On December 4, Comet Wirtanen (inset) was in the constellation of Eridanus, the River, and was just at the limit of visibility to the unaided eye. It is making a beeline for the stars of Taurus, the Bull, and will pass between the Pleiades and Hyades star clusters in mid-December. The “X” marks the approximate location of the comet on the night of December 16, when it will become the 10th closest comet to brush by the Earth since 1950. After the Moon sets that night, the comet could be visible to the unaided eye as a ghost-like fuzz ball. Binoculars will enhance the view.Comet Wirtanen, also called comet 46/P, is due to make a very close pass by the Earth in December and might — emphasis on might — become visible to the naked eye around midmonth.
Comet Wirtanen was discovered in 1948 by Carl Wirtanen at California’s famous Lick Observatory. It follows a 5.4-year orbit around the sun, going from just inside of Jupiter’s orbit to just outside of Earth’s orbit. Over time, close encounters with both planets keep the comet’s orbit all stirred up and it never quite follows the same path around the sun twice.
On this pass, Comet Wirtanen will reach perihelion — its closest point to the sun — on Dec. 12, just four days before its closest approach to Earth. On Dec. 16, the comet will pass only 0.077 astronomical units from Earth. That’s equivalent to 7.2 million miles, or about 30 times the distance from the Earth to the moon. This puts Comet Wirtanen in the record books as the 10th closest comet to brush Earth since the year 1950, and the 20th closest in recorded history.
At 1 mile in diameter, Comet Wirtanen is relatively small, as comets go, but it is classified as a hyperactive comet. That means that it can become brighter than most comets its size. Because comets are basically dirty snowballs, they are most violently boiling away and brightest when they are closest to the sun. Comet Wirtanen’s timing of closest approach to the sun and closest approach to Earth is ideal for creating the best show possible.
Getting a good view of Comet Wirtanen will require finding a dark observing location away from city lights. It also will require dodging the waxing moon, which becomes full Dec. 22 and will temporarily bring comet-watching to a grinding halt.
On Dec. 15, the …read more
Via:: Steamboat Today