[meteorite-list] Comet Siding Spring Seen Next to Mars (Hubble Space Telescope)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 23 Oct 2014 12:23:39 -0700 (PDT)
Message-ID: <201410231923.s9NJNdJt003196_at_zagami.jpl.nasa.gov>

     
October 23, 2014
     
CLOSE ENCOUNTERS: COMET SIDING SPRING SEEN NEXT TO MARS

This composite NASA Hubble Space Telescope Image captures the positions of
comet Siding Spring and Mars in a never-before-seen close passage of a comet
by the Red Planet, which happened at 2:28 p.m. EDT October 19, 2014. The
comet passed by Mars at approximately 87,000 miles (about one-third of the
distance between Earth and the Moon). At that time, the comet and Mars were
approximately 149 million miles from Earth.

The comet image shown here is a composite of Hubble exposures taken between
Oct. 18, 8:06 a.m. EDT to Oct. 19, 11:17 p.m. EDT. Hubble took a separate
photograph of Mars at 10:37 p.m. EDT on Oct. 18.

The Mars and comet images have been added together to create a single picture
to illustrate the angular separation, or distance, between the comet and Mars
at closest approach. The separation is approximately 1.5 arc minutes, or
one-twentieth of the angular diameter of the full Moon. The background
starfield in this composite image is synthesized from ground-based telescope
data provided by the Palomar Digital Sky Survey, which has been reprocessed
to approximate Hubble's resolution. The solid icy comet nucleus is too
small to be resolved in the Hubble picture. The comet's bright coma, a
diffuse cloud of dust enshrouding the nucleus, and a dusty tail, are clearly
visible.

This is a composite image because a single exposure of the stellar
background, comet Siding Spring, and Mars would be problematic. Mars is
actually 10,000 times brighter than the comet, and so could not be properly
exposed to show detail in the Red Planet. The comet and Mars were also moving
with respect to each other and so could not be imaged simultaneously in one
exposure without one of the objects being motion blurred. Hubble had to be
programmed to track on the comet and Mars separately in two different
observations.

The images were taken with Hubble's Wide Field Camera 3.

Felicia Chou
Headquarters, Washington
202-358-0257
felicia.chou at nasa.gov
Received on Thu 23 Oct 2014 03:23:39 PM PDT