Comet 17P/Holmes, an obscure periodic comet discovered in 1892 and not normally visible to the naked eye, exploded on October 23-24, 2007. It brightened by a factor of 500,000 (from magnitude 17 to 2.8) in a couple of days and became easily visible in the early evening sky in the northern hemisphere. At the time of this extraordinary event, the comet was 148 million miles from the earth, farther away than the sun. Wikipedia has a long article about 17P/Holmes and its explosion in 2007.
Below are a few backyard photographs of the comet taken with digital cameras. Paintshop Pro software has been used (1) to add annotations and (2) to reduce the file sizes of the original images (at a small expense in image quality) for faster downloading.
The first picture shows 17P/Holmes as it appeared from Greenville, SC on October 30 at about 8:30 pm local time. It was taken with a tripod-mounted, two-megapixel Canon A60 point-and-shoot camera set for maximum resolution at ISO sensitivity 400. Exposure time was 15 seconds.
The picture was taken with no zoom. The arrow shows the comet in the constellation Perseus.
The next picture was taken with the Canon's 3X optical zoom. The original image has been cropped.
Below is a nice picture from John T in Massachusetts. It was taken November 1 with a Nikon D70 camera using a 200mm lens at f2.8. Exposure time was about 2 seconds.
The picture below was taken from Greenville with the Canon A60 on November 15. The comet is barely visible in this 15-second exposure. In binoculars the comet appeared as a round, very bright fuzzball quite close to α Perseus (Mirfak). Distance to the comet was 152 million miles. Obviously, the cloud of gas and dust had expanded and the comet appeared much larger than it did two weeks before. The total brightness was probably about the same as it was then, but the reflected light is spread over a larger area.
Notice how since October 30 the comet has moved with respect to nearby stars.