Written by Guy Webster
NASA’s Jet Propulsion Laboratory
Pasadena, CA – The High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter captured views of comet C/2013 A1 Siding Spring while that visitor sped past Mars on Sunday (October 19th), yielding information about its nucleus.
The images are the highest-resolution views ever acquired of a comet coming from the Oort Cloud at the fringes of the solar system.
![These images were taken of comet C/2013 A1 Siding Spring by NASA's Mars Reconnaissance Orbiter on Oct. 19, 2014, during the comet's close flyby of Mars and the spacecraft. (NASA/JPL-Caltech/University of Arizona) These images were taken of comet C/2013 A1 Siding Spring by NASA's Mars Reconnaissance Orbiter on Oct. 19, 2014, during the comet's close flyby of Mars and the spacecraft. (NASA/JPL-Caltech/University of Arizona)](https://www.clarksvilleonline.com/wp-content/uploads/2014/10/Mars-Orbiter-Image-Shows-Comet-Nucleus-is-Small-480x321.jpg)
This comet’s flyby of Mars provided spacecraft at the Red Planet an opportunity to investigate from close range.
Images of comet Siding Spring from HiRISE are online at
http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18618
The highest-resolution of images of the comet’s nucleus, taken from a distance of about 86,000 miles (138,000 kilometers), have a scale of about 150 yards (138 meters) per pixel. Telescopic observers had modeled the size of the nucleus as about half a mile, or one kilometer wide.
However, the best HiRISE images show only two to three pixels across the brightest feature, probably the nucleus, suggesting a size smaller than half that estimate.
For more about HiRISE, visit:
For more about Mars Reconnaissance Orbiter, visit:
For more about comet Siding Spring, including other images of the comet, visit: