Conditions are good to see ‘Christmas comet’ near St. Louis tonight
Comet 46P/Wirtanen began brightening in November. It made its closest approach to Earth on Sunday and is visible with the naked eye. The comet is coming within 7 million miles of Earth — a proximity that won’t happen again for 20 years. That’s 30 times the moon’s distance from us.
The comet was the brightest on December 16, as bright as the star in the constellation of the Little Dipper’s handle, according to NASA. You’ll still be able to see it tonight. But, it won’t be as bright as Sunday night. It’s currently the brightest comet in the night sky, and the brightest of 2018.
FOX 2 Meteorologist Chris Higgins says there should be good comet-watching weather tonight (December 17, 2018.) Although it could be a bit chilly with temperatures dipping quickly back into the 30’s and 20’s overnight.
The best viewing will be around 10:30 PM tonight, looking south, then almost straight up (about 79°) from there. Reports from some viewers from Sunday night indicated it was tough to find, and appeared to be not much more than a fuzzy white ball, without the classic tail so often depicted in cartoons and artistic renderings.
It may be worth having a look if you are outside tonight and away from the city lights, preferably south of St. Louis. This is a great website for tracking the comet location as it rises and sets in the sky tonight.
Weatherwise, we will be cloud-free. But, the moon will add some light to the night sky until it sets around 2:30am.
The University of Maryland’s astronomy department said that Comet 46P will be the 10th closest comet since 1950 because few comets are ever bright enough to be seen with the naked eye.
The “Christmas comet” appears in our sky once every five years as it orbits the sun. It was closest to the sun on December 12. The comet is named for the man that first observed it in 1948, Carl Wirtanen, a senior observing assistant at California’s Lick Observatory.
“Look towards the east with a small pair of binoculars or a telescope to see the green, fuzzy comet. It will be near the constellation Orion, or the saucepan,” said Brad Tucker from the Australian National University Research School of Astronomy and Astrophysics.
Much like watching a meteor shower, you’ll want to be in an area without much light pollution. Look up anytime between twilight and sunrise to catch a glimpse. Check TimeandDate.com to figure out the best time in your part of the world.
If you aren’t able to view it, the Virtual Telescope Project will stream observations from its robotic telescopes.
So why does the comet look fuzzy or ghostly? It’s three-quarters of a mile across with a core that’s less than a mile wide. But the atmosphere around the comet, or coma, is bigger than Jupiter. When it passes the sun, this icy comet essentially experiences some melting. That’s what creates the glowing green cloud.
The diffuse nature of the coma and its glow may actually make it more difficult to view, especially if using binoculars or a telescope. Astronomers have predicted the comet will have a magnitude of 4.2, which means that a dark, clear sky and an absence of ambient light will most likely be needed to see it.
And unlike other comet sightings, this comet’s tail will be behind it when it passes, meaning we most likely won’t see it unless the tail develops a curve before its closest approach to Earth.
Comet 46P was originally chosen by the European Space Agency to land the Rosetta probe on its surface, but launch delays caused a new target to be selected. (Rosetta went on to land on Comet 67P in 2014.)
“Wirtanen’s comet could easily be chosen again for another mission,” said Jim Lattis, director of the University of Wisconsin astronomy outreach center, UW Space Place. “So that means watching this comet each time it comes near could be important.”
Much like the OSIRIS-REx mission to study the asteroid Bennu, a remnant from the early solar system, Comet 46P could provide similar insight.
“We’re getting a look at stuff that was formed during the formation of the solar system and has been out in the deep freeze since then,” Lattis said. “When these things come in and we get a chance to study them, we’re seeing some of the raw materials out of which the Earth and the other planets and everything else formed.”