October 26th, 2007 by webmaster
Comet 17p/Holmes was an unassuming, minor short period comet until a few days ago. At magnitude 17 it was invisible even in large amateur scopes. This comet has an orbit that brings it no closer to the sun than Mars, and no farther than Jupiter. Although discovered in 1891, it was lost in 1906, and not re-aquired until 1964. When first observed, the discoverer (Holmes, of course) noted a significant brightening over a brief time span, which was largely discounted until observed independently.
Well, 17p/Holmes has repeated this little trick. And how.
Over the span of a few hours, this little invisible dot brightened to naked eye visibility! Now, when a comet is described as “naked eye visibility”, the term often refers to ”visible to a dark adapted eye in a dark sky location” - but this comet soard to magnitude 2, and is easily visible to the naked eye in a light-polluted city during a full moon! The comet, currently in Perseus, is conveniently placed in the eastern evening sky. It’s distance means that it is point-like to the unaided eye, but shows its true form - and colours - with binoculars or a small scope.
This thing is really unique. Perhaps because of it’s position nearly opposite the sun as seen from Earth, we may be watching a tail form, from the head end of the comet. Even in binoculars, Holmes displays a bright core, slightly offset from the centre of a fuzzy disk or coma. While most comets I have seen display some colour, often green or blue-hued, Holmes is distinctly yellow. The result is an eary resemblance to an eyeball.
At this distance, and several months after perihelion, there is still a mystery surrounding the sudden outburst. In all, a very exciting object. I look froward to watching its progress over the coming months, or as long as it remains visible!
digital “sketch” of 17p/Holmes
Posted in Astronomy |