Sky and Telescope - July 2016 - 10

News Notes
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JOHN MCKEON AND MARC DELCROIX

SOLAR SYSTEM I Impact on Jupiter?

A frame from Irish astro-imager John McKeon's video of Jupiter taken
March 17, 2016. He captured a momentary impact, lasting just 1 second,
as a bright spot on the planet's limb. The moon Europa is at left; Ganymede and Io are at right.

Something seems to have hit our solar system's largest planet.
Two amateur videos shot early on March 17th show a brief but
bright ﬂash on the edge of Jupiter's disk. Gerrit Kernbauer of
Mödling, Austria, ﬁrst called attention to the collision. He had
recorded Jupiter using an 8-inch f/5 reﬂector in so-so seeing. But
while reviewing his video 10 days later, he noticed a bright spot on
one edge of the planet's disk that lasted for about 1 second.
Two days later, Irish observer John McKeon posted a second
record of the ﬂash. McKeon had used an 11-inch SchmidtCassegrain telescope and ASI120MM camera in Swords, a Dublin
suburb. Crucially, he also used a near-infrared ﬁlter to reduce the
planet's brightness. He was making a 3½-hour-long time-lapse
video of Jupiter and its moons, "with a happy coincidence of the

impact in the second-to-last capture of the night."
Soon planetary imaging specialist Marc Delcroix obtained
the raw videos, processed them to bring out extra detail, and
reﬁned the circumstances of the ﬂash. He ﬁnds that the
brightening lasted just over 1 second and occurred at 281.1°° in
longitude and +12.4° in latitude (in System II coordinates, which
apply to cloud features away from the equator). But the timing is
oﬀ a bit: in Kernbauer's video the ﬂash began at 0:18:35 Universal Time, whereas in McKeon's the onset is 9 seconds later.
Despite the time mismatch, the event appears to be real.
Apparently the impacting object, be it an asteroid or comet, was
rather small. "Nobody sees any debris ﬁeld associated with that
part of the atmosphere," notes planetary scientist Glenn Orton
(Jet Propulsion Laboratory).
Apart from Comet Shoemaker-Levy 9's historic multiplehit crash in 1994, the most obvious impact observed on Jupiter
took place July 19, 2009, and it left a distinctly dark "powder
burn" in Jupiter's upper atmosphere, ﬁrst spotted by Australian
astro-imager Anthony Wesley (S&T: Nov. 2009, p. 34). That was
followed by three lesser strikes witnessed on June 3 and August
10, 2010, and on September 10, 2012. If evidence for March 17th's
impact holds up (which is likely), then it'll be the ﬁfth such
event recorded in the past decade.
The reported sightings are likely only a fraction of the full
number of hits the gas giant endures. In fact, we should be
seeing impacts on Jupiter rather often, according to a statistical
analysis published in the December 2013 issue of Astronomy &
Astrophysics. Ricardo Hueso (University of the Basque Country,
Spain) and his colleagues estimate that objects with diameters
of 5 to 20 meters, as the last decade's impactors likely were,
should collide with Jupiter anywhere from one to ﬁve times per
month. If so, scores have gone unseen.
■ J. KELLY BEATTY

MISSIONS I European-Russian ExoMars Heads to Red Planet
The ExoMars Trace Gas
Orbiter and Schiaparelli lander
left Earth on March 14th
aboard a Russian Proton rocket
launched from the Baikonur
Cosmodrome. A collaboration
between the European Space
Agency and Roscosmos (the
Russian space agency), ExoMars will spend seven months
cruising to the Red Planet.
10

Then, on October 16th, Schiaparelli will decouple from the
orbiter, touching down three
days later at Meridiani Planum, the same region being
explored by NASA's long-lived
Opportunity rover, just as the
spacecraft enters orbit.
The battery-powered lander
is only expected to last four
Martian days on the surface. A

July 2016 sky & telescope

successful touchdown would
represent a ﬁrst for any space
agency other than NASA and
the Soviet Union (its Mars 3
stopped working seconds after
arrival). Schiaparelli will test
entry and landing technology
for the European-Russian 2018
ExoMars rover.
Meanwhile, once it begins
science operations at the end

of 2017, the orbiter will search
out evidence for trace gases in
the Martian atmosphere. One
elusive mystery on Mars is
the source of methane, spotted both from Earth and by
NASA's Curiosity rover. ESA
and Roscosmos also plan to
use the orbiter as a communications relay for the 2018 rover.
■ DAVID DICKINSON

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Sky and Telescope - July 2016

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