NASA In Brief -- Hubble captures comet flyby

Hubble's composite of the flyby. Image: NASA.
Hubble's composite of the flyby. Image: NASA.

     The comet Siding Spring recently made a close flyby of Mars, and thanks to the Hubble Space Telescope, it was captured on camera.

     On Oct. 19, the comet was approximately 87,000 miles from Mars – that’s one-third the distance between Earth and the moon. At that time, the comet and Mars were about 149 million miles from Earth, according to NASA.
     The Hubble Space Telescope took a composite of images Oct. 18 -19 that shows the encounter.
     The Mars and comet images have been added together to create a single picture to illustrate the distance between the comet and Mars at the closest approach, NASA explains. The solid icy comet nucleus is too small to be seen in the Hubble picture, but the comet’s bright coma, a diffuse cloud of dust enshrouding the nucleus, and a dusty tail are clearly visible.
     A composite image was created because Mars actually is 10,000 times brighter than the comet, and thus the picture could not be properly exposed to show detail in the red planet. The comet and Mars also were moving with respect to each other and could not be shown simultaneously in one exposure without one of the objects being motion blurred. Hubble had to be programmed to track  the comet and Mars separately in two different observations.
     NASA used its extensive fleet of science assets, particularly those orbiting and roving Mars, to study this once-in-a-lifetime comet flyby.  

     INTERNET HARASSMENT COMMON:  Sometimes it is name-calling or bullying. Other times, it is more threatening behavior. Whatever the description, harassment has become common on the Internet, according to an Oct. 22 report on the Pew Research Center website.
     A center study finds that 40 percent of adults have experienced harassment online. A larger number – 73 percent – have seen someone else harassed. See the study here.

     Compiled from NASA and Pew Research Center reports.


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