Even every-day binoculars can make comet observing more enjoyable, though bigger and high-magnification models have the advantage with fainter targets. The 15×70 binos (left) and 10×50 model are fine choices for many comets. Photo by Gary Seronik
By Gary Seronik
Comet Lovejoy is currently putting on a fine, if unspectacular, display in the evening sky. And like many comets, it’s well seen in binoculars. But are some binos better for the job than others? Yes, but much depends on the comet.
These icy visitors from the remote edge of our solar system generally fall into four categories. Most numerous are the garden variety “barely there” comets. At any given time, there are dozens of them slowly drifting across the sky. Then there are comets that almost achieve naked-eye brightness. We get one or two of these pretty much every year. Next, we have comets like Lovejoy that are bright enough to be seen without optical aid. These turn up every couple of years. Finally, there are spectacular, gosh-wow! showpieces such as Hale-Bopp and Hyakutake. We’re lucky to see one of those in a decade.
For the most impressive comets, I prefer binoculars that have a wide field so that I can take in as much of the tail as possible. Low-power models (such as 7×35s or 7×50s) generally fit the bill. Even for great comets, such as Hyakutake, which for a time sported a tail spanning many tens of degrees, binos help draw out structure and detail invisible to the naked eye. When it comes to comets like the current Lovejoy, I find my 15×45 image-stabilized binos get the most use, followed closely by my 10×50s. For these often tail-less examples, magnification is usually a higher priority than an expansive field of view. The same holds true for comets just shy of naked-eye brightness. A little extra aperture is a big help too, which is why I’ll often grab my 15×70s when dealing with comets in this category. If I have to consult charts frequently (which I generally do with fainter comets), I make sure I put the binoculars on a tripod so that I don’t have to re-aim them every time I look away.
Finally, for the run-of-the-mill fainties, I normally just use a telescope, although some people prefer giant binoculars. Indeed, Yuji Hyukutake discovered his most famous comet when it was a faint nothing by sweeping the sky with a pair of 6-inch binos. I guess if I had binoculars that big, I’d probably use them too!