Get ready for an 'out of this world' sighting this December.

According to Astronomy Ireland, a 'Christmas comet' is due to pass unusually close to Earth, right in time for the festive celebrations.

Comet Wirtanen, a cosmic snowball of frozen gases, rock, and dust that orbits the Sun, is set to fly closer to Earth than it ever will during our lifetime.

Experts state that the comet will be seen in Irish skies around mid-December; so close that it may even be visible to the naked eye from city suburbs. Although, best to have your digital cameras or binoculars on hand to get as good a view as possible.

Comet 46P/Wirtanen was looking incredible last night from the Bighorn Mountains of Wyoming. It’s already naked eye visible and will get even brighter next week at closest approach. @StormHour @Photo_Space @universetoday @EpicCosmos @earthskyscience

— Kevin Palmer (@krp234) December 7, 2018

The blueish-hued 'hyperactive comet' has a diameter of about 1.2 kilometres and passes by Earth every five years or so. 

The Mirror reports that Comet 46P/Wirtanen will make its approach on December 16th, but will also be visible in the days leading up to then. The paper states that it will be brightest in the sky on December 12th.

The Sun writes that, "sky gazers can catch a glimpse of 46P/Wirtanen on Wednesday evening by heading to a dark spot and looking south, as the comet is so bright it will be visible to the naked eye."

Comet 46P/Wirtanen and its ion tail captured by Gerald Rhemann on December 3, 2018 from Farm Tivoli, Namibia

— Massimo (@Rainmaker1973) December 5, 2018

"It is the brightest comet of 2018 and marks the 10th closest comet pass in 70 years, skimming to within 7.1 million miles of our planet, or 30 times the distance to the moon," the paper adds.

For more information about how to see the comet, watch the video below.

NASA writes that Comet 46P/Wirtanen is a member of the Jupiter family of comets. 

"It will be at its closest distance to Earth in over four centuries," the space body confirmed.

Have you ever seen a comet before? Let us know in the comments below.

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