1. Driving from work through Grafarvogur when it shot down. 2. Just coincidence.3. I had no idea, first idea was a firework but then I remembered it randomly appeared from the sky and went downwards. Plus, no sound or bright "boom" afterwards.4. A clear and bright, green light shot from the sky and headed downwards. It suddenly appeared and then vanished very quickly afterwards.5. I headed towards the light instead of going home, tried to find any sign of what it was. Found nothing.6. It just disappeared quickly after it appeared.