[meteorite-list] Rosetta's Comet Wakes Up (67P/Churyumov-Gerasimenko)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 10 Mar 2014 08:39:39 -0700 (PDT)
Message-ID: <201403101539.s2AFddoq018132_at_zagami.jpl.nasa.gov>

http://www.mps.mpg.de/3261529/Rosetta_s-comet-wakes-up

Rosetta's comet wakes up

In new images recorded by ESO's Very Large Telescope comet Churyumov-Gerasimenko
appears brighter than expected.

Max Planck Institute
March 10, 2014

It's back! After comet 67P/Churyumov-Gerasimenko had disappeared behind
the Sun and out of the Earth's view last year in October, the target comet
of ESA's Rosetta mission can now be seen again. In the most recent image
obtained by researchers from the Max Planck Institute for Solar System
Research (MPS) in Germany and the European Southern Observatory (ESO)
with the help of ESO's Very Large Telescope on February 28th, 2014, the
comet presents itself brighter than expected for the nucleus alone. This
suggests that frozen ice is already beginning to vaporize and form a very
thin atmosphere. In August, the spacecraft Rosetta will rendezvous with
67P/Churyumov-Gerasimenko and accompany it on its journey around the Sun
until at least the end of 2015.

[Images]
Comet 67P/Churyumov-Gerasimenko as observed on Februaray 28th, 2014, with
the Very Large Telescope.

To obtain a measurable image of the comet from a distance of 740 million
kilometers, the scientists superposed several exposures taken at slightly
different times. Before, the images were shifted to compensate for the
comet's motion. The stars in the background therefore appear as broadly
smudged lines. Subtracting the starry background then revealed the comet:
a tiny dot in space.

For researchers, this tiny dot carries valuable information. Already
67P/Churyumov-Gerasimenko is approximately 50 percent brighter than in the
last images from October 2013. While the comet has moved another 50 million
kilometers closer to Earth in this time (and 80 million kilometers closer to
the Sun), the increase in brightness cannot be explained by the smaller
distance alone.

"The new image suggests that 67P is beginning to emit gas and dust at
a relatively large distance from the Sun", says Colin Snodgrass from the
MPS. This confirms a study presented by Snodgrass and his colleagues last
year in which they had compared the comet's brightness as recorded during
its previous orbits around the Sun. The calculations showed that already
in March 2014 its activity would be measurable from Earth.

In the coming months, the researchers will continue to monitor how the
comet's brightness develops in close collaboration with ESA. The data
will help to assess what conditions await Rosetta upon arrival in August.
Received on Mon 10 Mar 2014 11:39:39 AM PDT