[meteorite-list] Mysterious Flash on Jupiter Left No Debris Cloud

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 16 Jun 2010 13:54:30 -0700 (PDT)
Message-ID: <201006162054.o5GKsUkr021658_at_zagami.jpl.nasa.gov>

June 16, 2010

Media Contact:
Ray Villard
Space Telescope Science Institute, Baltimore, Md.
+1 410-338-4514
villard at stsci.edu

Science Contact:
Amy Simon-Miller
NASA's Goddard Space Flight Center, Greenbelt, Md.
+1 410-286-6738
amy.simon at nasa.gov

MYSTERIOUS FLASH ON JUPITER LEFT NO DEBRIS CLOUD

Detailed observations made by NASA's Hubble Space Telescope have found
an answer to the flash of light seen June 3 on Jupiter. It came from a
giant meteor burning up high above Jupiter's cloud tops. The space
visitor did not plunge deep enough into the atmosphere to explode and
leave behind any telltale cloud of debris, as seen in previous Jupiter
collisions.

Astronomers around the world knew that something must have hit the
giant planet to unleash a flash of energy bright enough to be seen 400
million miles away. But they didn't know how deeply it penetrated into
the atmosphere. There have been ongoing searches for the "black-eye"
pattern of a deep direct hit.

The sharp vision and ultraviolet sensitivity of Hubble's Wide Field
Camera 3 were brought to bear on seeking out any trace evidence of the
aftermath of the cosmic collision. Images taken on June 7 -- just over
three days after the flash was sighted -- show no sign of debris above
Jupiter's cloud tops. This means that the object didn't descend
beneath the clouds and explode as a fireball. "If it did, dark sooty
blast debris would have been ejected and would have rained down onto
the cloud tops, and the impact site would have appeared dark in the
ultraviolet and visible images due to debris from an explosion," says
team member Heidi Hammel of the Space Science Institute in Boulder,
Colo. "We see no feature that has those distinguishing characteristics
in the known vicinity of the impact, suggesting there was no major
explosion and fireball."

Dark smudges marred Jupiter's atmosphere when a series of comet
fragments hit Jupiter in July 1994. A similar phenomenon occurred in
July 2009 when a suspected asteroid slammed into Jupiter. The latest
intruder is estimated to be only a fraction the size of these previous
impactors.

"We suspected for this 2010 impact there might be no big explosion
driving a giant plume, and hence no resulting debris field to be
imaged. There was just the meteor, and Hubble confirmed this," adds
Hammel, a veteran Jupiter observer of the 1994 string of impacts.

Australian amateur astronomer Anthony Wesley saw the flash at 4:31
p.m. (EDT) on June 3. He was watching a live video feed of Jupiter
from his telescope. In the Philippines, amateur astronomer Chris Go
confirmed that he had simultaneously recorded the transitory event on
video.

The two-second-long flash of light in the videos of Jupiter was
created by the same physics that causes a meteor (or "shooting star")
on Earth. A shock wave generated by ram pressure as the meteor speeds
into the planet's atmosphere heats the impacting body to a very high
temperature, and as the hot object streaks through the atmosphere, it
leaves behind a glowing trail of superheated atmospheric gases and
vaporized meteor material that rapidly cools and fades in just a few
seconds.

Though astronomers are largely uncertain about the rate of large
meteoroid impacts on the planets, the best guess for Jupiter is that
the smallest detectable events may happen as frequently as every few
weeks. "The meteor flashes are so brief they are easily missed, even
in video recordings, or perhaps misidentified as detector noise or
cosmic ray hits on imaging devices," says team member Mike Wong of the
University of California at Berkeley.

"It's difficult to even know what the current impact rates are
throughout the solar system. That's partly why we are so excited by
the latest impact. It illustrates a new capability that can be
exploited with increased monitoring of Jupiter and the other planets,"
says Amy Simon-Miller of NASA's Goddard Space Flight Center, the
principal investigator on the Jupiter observation.

As a bonus, the Hubble observations also allowed scientists to get a
close-up look at changes in Jupiter's atmosphere following the
disappearance of the dark Southern Equatorial Belt (SEB) several
months ago.

In the Hubble view, a slightly higher altitude layer of white ammonia
ice crystal clouds appears to obscure the deeper, darker belt clouds.
"Weather forecast for Jupiter's South Equatorial Belt: cloudy with a
chance of ammonia," Hammel says.

The team predicts that these ammonia clouds should clear out in a few
months, as it has done in the past. The clearing of the ammonia cloud
layer should begin with a number of dark spots like that seen by
Hubble along the boundary of the south tropical zone.

"The Hubble images tell us these spots are holes resulting from
localized downdrafts taking place. We often see these types of holes
when a change is about to occur," Simon-Miller says.

"The SEB last faded in the early 1970s. We haven't been able to study
this at this level of detail before," Simon-Miller adds. "The changes
of the last few years are adding to an extraordinary database on
dramatic cloud changes on Jupiter."

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Images and more information about the June 3, 2010, Jupiter impact:
* http://hubblesite.org/news/2010/20
* http://www.nasa.gov/hubble

The Hubble Space Telescope is a project of international cooperation
between NASA and the European Space Agency. NASA's Goddard Space
Flight Center manages the telescope. The Space Telescope Science
Institute (STScI) conducts Hubble science operations. STScI is
operated for NASA by the Association of Universities for Research in
Astronomy, Inc. in Washington, D.C.
Received on Wed 16 Jun 2010 04:54:30 PM PDT