Earlier this summer perhaps you were among the many who managed to get a peek at Comet NEOWISE, a once-in-a-decade bright visitor to our cosmic neighborhood.
I’d better clarify that first sentence. No, Comet NEOWISE won’t be returning to put on another spectacle in about 10 years. It will be more like six and a half millennia before it drops by again. But NEOWISE was a relatively rare event for stargazers, a naked-eye comet that many people could see for themselves. Such bright comets tend to crop up only once every 10 years or so.
You may recognize some of the names: Ikeya-Seki, (1965), Kohoutek (1973), Halley (1986), Hale-Bopp (1997), and McNaught (2007) for example.
Comets are fickle celestial objects. Predictions about their eventual brightness as they near the sun and the earth are notoriously unreliable. Depending on their paths and behaviour near the sun, some may only be visible in one hemisphere.
Those that do become naked-eye visible, and especially those that become visible in city night skies, are exceedingly rare. NEOWISE, for Near-Earth Object Wide-Field Infrared Survey Explorer, the space telescope that first noticed it this year, fit both bills. Even while standing under a city street light I was able to make out this comet and photograph it.
Comet NEOWISE became a teachable moment for me. I was able to promote interest in astronomy to families in my neighborhood through Facebook posts. Initially, no one paid much attention, but after I posted photos taken in a very small neighbourhood park, not even a hundred metres from my home, I was surprised the following night to see up to 50 people around midnight, all there to see the comet.
It was difficult to get an exact count as this little park, perhaps through municipal oversight, has not a single light, and, even more helpfully, sits on a small crest. I have now dubbed it as my personal dark park, and this despite it being surrounded by homes and street lights that for the most part sit lower than the park itself.
Being mindful of COVID-19 concerns with shared eyepieces on a telescope, I only set up a camera with a screen so that others interested in the comet could compare what they saw with their eyes to what a camera could bring out with a longer exposure.
It was wonderful to encounter families with youngsters eager to see the comet. For some, it may well be the only comet they will ever see. I certainly remember my father taking me out in childhood early one morning and driving above the fog to the top of a nearby peak to see Ikeya-Seki.
Comet viewing this time highlighted for me the difference in visual acuity between adults and children. On several occasions I noticed that it was the youngsters who spotted the comet ahead of their parents.
Here in the Vancouver area Comet NEOWISE was not a standout celestial object unless you were in a truly dark area. Initially it was better seen in early morning skies. Certainly there was some confusion about when it would be brightest. There was the matter of closest approach to the sun, and closest distance to earth. As it was, from my observations, the comet was easiest to spot somewhere in between these two points.
I managed to photograph NEOWISE on several occasions, in the small dark park, and also under a street light in front of my house. Time exposures of around 10 seconds produced the best results, bringing out a little more detail than could be seen by eye.
Some were able to photograph NEOWISE with a cellphone, but due to the need for a time exposure it would have to be fixed to a tripod or other restraint.
NEOWISE is no longer a naked-eye object. I for one am eagerly awaiting the next celestial visitor to our skies. Hopefully it won’t be a decade-long wait.
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