on it because it was night. This was also when I noticed the thing wasn't moving. I turned off the radio and before I could really think the thing took took off heading north east. It moved like nothing I have ever seen before and I don't really know how to explain it. I just glided off and it didn't even seem like it accelerated. It was like it was just at full speed but there was no jerking effect. The green color traced behind it a bit and the thing was gone within a couple seconds.I was looking around at other cars to see if they saw. I wanted to get out and ask if anyone saw that but the light turned green and I pushed this to the back of my mind basically. Nothing you can really do about it.