From Halley to Hale-Bopp to Shoemaker-Levy 9, their names have a certain pop star quality to them. For a while, they're all the rage, then they're all but forgotten, at least by the general public.
Comets come, and comets go and then sometimes they come again.
Halley's Comet is possibly the most famous one that comes around on a fairly regular basis, at least from a geological standpoint. That's how it came to be called Halley's Comet. The Astronomical Society of the Pacific gives the following account on the organization's website: "The British astronomer Edmond Halley (1656-1742) was using Isaac Newton's ideas of gravitation to analyze the motion of bodies in the solar system. He noticed that the records for the bright comets of 1531, 1607, and 1682 showed that all three comets had very similar orbits. He drew the bold conclusion that all three were really the same comet, trapped by the gravitational pull of the outer planets, and predicted that the comet would return in 1758-59. The comet was found again on Christmas night 1758 and was then named in the late astronomer's honor."
It has since returned every 75 years, like clockwork.
Famously Mark Twain linked his life span with a single orbit of Halley's comet around the sun: "I came in with Halley's Comet in 1835. It is coming again next year [1910], and I expect to go out with it. It will be the greatest disappointment of my life if I don't go out with Halley's Comet. The Almighty has said, no doubt: 'Now here are these two unaccountable freaks; they came in together, they must go out together.'"
Twain, or more properly Samuel Clemens, predicted accurately, passing on April 21, 1910.
Visible over Harford County this month is another such wonder of the ages, a comet known officially as c/20145 Q2 but more memorably by the last name of the human being who first noticed it Australian Terry Lovejoy.
There are plenty of things to look at in the night sky over Harford County. Even with its urbanization, it is still possible to pick out many major constellations. From time to time, Mars puts on quite a show, thanks to the way the sunlight reflects off its thin atmosphere.
And then from time to time there are comets, which appear as streaks in the sky, moving incrementally night after night over a span of a few days or weeks. Lovejoy is unusual among them insofar as it will be visible to casual observers equipped only with binoculars, according to Bob Kesler, president of the Harford Astronomical Society President.
It's a natural wonder well worth venturing outside to get a look at. Sure, the weather promises to be cold, but in these parts cold winter nights are the clearest for seeing details in the night sky.
There may be plenty of other diversions demanding our attention, but each comet, as Twain pointed out, can be seen only for a brief span in a human lifetime. It would be unfortunate to miss getting a look at one, especially at a time of year when the looking promises to be pretty good.