[meteorite-list] Jupiter Pummeled, Leaving Bruise The Size of the Pacific Ocean

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 23 Jul 2009 16:31:55 -0700 (PDT)
Message-ID: <200907232331.n6NNVtFV008807_at_zagami.jpl.nasa.gov>

Media Relations
University of California-Berkeley

Contact: Robert Sanders
Phone: (510) 643-6998

21 July 2009

Jupiter pummeled, leaving bruise the size of the Pacific Ocean

BERKELEY -- Something slammed into Jupiter in the last few days, creating a
dark bruise about the size of the Pacific Ocean.

The bruise was noticed by an amateur astronomer on Sunday, July 19.
University of California, Berkeley, astronomer Paul Kalas took advantage of
previously scheduled observing time on the Keck II telescope in Hawaii to
image the blemish in the early morning hours of Monday, July 20. The
near-infrared image showed a bright spot in Jupiter's southern hemisphere,
where the impact had propelled reflective particles high into the relatively
clear stratosphere.

In visible light, the bruise appears dark against the bright surface of
Jupiter.

The observation made with the Keck II telescope marks only the second time
astronomers have seen the results of an impact on the planet. The first
collision occurred exactly 15 years ago, between July 16 and 22, 1994, when
more than 20 fragments of comet Shoemaker-Levy 9 collided with Jupiter.

The Shoemaker-Levy 9 (SL9) impact events were well-studied by astronomers,
including several from UC Berkeley, and many theories were subsequently
developed based on the observations.

"Now we have a chance to test these ideas on a brand new impact event," said
Kalas, who observed the aftermath of the new impact with the help of Michael
Fitzgerald of Lawrence Livermore National Lab and UCLA.

The astronomers decided to observe Jupiter after hearing that Australian
amateur astronomer Anthony Wesley had discovered the planet's new scar. They
read about it on the blog of UC Berkeley and SETI Institute astronomer
Franck Marchis (http://www.cosmicdiary.org/blogs/nasa/franck_marchis/).
Kalas, who is in Greece, consulted intensely with Fitzgerald and Marchis on
how best to observe the feature. Fitzgerald then performed the observations
with the help of Keck Observatory astronomer Al Conrad.

"The analysis of the shape and brightness of the feature will help in
determining the energy and the origin of the impactor," said Marchis. "We
don't see other bright features along the same latitude, so this was most
likely the result of a single asteroid, not a chain of fragments like for
SL9."

"The fact that (the feature) shows up so clearly means that it's associated
with high-altitude aerosols, as seen in the Shoemaker-Levy impacts," said
James Graham of UC Berkeley, who assisted with the new observations as well
as with observations taken during the SL9 event in 1994.

Mike Wong, a UC Berkeley researcher currently on leave at the Space
Telescope Science Institute in Baltimore, used the observations to calculate
that the scar is near the southern pole of Jupiter (305 W, 57 S in
planetographic coordinates) and that the impact covers a
190-million-square-kilometer area as big as the Pacific Ocean. Because of
the complex shape of the explosion, it is possible that tidal effects
fragmented the impactor -- a comet or asteroid -- shortly before it collided
with the planet.

The impact fell on the 15th anniversary of the SL9 impacts, but the
coincidences do not end there. Kalas' original plan was to search for a
previously detected, Jupiter-like planet around the star Fomalhaut. The star
is located roughly 25 light years from Earth in the direction of the
constellation Piscis Austrinus. Kalas showed previously that the planet,
dubbed Fomalhaut b, is bright, and one explanation for that brightness is
that it is suffering impacts just like Jupiter, he said.

Later this week, astronomers from UC Berkeley and around the world plan to
conduct high-resolution visible and ultraviolet observations of the impact
site using the Hubble Space Telescope's brand new Wide Field Camera 3.
Ground-based facilities including the W. M. Keck telescope will also use
adaptive optics to obtain much sharper infrared images of the impact's
aftermath. But the Keck images reported here will provide a crucial baseline
for measuring the spread of impact-related material, Wong said. No other
method exists to directly track the winds at these rarified levels of
Jupiter's atmosphere.

One of those planning to observe Jupiter with Keck is UC Berkeley astronomer
Imke de Pater, who was one of the leaders of the campus's SL9 observations
of Jupiter in 1994. Working with Conrad and Wong, she plans to observe
Jupiter on July 24 using a laser guide star with adaptive optics, analogous
to observations conducted in July 2006 and May 2008.

More information: Keck Observatory press release,
     http://keckobservatory.org/index.php/news/jupiters_adds_a_feature/

IMAGE CAPTIONS:

[Image 1:
http://www.berkeley.edu/news/media/download/2009/07/jupiter.jpg (608KB)]
The scar from the probably impact appeared July 19 in Jupiter's southern
hemisphere, and has grown to a size greater than the extent of the Pacific
Ocean. This infrared image taken with Keck II on July 20 shows the new
feature observed on Jupiter and its relative size compared to Earth.

Credit: Paul Kalas (UCB), Michael Fitzgerald (LLNL/UCB), Franck Marchis
(SETI Institute/UCB), James Graham (UCB)

[Image 2:
http://www.berkeley.edu/news/media/releases/2009/07/images/jupiter2.jpg
(34KB)]
False color image of the impact site in Jupiter's southern hemisphere.

Credit: Paul Kalas (UCB), Michael Fitzgerald (LLNL/UCB), Franck Marchis
(SETI Institute/UCB), James Graham (UCB)
Received on Thu 23 Jul 2009 07:31:55 PM PDT