Forked tongues allow snakes to smell in stereo – each fork senses slightly different chemicals in the snake’s vicinity and feeds a separate signal to its brain. When combined, they create a complete “picture” of the reptile’s odiferous world. In much the same way, the two ears on opposite sides of our heard allow us to hear the world in rich stereo sound.
Lovejoy’s forked tail is hardly an operative organ, but it’s sure amazing sight for stereo eyes. Composed principally of carbon monoxide gas, each of the two primary rays is incredibly well-defined. Gases like water vapor, carbon monoxide and carbon dioxide boil off the nucleus as the Sun warms the comet and help create its big blue-green head or coma. As described here before, the solar wind ionizes or electrifies the gases which allows the magnetic fields embedded in the wind to peel back the gases to form a the glowing gas or ion tail.
I hope you’ve had the chance to see Comet Lovejoy. While the naked eye view isn’t impressive (though always a pleasure to behold any comet without optical aid), binoculars clearly show the faint, smoky tail extending east of the fuzzy head. In a telescope, even a fairly large one like the 15-inch (37-cm) reflector I use, the fainter rays are indistinct, though the forked tongue shows a little more clearly.
With the moon now returning to the evening sky (see below) and the comet starting to fade, it will gradually become more difficult to see with the naked eye. By mid-February, Lovejoy will probably have dimmed to the naked eye limit of around magnitude +6. But if you use binoculars, you’ll be able to follow our feathery friend through full moon and beyond.
Northern skywatchers are fortunate that the comet continues to move north and ever higher in the sky. By late February it will be circumpolar from many locations and remain visible all night.
You can use the map to help you find Lovejoy as it climbs into Triangulum the Triangle this weekend and from there to Andromeda and Cassiopeia.