- nemesis maturity Published on Aug 31, 2018
Sky watchers are in for a rare treat over the coming months as comet 46/P Wirtanen is set to be visible with the naked eye in the night sky. On 16 December 2018 the comet will fly by Earth, making this pass the brightest one predicted, and the brightest close approach for the next 20 years. It is also the10th closest comet in modern times. The comet will be well placed for Northern and Southern Hemisphere observers near the end of 2018. It will appear in the constellation Taurus during its closest approach to Earth. 46P/Wirtanen is a short-period comet with a current orbital period of 5.4 years, and it was discovered on January 17, 1948, by the American astronomer Carl A. Wirtanen.
The space rock belongs to the Jupiter family of comets, all of which have aphelia between 5 and 6 AU. Its diameter is estimated at 1.2 kilometres (0.75 mi). The 2018 close approach, combined with Wirtanen’s brightness provides an opportunity to study a potential future spacecraft mission target in detail. 46/P will be so close that amateur astronomers can help study it, too. A worldwide observing campaign has been organized to capitalize on the favorable circumstances of this apparition. Astronomer Tony Farnham of the University of Maryland says, “46P has a small nucleus, but is known to be a ‘hyperactive’ comet. It is probably ejecting ice crystals from its surface, producing higher than normal activity.” This hyperactivity may contribute to the naked-eye brightness of 46P. It also makes the comet somewhat unpredictable with unexpected surges in activity—and visibility—possible as it passes by. Comets are some of the most interesting objects in the solar system. Water that filled the ancient oceans of Earth might have been delivered by comets. And there is growing evidence that many comets (as well as some primitive asteroids) contain molecules key to life.