SOFIA observations of variability in Jupiter’s Para-H2 distribution and subsurface emission characteristics of the Galilean Satellites

Imke de Pater, Leigh N. Fletcher, William T. Reach, Charles Goullaud, Glenn S. Orton, Michael H. Wong, Robert D. Gehrz

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


We observed Jupiter’s thermal emission with SOFIA/FORCAST in 2018 August and 2019 July. Both broad-band images (8–37 μm) and spectra (17–37 μm) were obtained. We used the shape of the Jovian spectra to determine the latitudinal distribution of temperatures and para-H2 in the upper troposphere, and compared this to similar data obtained in Fletcher et al. (2017). The two data sets were taken approximately half a Jovian year apart, the first (2014) during northern summer (Ls = 158°) and the second (2019) during southern summer (Ls = 304°). During both epochs the high northern latitudes are cooler than the south. Para-H2 is observed in sub-equilibrium at the equator and in super-equilibrium near the poles during all epochs. The largest difference between the two epochs is the detection of high-para-H2 content at high southern latitudes in 2019, in contrast to the earlier (2014) observations. This implies that the high-latitude para-H2 appears to vary over multi-year timescales. In addition to aiding in the calibration of and providing context to the Jovian spectra, the images were used to determine spectra of the four Galilean satellites. Over the 8–35 μm wavelength range the brightness temperatures of all four satellites drop with increasing wavelength. Although this is expected as longer wavelengths probe the satellites’ deeper, cooler layers, our data quantify the brightness temperature gradient with wavelength.

Original languageEnglish (US)
Article number226
JournalPlanetary Science Journal
Issue number6
StatePublished - Dec 2021

Bibliographical note

Funding Information:
We thank two anonymous referees for their help in improving this paper. This work was based on observations made with the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA), and was financially supported through SOF-06-0009 to the University of California, Berkeley. SOFIA is jointly operated by the Universities Space Research Association, Inc. (USRA), under NASA contract NNA17BF53C, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901 to the University of Stuttgart. We are grateful for all those involved in the telescope engineering, operations support and the flight crews. Fletcher is supported by a European Research Council Consolidator Grant (under the European Union’s Horizon 2020 research and innovation program, grant agreement No. 723890) at the University of Leicester. This research used the ALICE High Performance Computing Facility at the University of Leicester. R.D.G. was supported, in part, by the United States Air Force. Orton is supported by NASA using funds distributed to the Jet Propulsion Laboratory, California Institute of Technology, under contract 80NM0018D0004. Wong is grateful for the chance to fly aboard SOFIA OC6-J Flight 6.

Publisher Copyright:
© 2021. The Author(s). Published by the American Astronomical Society.


  • Jupiter (873)
  • Unified astronomy thesaurus concepts


Dive into the research topics of 'SOFIA observations of variability in Jupiter’s Para-H2 distribution and subsurface emission characteristics of the Galilean Satellites'. Together they form a unique fingerprint.

Cite this