The JWST-Jupiter 2026 Campaign: Stripes, Vortices, and Auroras

Jupiter’s large angular size, brightness, and rapid rotation made it an ideal test for JWST observations during the first cycle of science operations (2022-23).  A combination of guaranteed time and early-release science programmes revealed new insights into Jupiter’s jet streams [1], auroras [2], low-latitude ionosphere [3], polar chemistry [4], and the vertical structure of the Great Red Spot [5, 6].  However, spectroscopic mapping coverage remained limited, due to the small fields-of-view of JWST’s integral field spectrometers (3-6”) compared to Jupiter’s diameter (~45”).  We addressed this via a trio of Cycle-4 programmes in February 2026, coordinating a campaign including NIRCam (1-5 µm imaging), NIRSpec/IFU (1.8-5.3 µm spectroscopy) and MIRI/MRS (4.9-28.5 µm spectroscopy), combined with amateur observers (providing visible-light context), professional observatories (VLT), and overlapping with Jupiter flybys by NASA’s Juno mission.  This presentation provides a first look at the dataset acquired in 2026.

JWST Observations:  GO6840 (14hrs, February 21-22, 2026, PI: Wong) acquired a 6-tile NIRSpec/IFU mosaic of Oval BA, Jupiter’s second-largest anticyclone, followed by two sets of NIRCam global imaging (spaced ~10 hours apart for tracking of cloud features), and followed by a 3-tile mosaic of Oval BA with MIRI/MRS.  GO8173 (16hrs, February 20, 2026) acquired MIRI/MRS observations of Jupiter’s poles and mid-IR auroral emissions, intended to map exogenous species provided to Jupiter’s stratosphere, focussing on the evolution of stratospheric H₂O, CO₂ and HCN that were initially delivered by comet Shoemaker-Levy 9 in 1994.  These were combined with GO6865 (24hrs, February 27-28, PI: Fletcher), which acquired a pole-to-pole MIRI/MRS scan as Jupiter rotated (13 distinct pointings), providing JWST’s first “global” map of 3D temperatures and gaseous composition.  These were scheduled to be as close as possible to Juno’s 81st perijove (February 25, 2026) to enable comparison of temperatures and composition with Juno’s close-in remote sensing and radio occultations.  All JWST spectroscopic data have been reduced via a custom pipeline [7] that reduces the effects of saturation, cleans artefacts from flat-fielding and cube-building phases, and then maps the data using PlanetMapper [8].

Amateur Support:  Interpretation of the JWST data will benefit significantly from a world-wide campaign of ground-based observations acquired throughout February 2026, revealing how the atmospheric phenomena observed in the infrared shifted and evolved during this period.  These global-scale visible-light images were collected through repositories like the Planetary Virtual Observatory and Laboratory (PVOL, http://pvol2.ehu.eus/pvol2/), the Association of Lunar and Planetary Observers (ALPO, https://alpo-astronomy.org/), or the ALPO-Japan site (https://alpo-j.sakura.ne.jp/indexE.htm), and then reprojected into maps via WinJUPOS. 

Global MIRI Results – Belts, Zones, Auroras:  The combined dataset reveals Jupiter’s banded structure from pole to pole, with spectroscopic inversions deriving 3D temperatures in the troposphere and stratosphere; tropospheric volatiles (NH₃, H₂O), clouds, and disequilibrium species (PH₃, AsH₃, CO); stratospheric hydrocarbons (CH₄ and its derivatives) and exogenic species (CO₂, H₂O, HCN).  North-south temperature contrasts are largest at the peaks of the zonal winds, confirming vertical windshear on the east-west flows.  Auroral heating is evident over both poles, including diffuse warmth within the northern oval (observed via CH₄ emission), and intriguing observations of a distinct auroral arc at 10.5 µm (ethylene emission).  The zonal temperature field will be compared to (i) recent Juno ratio occultation measurements [9] and (ii) the most recent space-based infrared thermal maps from Cassini/CIRS in 2000 [10].  The tropospheric composition (particularly NH₃, PH₃, and H₂O) will be used to search for robust evidence of rising and falling motions on the scale of Jupiter’s belts and zones.

Regional MIRI Results – Rifts, Storms, Vortices:  Despite the small field-of-view of MIRI/MRS, there is significant structure observed in each tile, including rifting, plumes and hotspots (dark formations) within the North Equatorial Belt; discrete white spots and wave patterns in the North-North Temperate Domain; Folded Filamentary Structure at southern high latitudes; and the internal structure of cyclonic segments (elongated brown features) in the South Temperate Belt. In addition, the mosaic of Oval BA captured several Anticyclonic White Ovals (A2 and A3) in the South-South Temperate Belt, meaning that we now have spectroscopic maps of three classes of anticyclones, from the largest (the Great Red Spot), to the intermediate-sized Oval BA, to the smaller white ovals.  Preliminary inspection reveals that the width of Oval BA changes with altitude in the troposphere, though spectral inversions are needed to disentangle thermal and aerosol effects. MIRI will allow us to indirectly measure 3D windshear over these ovals to understand how their peripheral winds change with altitude, to be compared to NIRCam’s direct windshear measurements (NIRCam has sensitivity to high-altitude haze features above the anticyclone’s main cloud deck).

By combining these three independent programmes (all acquired within a few days of one another) with ground-based context imaging, we provide the most comprehensive JWST view of Jupiter’s atmospheric dynamics and chemistry to date. 

 

References:  [1] Hueso et al., 2023, Nature Astronomy (10.1038/s41550-023-02099-2); [2] Nichols et al., 2025, Nature Communications (10.1038/s41467-025-58984-z); [3] Melin et al., 2023, Nature Astronomy (10.1038/s41550-024-02305-9); [4] Rodriguez-Ovalle et al., 2024, Astronomy & Astrophysics (10.1051/0004-6361/202451453); [5] Harkett et al., 2024, JGR: Planets (10.1029/2024JE008415); [6] Biagiotti et al., 2025, Astronomy & Astrophysics (10.1051/0004-6361/202554552); [7] King et al., 2023, RNAAS (10.3847/2515-5172/ad045f); [8] King et al., 2023, Journal of Open Source Software (10.21105/joss.05728); [9] Smirnova et al., 2026, Astronomy & Astrophysics (10.1051/0004-6361/2025568196); [10] Fletcher et al., 2016, Icarus, (10.1016/j.icarus.2016.06.008).