Comet 46P/Wirtanen is three-quarters of a mile wide and can already be viewed with a telescope. Astronomers have reported seeing its green aura glow as far as Jupiter, but NASA says the best view is yet to come.
The comet has a short orbit time of 5.4 years, and will reach the Sun on 12th December. Comet 46P/Wirtanen will then pass by Earth at its closest distance on 16th December, just above our eastern horizon, lighting up the night sky.
Last month, the US Space Agency shared this picture of Comet 46P/Wirtanen on its approach through the Solar System as its Astronomy Picture of the Day.
“Periodic Comet 46P/Wirtanen is now the brightest comet in the night sky, but too faint to be seen by eye,” they explained.
“Fluorescing in sunlight, its spherical coma is about half the angular size of a full moon in this southern hemisphere telescopic view from November 7. Then the comet was about 2 light-minutes away or 35 million kilometers from Earth-bound telescopes, so the pretty greenish coma seen here is around 150,000 kilometers across.”What’s up in the sky to see in December? You can expect to see up to 120 meteors per hour during the Geminid meteor shower, catch your last view of Saturn for several months and spot a visible comet. Find out when and where to look up: https://t.co/DCXtAezKQt pic.twitter.com/cSSnDTHxip— NASA (@NASA) December 2, 2018
NASA’s Jet Propulsion Laboratory then explained on Twitter that Comet 46P/Wirtanen “will be only 7.2 million miles or 11.7 million kilometers from Earth and will reach an estimated naked-eye magnitude of 3 to 7.5” as it passes on 16th December.
Astronomers say the comet is a regular visitor to our Solar System, and was previously “the favoured rendezvous target” for the Space Agency’s Rosetta Mission.
If you can’t see Comet 46P/Wirtanen from space on 16th, track its progress online via the Virtual Telescope Project.