Brightest comet of the yearcan be seen as it zips past Earth
If you have clear skies and are willing to bravethe chilly temperatures, you might want to head to a dark site and look for apassing visitor.0
46P/Wirtanenis beginning to brighten in the sky
Nicole Mortillaro · CBC News · Posted: Dec 08, 20184:00 AM ET | Last Updated: 9 hours ago
Comet 46P/Wirtanen, seen here on the night of Dec.4 via telescope. (Fritz Helmut Hemmerich)
If you haveclear skies and are willing to brave the chilly temperatures, you might want tohead to a dark site and look for a passing visitor.
Comet46P/Wirtanen, first discovered in 1948, will have its closest encounter withEarth on Dec.16. But it’s already visible in the sky.
While this isthe brightest comet of the year and the 10th closestcomet in modern times](http://wirtanen.astro.umd.edu/close_approaches.shtml), don’t expect one with a well-definedtail, a hallmark of comets.
At the moment,Wirtanen — a small comet at just 1.2 kilometres in diameter — is a fuzzy,bluish object in the southern sky. Recent photos do show a thin tail, butnothing very pronounced.
Wirtanen will likely brighten as it makes itsclosest approach to the sun on Dec. 12.
Malcolm Park captured this image of comet46P/Wirtanen from Prince Edward County, Ont., on the night of Dec. 5. (MalcolmPark)
Comets, oftenreferred to as “dirty snowballs,” are leftover collections of dust,gas and ice from the formation of our solar system. Most are from two regions —
the Kuiper Belt and the Oort Cloud — at theouter edge of our solar system. Once in a while they get knocked out of theseregions and begin a voyage around the sun.
As acomet approaches the sun, its ice sublimates (changes directly from asolid to a gas, skipping the liquid phase), which produces its characteristictail. A comet’s brightness depends on its size and how much ice andgas it contains.
Where to look
The brightnessof celestial objects is on a scale that goes from the very brightest — the sun— to the dimmest. And it doesn’t go in the direction you’d think: the lower thenumber (negative values) the brighter the object.