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Jupiter's South Polar Region (SPR) was observed by James Webb Space Telescope/Mid‐Infrared Instrument in December 2022. We used the Medium Resolution Spectrometer mode to provide new information about Jupiter's South Polar stratosphere. The southern auroral region was visible and influenced the atmosphere in several ways: (a) In the interior of the southern auroral oval, we retrieved peak temperatures at two distinct pressure levels near 0.01 and 1 mbar, with warmer temperatures with respect to non‐auroral regions of 12 ± 2 K and 37 ± 4 K respectively. A cold polar vortex is centered at 65°S at 10 mbar. (b) We found that the homopause is elevated to 590−118+25${590}_{-118}^{+25}$km above the 1‐bar pressure level inside the auroral oval compared to 460−50+60${460}_{-50}^{+60}$km at neighboring latitudes and with an upper altitude of 350 km in regions not affected by auroral precipitation. (c) The retrieved abundance of C2H2shows an increase within the auroral oval, and it exhibits high abundances throughout the polar region. The retrieved abundance of C2H6increases toward the pole, without being localized in the auroral oval, in contrast with previous analysis (Sinclair et al., 2018, https://doi.org/10.1016/j.icarus.2017.09.016). We determined that the warming at 0.01 mbar and the elevated homopause might be caused by the flux of charged particles depositing their energy in the SPR. The 1‐mbar hotspot may arise from adiabatic heating resulting from auroral‐driven downwelling. The cold region at 10 mbar may be caused by radiative cooling by stratospheric aerosols. The differences in spatial distribution seem to indicate that the hydrocarbons analyzed are affected differently by auroral precipitation. James Webb Space Telescope/Mid‐Infrared instrument observed Jupiter's south polar region in December 2022. The instrument acquired spectroscopic data in the mid‐infrared part of the spectrum, which is sensitive to the temperature of the atmosphere and the chemical abundances. These observations revealed that within the auroral oval there are two regions of high temperatures located at two different altitudes. These are presumably caused by two different phenomena: direct heating from the incoming charged particles in the aurora at a height of 0.01 mbar and adiabatic heating in downdrafts at lower levels. A decrease in temperature was also observed as we approached the South Pole, probably caused by a cold polar vortex associated with stratospheric hazes. We found that the altitude of the homopause (the limit between the well‐mixed part of the atmosphere and the part where molecules are separated according their specific weight) is altered by the auroras, being up to 100 km higher in the auroral region. The atmospheric abundances of acetylene and ethane showed an enrichment of acetylene within the auroral oval, and of ethane at the pole, which may indicate that these molecules are not affected in the same way by the energy input of the aurora. The homopause is spatially variable within the polar region and highest within the auroral ovalThe atmosphere inside the Southern Auroral Oval at 1 and 0.01 mbar shows a warming compared with non‐auroral regionsThe C2H2abundance is enhanced inside the Southern Auroral Oval at 0.1 and 7 mbar, and C2H6shows an increase polewards The homopause is spatially variable within the polar region and highest within the auroral oval The atmosphere inside the Southern Auroral Oval at 1 and 0.01 mbar shows a warming compared with non‐auroral regions The C2H2abundance is enhanced inside the Southern Auroral Oval at 0.1 and 7 mbar, and C2H6shows an increase polewards

We observed Io with the James Webb Space Telescope (JWST) while the satellite was in eclipse, and detected thermal emission from several volcanoes. The data were taken as part of our JWST‐ERS program #1373 on 15 November 2022. Kanehekili Fluctus was exceptionally bright, and Loki Patera had most likely entered a new brightening phase. Spectra were taken with NIRSpec/IFU at a resolving power R≈ 2,700 between 1.65 and 5.3 µm. The spectra were matched by a combination of blackbody curves that showed that the highest temperature, ∼1,200 K, for Kanehekili Fluctus originated from an area ∼0.25 km2in size, and for Loki Patera this high temperature was confined to an area of ∼0.06 km2. Lower temperatures, down to 300 K, cover areas of ∼2,000 km2for Kanehekili Fluctus, and ∼5,000 km2for Loki Patera. We further detected the a1Δ ⇒ X3Σ−1.707 µm rovibronic forbidden SO emission band complex over the southern hemisphere, which peaked at the location of Kanehekili Fluctus. This is the first time this emission has been seen above an active volcano, and suggests that the origin of such emissions is ejection of SO molecules directly from the vent in an excited state, after having been equilibrated at temperatures of ∼1,500 K below the surface, as was previously hypothesized. We observed Io with JWST in November 2022 while the satellite was in Jupiter's shadow, and glowing volcanoes show up without being (partially) obscured by reflected sunlight. We detected the volcanoes Loki Patera and Kanehekili Fluctus; the latter was exceptionally bright, and Loki Patera had likely entered a new brightening phase. Both volcanoes show erupting lavas at temperatures of at least 1,200 K, originating at a vent of ∼0.25 km2in size for Kanehekili Fluctus and <0.1 km2for Loki Patera. In addition to lava, Kanehekili Fluctus spews out gases, and we detected, for the first time, SO emission at 1.707 μm right over the volcano. This is the first time this emission has been seen above an active volcano, and suggests that such emissions are produced by SO molecules immediately upon leaving the vent. James Webb Space Telescope observations detected an energetic eruption at Kanehekili Fluctus, and a new brightening event at Loki PateraThe erupting lavas have a temperature of at least 1,200 K over an area of ∼0.25 km2or lessWe detected, for the first time, a clear association of the 1.707 micron forbidden SO emissions with an active volcano James Webb Space Telescope observations detected an energetic eruption at Kanehekili Fluctus, and a new brightening event at Loki Patera The erupting lavas have a temperature of at least 1,200 K over an area of ∼0.25 km2or less We detected, for the first time, a clear association of the 1.707 micron forbidden SO emissions with an active volcano

The Mars 2020 Perseverance rover landed in Jezero crater on 18 February 2021. After a 100‐sol period of commissioning and the Ingenuity Helicopter technology demonstration, Perseverance began its first science campaign to explore the enigmatic Jezero crater floor, whose igneous or sedimentary origins have been much debated in the scientific community. This paper describes the campaign plan developed to explore the crater floor's Máaz and Séítah formations and summarizes the results of the campaign between sols 100–379. By the end of the campaign, Perseverance had traversed more than 5 km, created seven abrasion patches, and sealed nine samples and a witness tube. Analysis of remote and proximity science observations show that the Máaz and Séítah formations are igneous in origin and composed of five and two geologic members, respectively. The Séítah formation represents the olivine‐rich cumulate formed from differentiation of a slowly cooling melt or magma body, and the Máaz formation likely represents a separate series of lava flows emplaced after Séítah. The Máaz and Séítah rocks also preserve evidence of multiple episodes of aqueous alteration in secondary minerals like carbonate, Fe/Mg phyllosilicates, sulfates, and perchlorate, and surficial coatings. Post‐emplacement processes tilted the rocks near the Máaz‐Séítah contact and substantial erosion modified the crater floor rocks to their present‐day expressions. Results from this crater floor campaign, including those obtained upon return of the collected samples, will help to build the geologic history of events that occurred in Jezero crater and provide time constraints on the formation of the Jezero delta. The Mars 2020 Perseverance rover, along with the Ingenuity Helicopter technology demonstration, landed in Jezero crater, Mars on 18 February 2021. Here, we detail results from the first science campaign of the mission, the purpose of which was to explore the enigmatic Jezero crater floor. By the end of the campaign, Perseverance traversed more than 5 km, created seven abrasion patches, and sealed a total of nine samples and a witness tube for return to Earth. Analysis of the rocks in the crater floor revealed two distinct geologic formations, named the Máaz and Séítah formations. Both formations were determined to be igneous in origin, the former likely from a series of lava flows and the latter formed from a slowly cooling melt or magma body. The composition of the Máaz and Séítah formation rocks also indicate that they experienced significant alteration from water in the past, consistent with Jezero crater having once been filled with water. Results from Perseverance's Jezero crater floor campaign, including those obtained upon return of the collected samples to Earth, will help build the geologic history of Jezero crater and reveal its past habitability. The Máaz and Séítah formations are igneous, with Séítah representing olivine‐rich cumulates and Máaz representing separate lava flowsCrater floor rocks have been variably altered to produce carbonates and other alteration minerals during multiple aqueous episodesPost‐emplacement processes tilted these rocks near the Máaz‐Séítah contact, and erosion produced varied textures and olivine‐rich regolith The Máaz and Séítah formations are igneous, with Séítah representing olivine‐rich cumulates and Máaz representing separate lava flows Crater floor rocks have been variably altered to produce carbonates and other alteration minerals during multiple aqueous episodes Post‐emplacement processes tilted these rocks near the Máaz‐Séítah contact, and erosion produced varied textures and olivine‐rich regolith