In short here is an image showing the ring of fire around Venus - when light from the sun interacts with Venus's atmosphere, illuminating it from our perspective on Earth.
Location: Fort Collins, Co Date: 2012-04-23 Camera: Canon XSi (modified) Lens: Canon 200mm f/2.8 Shot: Mosaic (5-panel) 5x5 seconds f/4 ISO 400 Processing: Photoshop, Topaz
Location: Fort Collins, Co Date: 2012-04-23 Camera: Canon XSi (modified) Lens: Canon 200mm f/2.8 Shot: Single Shot 1x1.3 seconds f/2.8 ISO 800 Processing: Photoshop, Topaz