You can expect a ghostly green blob to grow brighter in the sky near Orion in the coming days, as Comet 46P/Wirtanen makes it closest approach to the Earth in 20 years this weekend. If you're anxious about risky comets striking Earth, however, breathe easy: Wirtanen is not on the list of those that astronomers worry about.
"This comet has already been visible in larger amateur telescopes, and while the brightness of comets is notoriously hard to predict, there is the possibility that during its close approach comet 46P/Wirtanen could be visible with binoculars or to the naked eye".
Its closest passage by the Earth will be on Sunday, when it will be 7.2 million miles from the planet.
SUPPLIEDDirections to spot the 46P Wirtanen comet passing Earth
What it does mean is you will be able to catch a glimpse with the naked eye, especially on December 16th, so long as light pollution doesn't block out the view.
The proximity of 46P/Wirtanen provides an opportunity to research the tail of the comet and see farther into the nucleus.
For nonscientists, this lasting memorial to a Wisconsin comet hunter will simply be a fresh opportunity to look up - if the winter skies cooperate.
"This will be the closest comet Wirtanen has come to Earth for centuries and the closest it will come to Earth for centuries".
He added: "We have not had a comet this well placed and bright for many years". It should be just as visible for a week or two because its appearance will change gradually.
Astronomer Carl Wirtanen discovered the comet in 1948 at Lick Observatory on Mt. Hamilton in Santa Clara County, California.
The comet reaches its closest point to the sun on Dec. 13 and will be at its brightest on Dec. 16, the evening before it makes its closest approach to Earth Dec. 16.
"Look towards the east with a small pair of binoculars or a telescope to see the green, fuzzy comet". Looking at the radio-range wavelengths of light the comet releases, astronomers can examine the distinctive gases that come off of the visitor. It has a diameter of about three-quarters of a mile - a relatively small comet. "This is because the comet will be unusually large in angular size, as well as appearing very diffuse ... nearly ghostly". It orbits the sun once every 5.4 years, passing by Earth approximately every 11 years, but its distance varies and it is rarely this close. The comet appears to be a close twin to comet Hartley 2, the second target of the Deep Impact mission. "The comet will even pass through the observing field of the Transiting Exoplanet Survey Satellite (TESS)". But the atmosphere around the comet, or coma, is bigger than Jupiter. Find the darkest skies you can, and settle in for a show; you may see around 1 meteor per minute, including both fainter streaks and bright fireballs.