https://phys.org/news/2018-12-nasa-telescopes-brightest-comet.html

The inner part of a comet's coma is normally not accessible from Earth. The close fly-by of comet 46P/Wirtanen allowed astronomers to study it in detail. They combined the unique capabilities of Hubble, NASA's Chandra X-ray Observatory, and the Neil Gehrels Swift Observatory to study how gases are released from the nucleus, what the comet's ices are composed of, and how gas in the coma is chemically altered by sunlight and solar radiation.

NASA's Stratospheric Observatory for Infrared Astronomy, SOFIA, took this image of the comet on Dec. 16 and 17 when the aircraft was flying at 40,000 feet.