NASA MESSENGER Image: Comet C/2012 S1 aka ISON

NASA's MESSENGER spacecraft took this image of comet C/2012 S1 (ISON) during its closest approach of Mercury at 01:54:30 UTC on November 20. 

ISON was approximately 22.5 million miles (36.2 million kilometers) from MESSENGER and 42.1 million miles (67.8 million kilometers) from the sun. 

The image is 7° by 4.7° in size and has been slightly magnified and smoothed to enhance the faint tail of the comet. 

The tail was oriented at an angle to MESSENGER at the time and is foreshortened in this image; however, some faint structure can still be seen.

This image was acquired by the Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS) aboard NASA's MESSENGER spacecraft. 

The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet.

Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Southwest Research Institute