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As comets C/2012 S1 ISON and the well-known short-period comet 2P/Encke both approached their closest distances to the Sun in November, 2013, they also passed close to the MESSENGER spacecraft orbiting the innermost planet Mercury.

This image from ESA Rosetta spacecraft is of 67P/Churyumov-Gerasimenko shows the diversity of surface structures on the comet nucleus.

This still from a sequence of images shows comet 67P/Churyumov-Gerasimenko moving against the background star field.

A 3D image shows what it would look like to fly over the surface of comet 67P/Churyumov-Gerasimenko. The image was generated by data collected by ESA Philae spacecraft during the decent to the spacecraft initial touchdown on the comet Nov. 12, 2014.

A composite image from a camera on ESA Rosetta mission Philae comet lander shows a solar array, with comet 67P/Churyumov-Gerasimenko in the background.

Image of the southern polar regions of comet 67P/Churyumov-Gerasimenko taken by Rosetta Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS on September 29, 2014, when the comet was still experiencing the long southern winter. http://photojournal.jpl.nasa.gov/catalog/PIA19969

Since its launch nearly 20 years ago, NASA and the European Space Agency’s Solar and Heliospheric Observatory has spotted 3000 comets. The mission’s The Large Angle and Spectrometric Coronagraph (LASCO) instrument blocks out the bright solar disk, making it easier to see the corona of plasma and dust around the Sun, normally only visible during solar eclipses. This instrument also provides a very large field of view of the region around the Sun. This visualization utilizes SOHO data from 1998 – 2010 and shows over 2000 comets. Comets that were first observed by SOHO carry no labels, and comets witnessed by not discovered by the spacecraft are represented with their labels. Trails on the comets are color coded based on family: yellow – unaffiliated comets, red – Kreutz group, green – Meyer group, blue – Marsden, cyan – Kracht, and magenta – Kracht 2.

The European Space Agency’s Rosetta mission concluded its study of comet 67P/Churyumov-Gerasimenko on Sept. 30, 2016. NASA’s planet-hunting Kepler spacecraft observed the comet during the final month of the Rosetta mission, while the comet was not visible from Earth. This animation is composed of images from Kepler of the comet. From Sept. 7 through Sept. 20, the Kepler spacecraft, operating in its K2 mission, fixed its gaze on comet 67P. From the distant vantage point of Kepler, the comet’s nucleus and tail could be observed. The long-range view from Kepler complements the closeup view of the Rosetta spacecraft, providing context for the high-resolution investigation Rosetta performed as it descended closer and closer to the comet. During the two-week period of study, Kepler took a picture of the comet every 30 minutes. The animation shows a period of 29.5 hours of observation from Sept. 17 thru Sept. 18. The comet is seen passing through Kepler’s field of view from top right to bottom left, as outlined by the diagonal strip. The white dots represent stars and other regions in space studied during K2’s tenth observing campaign. As a comet travels through space it sheds a tail of gas and dust. The more material that is shed, the more surface area there is to reflect sunlight. A comet’s activity level can be obtained by measuring the reflected sunlight. Analyzing the Kepler data, scientists will be able to determine the amount of mass lost each day as comet 67P travels through the solar system. An animation is available at http://photojournal.jpl.nasa.gov/catalog/PIA21072

The ESA/NASA Solar and Heliospheric Observatory has discovered more than 3000 doomed comets that have passed close to the sun.

Artist impression of the Rosetta orbiter at comet 67P/Churyumova-Gerasimenko. The image is not to scale.