Figure 1.
A composite color infrared image of Jupiter
reveals haze particles over a range of altitudes, as
seen in reflected sunlight. The image was taken
using the Gemini North telescope’s Near-InfraRed
Imager (NIRI) on May 18, 2017, one day before
the Juno mission’s fifth close passage (“perijove”)
of the planet. The color filters cover wavelengths
between 1.69 to 2.275 microns and are sensitive to
pressures of 10 millibars to 2 bars. The Great Red
Spot (GRS) appears as the brightest (white) region
at these wavelengths, which are primarily sensitive
to high-altitude clouds and hazes near and above
the top of Jupiter’s convective region – revealing
that the GRS is one of the highest-altitude features
in Jupiter’s atmosphere. The features that appear
yellow/orange at Jupiter’s poles arise from the
reflection of sunlight from high-altitude hazes
that are the products of auroral-related chemistry
in the planet’s upper stratosphere.
Narrow spiral streaks that appear to lead into
the GRS or out of it from surrounding regions
probably represent atmospheric features being
stretched by the intense winds within the GRS, such as the hook-
like structure on its western edge (left side). Some are being
swept off its eastern edge (right side) and into an extensive
wave-like flow pattern; and there is even a trace of flow from
its north. Other features near the GRS include the dark block
and dark oval to the south and the north of the eastern flow
pattern, respectively, indicating a lower density of cloud and
haze particles in those locations. Both are long-lived cyclonic
circulations, rotating clockwise — in the opposite direction as
the counterclockwise rotation of the GRS. A prominent wave
pattern is evident north of the equator, along with two bright
ovals; these are anticyclones that appeared in January. Both
spacecraft orbiting the Earth (covering X-ray
through visible wavelengths) and ground-
based observatories (covering near-infrared
through radio wavelengths).
Next up: Juno’s closest approach to Jupi-
ter on July 11, 2017. “Gemini observations,
which are already underway for the July
flyby, are helping to guide our plans for
this passage,” said Orton. He added that the
types of light Gemini captures provides a
powerful glimpse into the layers of Jupiter’s
atmosphere, as well as a 3-dimensional view
into Jupiter’s clouds. Among the questions
July 2017
the wave pattern and the ovals may be associated with an
impressive upsurge in stormy activity that has been observed
in these latitudes this year. Another bright anticyclonic oval is
seen further north. Juno may pass over these ovals during its
July 11th closest approach. High hazes are evident over both
polar regions with much spatial structure that has never been
seen quite so clearly in ground-based images, with substantial
variability in their spatial structure. The central wavelengths
and colors assigned to the filters are:1.69 microns (blue), 2.045
microns (cyan), 2.169 microns (green), 2.124 microns (yellow),
and 2.275 microns (red).
Image credit: Gemini Observatory/AURA/NSF/JPL-Caltech/NASA
Juno is investigating include poorly under-
stood planetary-scale atmospheric waves
south of the equator. “We aren’t sure if these
waves might be seen at higher latitudes,”
said Orton. “If so it might help us understand
phenomena in Jupiter’s circulation that are
quite puzzling.”
“Wow — more remarkable images from the
adaptive optics system at Gemini!” said Chris
Davis, Program Officer for Gemini at the Na-
tional Science Foundation (NSF), one of five
agencies that operate the observatory. “It’s
great to see this powerful combination of
GeminiFocus
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