NASA Astronomy Picture of the Day Collection

The Iron Tail of Comet McNaught

Outstanding in planet Earth's sky [ http://www.spacewea…gallery_mcnaught_pag e23.php ] early this year, Comet McNaught [ http://en.wikipedia…] is captured in this view from the STEREO [ http://stereo.gsfc.…] A spacecraft. McNaught's coma [ http://www.nasa.gov…] is so bright, it blooms [ http://www.cs.duke.…faq.html#blooming ] into the long horizontal stripe at the bottom of the field. Brilliant Venus, near the top left corner, also produces a severe horizontal blemish in the digital image. But the sensitive camera does accurately record the striations in McNaught's famous dust tail [ http://antwrp.gsfc.…] along a region stretching over 30 million kilometers toward the top right of the field of view. A separate, fainter, arching tail just to the left of the dust tail was initially thought to be an example of a common ion tail [ http://www.ifa.hawa…], formed by electrically charged atoms [ http://www.chem4kid…] carried away from the comet by the solar wind [ http://www.phy6.org…]. However, detailed [ http://www.swissedu…] modeling indicates that tail is actually due to neutral iron atoms pushed out by the pressure of sunlight [ http://www.phy6.org…] -- the first ever detected neutral iron tail from a comet. The iron atoms are thought to originate in dust grains [ http://stardust.jpl…] from the comet nucleus [ http://antwrp.gsfc.…] that contain the iron-sulfur mineral troilite [ http://www.mindat.o…] (FeS).

M. Fulle, F. Leblanc (INAF) et al. [ http://www.swissedu…], SECCHI [ http://secchi.nrl.n…] / STEREO [ http://stereo.gsfc.…], NASA [ http://www.nasa.gov/]

Hawaii

Venus

Goddard Space Flight Center (GSFC)

Jet Propulsion Laboratory (JPL)

Earth

STEREO

COMETS

Venus

Stardust

SECCHI

comet

http://antwrp.gsfc.…

SPD-APOD-ap070504