Wirtanen (46P) will be approaching the sun. And it may be bright enough that we’ll be able to see it without a telescope or binoculars. So make sure you’ve got lots of layers on, grab a thermos of hot cocoa, and head out to watch the sky.
Comets are dirty snowballs. Only much, much bigger! They are left over from when the stars and planet were formed billions of years ago. Comets begin their existence as huge chunks of rock and ice floating around in the Oort Cloud. That’s a cloud of icy bodies located about 186 billion miles from the sun, way past Pluto and its Kuiper Belt buddies.
The thing about comets is - you don’t see them until they’re close. When a comet comes near the Sun, the heat warms it up and causes the ice to sublimate. That’s a nifty word that describes what happens when ice turns into steam without becoming water first. Ice boiling off as steam releases dust and gas, too. All of this creates a thin atmosphere around the snowball nucleus as well as a tail. The tail can stretch millions of miles! Then the comet goes around the Sun and heads back into space. After a while we lose sight of it.
The last time 46P/Wirtanen flew by was in April of 2013. This year the comet will approach the sun on December 12 and fly closest to the Earth a few days later, on December 16. According to astronomers, this fly-by will be close, by comet standards - around 7.1 million miles away. That’s about 30 times as far as the moon’s distance from Earth.
Find out more! Check out this video and read more here.