The big buzz in skywatching circles these nights is Comet Holmes (officially known as 17P/Holmes). Sky & Telescope online has a story that calls this late-bloomer comet “the weirdest new object to appear in the sky in memory.” I think that’s a bit overstated; what do they mean by “weird”?  Weird would be something like sporting eyeballs or something, not the fact that it’s brightening up. Comets brighten up during parts of their orbits. However, this one is brightening up after it has rounded the Sun, but I don’t think that makes it weird. I think it makes it interesting.

However, I digress.There’s more history here, including some nice images showing recent behavior of this oddball comet, if you want to follow some of the thought about this unusual periodic cometary visitor.<br /><p>Holmes is sporting some tail activity, although since we’re looking along the long axis of its tail, we don’t see it as well as if the tail was streaming across our field of view. (That would require a different viewing geometry.)

So, what’s causing this thing to brighten up?  Lots of speculation out there, mostly around the idea that this thing is losing dust in great quantities for some reason. It may have suffered an impact with solar system debris, causing a huge chunk of the surface to flare away and release massive amounts of dust. Remember that comet nuclei are chunks of ice and dust, so whenever the hard surface blows away (for whatever reason) a release of dust will cause the comet to appear to brighten (because the increased amount of dust is reflecting sunlight, for one thing).

While folks who study such things discuss what’s causing Holmes to brighten, check it out from your own backyard (or other safe place for observing). Just head out sometime an hour or so after dinner in the evening and look for the constellation Perseus. Need a starchart? Go here.