Just a few short days after the Geminid meteor shower peaks on December 13, star gazers will be treated to a special appearance by Comet 46P/Wirtanen — hailed as the brightest comet to light up the sky in 2018, according to Comet Watch. First spotted 70 years ago from the Lick Observatory in California, Comet 46P passes by our planet once every 5.4 years. But this year’s flyby promises to be particularly memorable. Here’s why.
Four Reasons Not To Miss Comet 46P
1. Very close approach
The icy space rock will be making a very close approach to our planet in 2018, coming within 7.1 million miles (11.5 million kilometers) of Earth — or about 30 times the distance between Earth and the moon, notes EarthSky. Judging by comet standards, this is a particularly close encounter. By comparison, Comet 21P/Giacobini-Zinner — which is about to make an important entrance on September 10, as the Inquisitr recently reported — will be passing at five times the distance, approaching at 36.4 million miles (58.6 million kilometers) of Earth.
Meanwhile, the “Incredible Hulk” green comet that streaked across the sky on August 7, as reported by the Inquisitr, only came 70 million miles (113.4 million kilometers) from our planet — 10 times farther away than Comet 46P will be in December.
In fact, this is the comet’s closest approach in a long while. The last time Comet 46P came close to Earth was in 2013, but that visit only brought it 564 million miles (907 million kilometers) from our planet. This year’s close approach will occur on December 16, four days after the comet reaches perihelion, or the closest orbital point to the sun. The video below, uploaded on YouTube by Comet Watch, details the comet’s trajectory as it enters our solar system.
2. Brightest comet of the year
Another interesting thing about Comet 46P is that it is what astronomers call a hyperactive comet. Although relatively small, measuring just 0.7 miles (1.2 kilometers) in diameter, this comet will be unexpectedly bright when it swings by in December.
This is because “46P/Wirtanen belongs to a small family of comets that boast a higher level of activity than expected for their nucleus size,” explains Comet Watch. These comets “emit more water vapor than they should,” which makes them shine a lot brighter than other comets of the same size. This year, Comet 46P is expected to reach a visual magnitude of 3 — the highest in its entire history.
“This is the brightest prediction of known and future passes of this comet. This is also currently the brightest prediction for all comet passes in 2018,” states Comet Watch.
In any given year, Comet 46P is usually spotted only with the help of telescopes or binoculars. This year, however, star gazers should be able to catch a glimpse of the comet with the unaided eye.
Thanks to its brightness and close proximity to our planet, there’s a good chance that Comet 46P will be visible to the naked eye on the day of its closest approach to Earth. As FiOS 1 News meteorologist Joe Rao points out, Comet 46P will become “about as bright as the faintest star in the Big Dipper,” an asterism in the Ursa Major constellation (the “Big Bear”).
“So, if you know where to look in the sky, it will be against the winter constellations of Taurus (‘The Bull’), near the Pleiades and Hyades star clusters,” says Rao.
4. Great Observation Conditions
Aside from being a very close comet encounter of possible naked-eye brightness, December’s event is also expected to offer excellent viewing conditions everywhere on the globe.
According to astronomers at the University of Maryland, Comet 46P will be visible to sky watchers both in the Northern and the Southern Hemisphere and will shine in the sky almost the entire night.
The comet will remain visible for many hours long after December 16, although its glow is bound to fade the farther away it gets from Earth. By February 3, 2019, its brightness will decrease to a magnitude of 8, according to the Comet Watch video.