This comet is due to pass closest to our sun and Earth in December 2018. It’s already the brightest comet in the night sky, visible to astronomers with telescopes and binoculars. A new image shows the comet’s rotation!
Using specialized filters to observe cyanogen gases produced by comet 46P/Wirtanen, astronomers were able to capture new images of the celestial visitor, showing gas spirals as the comet rotates. Astronomer Tony Farnham and colleagues reported these results via the Central Bureau for Astronomical Telegrams on November 10, 2018, and the image was also posted on University of Maryland’s current status page for Wirtanen on November 26.
These new observations suggest comet 46P/Wirtanen has a rotation period of 8.91 hours.
Will this comet become visible to the eye in December, as hoped? No one knows yet, and comets are known for being unpredictable. As of late November, observers around the world are reporting that Comet 46P/Wirtanen is showing a brightness or visual magnitude between 5.5 to 6.5. That is on the cusp of visibility to the eye, in theory.
However, the dim light reflected from comet Wirtanen is spread over a large cometary atmosphere.
This may mean that – as December arrives, the month in which the comet should look brightest from Earth – Wirtanen may look more diffuse and harder to see than expected. Like most comets, it will surely require truly dark skies to be seen. As the comet may not be easily visible for casual observers, a good option would be to verify if your local astronomy club will be hosting events for observing comet 46P/Wirtanen.
As is always best with comets, keep your expectations low. Still, comet 46P/Wirtanen might still provide nice views through binoculars and small telescopes, especially away from city lights.
Want charts showing the comet’s location, plus pics of the comet? Read more: Comet 46P/Wirtanen is 2018’s brightest comet
Bottom line: Comet 46P/Wirtanen can be seen rotating in this new image from Tony Farnham and team, posted at University of Maryland.