Periodic comet 46P Wirtanen is rapidly rising into our midnight skies, and rising toward naked-eye visibility.
Here is the eastern scene an hour after midnight on Friday. As the night goes on, the comet climbs higher.
An arrow through its head shows its path from 5 days before this time till 5 days after; the dots are at intervals on one day.
Over westward along the ecliiptic, Mars’s slower path is drawn in the same way.
Comets’ tails are driven outward from the Sun, so the tail – which may not really be so long – points toward the place in the sky what we mark as the “anti-Sun”.
46P means that the comet is the 46th one with a oeriodic orbit firmly enough known that it could be given a number. It was the first comet discovered in 1948, as it was coming away from a perihelion in December 1947. It had a period of about 6.7 years, which has been gradually shortening, and this is its 11th observed apparition.
It is now rushing north toward a perihelion on December 12, on the border of Aries and Taurus, just outside our orbit, and favorably placed, in the evening sky 148° from the Sun. The Moon is out of the sky, being New on Dec. 7. On Dec. 16, as 46P ascends through the ecliptic plane, it will be nearest to us (about 0.79 astronomical units or Sun-Earth distances, 118 million kilometers) and brightest.
These figures are based on orbital elements from the Minor Planet Center’s website, but recent observations may have refined them. Indeed the comet is proving remarkably bright and with a large cloudy coma, and may reach a magnitude of about 4. This is well into the naked-eye range, though for cloudy objects magnitude estimates are tricky, because the light is spread, unlike that of a star.
By the end of the year this comet (discovered by a Finn, or at least an American with a Finnish name) will be as far north as 57.5°, in the constellation Lynx.
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DIAGRAMS in these post are made with precision but have to be inserted in another format. You may be able to enlarge them on your monitor. One way: right-click, and from the drop-down list choose “View image” Or from that list choose “Copy image”, then put it on your desktop, then open it. I would welcome learning of any other methods.
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Cato ended every speech to the Roman Senate with: “Carthage must be destroyed.” I want to end every message with: “If you’re not doing something to slow carbon emission, you’re speeding the end of civilization.”
From Wikipedia:
Carl Alvar Wirtanen (November 11, 1910, Kenosha, Wisconsin – March 7, 1990 Santa Cruz, California) was an American astronomer and discoverer of comets and minor planets who worked at Lick Observatory.[2][3] He was of Finnish ancestry.
Guy, this Comet reminds me of Comet IRAS-Araki-Alcock (C/1983 H1) although it is coming closer, I believe than Hyakutake?
I haven’t seen Wirtanen yet, but we’re in for one night of mostly clear weather tonight, so I’ll try to see the comet, although I fear that my urban light pollution will be brighter than the comet’s surface brightness. I should have better chances seeing Mars and Neptune, and Juno.
“Carthago delenda est” might become “carbon must not be burned,” or “net carbon emissions must be zero.”
Yes, I think of adding “Carbo delenda est” – “We must get rid of carbon”. Unfortunately the Latin word (which meant burnt wood or charcoal) is masculine, so I ought to say “Carbo delendus est”. But I think of enshuddering Latin scholars and saying “Carbo delenda est” anyway. The phrase has become a tradition. As with many quotations, it’s been improved by erosion. Cato’s usual words were “Ceterum autem censeo Carthaginem esse delendam – Furthermore also I consider Carthage to be worthy-of-being-wiped-out”. Marcus Porcius Cato was known as Cato the Elder or Cato the Censor; “censor” was an office that many Roman politicians held in the course of their careers; they regulated some things including public morality; I assumed that Cato in particular was nicknamed “the Censor” because he was a stiff old conservative, hostile to all things new-fangled or lardy-da, such as Greek culture. But maybe it was also because of his tiresome ending of speeches on whatever subject with those words, “Censeo…” – “I deem…”
I added a short paragraph about the tail of the comet pointing at the anti-Sun.
Just so long as we don’t destroy the carbon by burning it, as Scipio and his legions destroyed Carthage.
By the way, I walked up to the top of Bernal Hill around 10 pm PST last night, when Comet Wirtanen was culminating. If I didn’t have a good chart I never would have seen the comet. But knowing exactly where to look, the comet was visible through 10×42 image-stabilized binoculars, a faint and nondescript brightening that faded into the background sky without any clear edge. I also saw Mars and Neptune, Uranus, and Juno, along with good views of everybody from Cygnus to Orion. It’s good to look up.