GeminiFocus July 2017 | Page 12

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 ovalshaped 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 .
Image credit : Gemini Observatory / AURA / NSF / JPL-
Caltech / NASA / UC Berkeley
ground and space-based observations , and 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 increasing absorption by mixtures of methane and hydrogen gas in Jupiter ’ s atmosphere . “ The Gemini images provide vertical sensitivity from Jupiter ’ s cloud tops up to the planet ’ s lower stratosphere ,” said Orton .
The observations also employ adaptive optics technology to significantly remove distortions due to the turbulence in the Earth ’ s atmosphere and produce these extremely high-resolution images . Specifically , the detail 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 .
In addition to images using adaptive-optics technology , a parallel Gemini program headed by Michael Wong of the University of California , Berkeley , 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 combined in processing - an approach 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 observations 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 simultaneous 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 observations . For example , they show a very cold interior to the Great Red Spot that is surrounded by a warm region at its periphery , implying upwelling air in the center that is
10 GeminiFocus July 2017