MESSENGER image of comet 2P/Encke during its closest approach to Mercury. At that time, Encke was approximately 2.3 million miles (3.7 million kms) from MESSENGER and 32.7 million miles (52.6 million kms) from the Sun. The image is 7° by 4.7° in size and has been slightly smoothed to enhance the faint tail of the comet. The tail was oriented nearly side on to MESSENGER in this image and is seen to stretch several degrees from the comet’s bright coma in the direction away from the Sun.
NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Southwest Research Institute