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 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).
Credit: Gemini Observatory/AURA/NSF/JPL-Caltech/NASA
26
from spacecraft orbiting the Earth (cover-
ing X-ray through visible wavelengths) and
ground-based observatories (covering near-
infrared through radio wavelengths). “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.”
Orton 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 Juno is investigating
include poorly understood planetary-scale
atmospheric waves south of the equator. “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
ground and space-based observations, and
GeminiFocus
January 2018 / 2017 Year in Review