tail visible in these images of
Jupiter is comparable to being
able to see a feature about the
size of Ireland from Jupiter’s
current distance of about 600
million kilometers (365 million
miles) from Earth.
the two agencies, NSF and NASA, working
together on such scientifically important
discoveries.”
The Gemini observations use special filters
that focus on specific colors of light that can
penetrate the upper atmosphere and clouds
of Jupiter. These images are sensitive to in-
creasing absorption by mixtures of methane
and hydrogen gas in Jupiter’s atmosphere.
“The Gemini images provide vertical sen-
sitivity from Jupiter’s cloud tops up to the
planet’s lower stratosphere,” said Orton.
The observations also employ adaptive op-
tics technology to significantly remove dis-
tortions due to the turbulence in the Earth’s
atmosphere and produce these extremely
high-resolution images. Specifically, the de-
January 2018 / 2017 Year in Review
In addition to images using
adaptive optics technology, a
parallel Gemini program head-
ed by Michael Wong of the
University of California, Berke-
ley, used a longer-wavelength
filter, for which adaptive optics
is not needed. To obtain these
data several images were made
with short exposures, and the
sharpest images were com-
bined in processing — an ap-
proach commonly called “lucky
imaging.” Images obtained with
this filter are mainly sensitive
to cloud opacity (blocks light)
in the pressure range of 0.5 to
3 atmospheres. “These obser-
vations trace vertical flows that
cannot be measured any other
way, illuminating the weather, climate, and
general circulation in Jupiter’s atmosphere,”
noted Wong. This image is shown in Figure 3.
Subaru Telescope also supplied simultane-
ous mid-infrared imaging with its COMICS
instrument — measuring the planet’s heat
output in a spectral region not covered by
Juno’s instrumentation, and producing data
on composition and cloud structure that
compliment both the Juno and Gemini ob-
servations. For example, they show a very
cold interior to the Great Red Spot that is
surrounded by a warm region at its periph-
ery, implying upwelling air in the center
that is surrounded by subsidence. They also
show a very turbulent region to the north-
west of the Great Red Spot. The Subaru im-
age is available here.
GeminiFocus
Figure 2.
Close-up images of the
Great Red Spot from
Gemini Near-InfraRed
Imager (NIRI) images
showing differences in
the interior structure of
this giant vortex with
altitude. The top image
was taken with a filter
at 2.275 microns that is
sensitive to particles at,
and above, pressures
of about 10 millibars
(about 1% of the pressure
at sea level on the
Earth) in Jupiter’s lower
stratosphere. It shows
that particles at this level
tend to increase toward
the center of this gigantic
vortex. The middle
image was taken with
a filter at 1.58 microns,
sensitive to virtually no
gaseous absorption,
and is sensitive to the
brightness of clouds,
very similar to visible
red light. Subtle oval-
shaped banded structure
going from the outside
to the interior can be
spotted in the image. The
difference between these
two images illustrates
major differences in the
dynamics of this vortex
with altitude. The bottom
image was taken with a
filter at 4.68 microns, and
shows bright thermal
emission from the deeper
atmosphere wherever
there is “clear sky” (low
cloud opacity in the
0.5-3 bar range). Top two
panels show data from
May 18, 2017, while the
bottom panel shows data
from January 11, 2017.
Credit: Gemini Observatory/
AURA/NSF/JPL-Caltech/NASA/
UC Berkeley
27