On Wednesday, October 24 2007, Comet Holmes (17P) suddenly brightened from something visible only with fairly powerful telescopes (17th magnitude) to something easily visible (2nd Magnitude) from downtown Atlanta.
The way the magnitude scale works, lower numbers are brighter, and every five magnitudes corresponds to 100x in brightness. Thus, Comet Holmes became 15 magnitudes brighter, or 1003 (1,000,000) times brighter... and brighter yet over the next few days.
This picture was taken on October 26th, from the middle of Atlanta, Georgia, at 8:33 PM, facing northeast. It is a 15 second exposure on a Canon Powershot A75, the middle cut out and scaled to a more reasonable viewing size. Click to see the original image.
The distance from Mirfak (the brightest star in Perseus) to Comet Holmes was about two thumb-widths held at arms' length.
This image was taken with the camera's 3x zoom. The comet looks slightly yellow. I'm not sure if it's just my camera or if I'm really picking up the color. There is no comet tail; note that all the stars in this image are slightly streaked.