Back in 2007 astronomers were excited by a comet known as 17P/Holmes. What was so exciting was that the seemingly ordinary visitor from distant parts of the Solar System suddenly put on a great show. In October, the usually dim 17P/Holmes changed from an unremarkable telescopic object to become visible to the unaided eye, appearing as a yellow “star” in constellation Perseus. It was briefly the largest object in the Solar System. The outburst was believed to be similar to one that took place in 1892 making it visible to amateur astronomer Edwin Holmes, credited with its discovery on November 6 of that year. The reason for the sudden brightening or outbursts remains unknown.
I used my little Canon Rebel XT digital camera attached to the vintage Cooley Telescope at Stephens and attempted to capture images of the comet. The effort and the camera were pretty primitive compared with what we can do now but I got some images and they were the best I could manage at the time. Comet 17P/Holmes faded from visibility over the next several weeks. The somewhat odd appearance of the comet — no classic head and tail — is the result of our perspective: looking straight down its tail instead of from the side.
Recently I viewed a television show about comets and the strange behavior of 17P/Holmes was discussed. That program reminded me of the 2007 apparition and to look at my old images. There wasn’t much image data to work with but I reprocessed what I have and produced a new image a bit better than my first try; that image, shot through our old telescope, appears above.
The “P” in the comet’s designation stands for periodic, meaning after a period of time 17P will return to loop, once again, around Sun. In March 2014 (a seven-year period) the loop was made without an outburst. The next close approach to our Sun, perihelion, will take place on February 19, 2021. Will we be treated to another show?
— James Guilford
Stephens Memorial Observatory 