The Temporal Brightening of Uranus' Northern Polar Hood From HST/WFC3 and HST/STIS Observations

James, Arjuna; Irwin, Patrick G. J.; Dobinson, Jack; Wong, Michael H.; Tsubota, Troy K.; Simon, Amy A.; Fletcher, Leigh N.; Roman, Michael T.; Teanby, Nick A.; Toledo, Daniel; Orton, Glenn S.

doi:10.1029/2023je007904

Cited by 3 publications

(1 citation statement)

References 35 publications

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“… 2019b ; James et al. 2023 ), as seen in a series of H-band (1.6-μm) images from 1997 through 2015. The polar cap feature swaps hemispheres before and after the equinox.…”

Section: Spatial Variation In the Uranus Atmospherementioning

confidence: 99%

Multiple Probe Measurements at Uranus Motivated by Spatial Variability

Wong,

Rowe-Gurney,

Markham

et al. 2024

Space Sci Rev

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A major motivation for multiple atmospheric probe measurements at Uranus is the understanding of dynamic processes that create and maintain spatial variation in thermal structure, composition, and horizontal winds. But origin questions—regarding the planet’s formation and evolution, and conditions in the protoplanetary disk—are also major science drivers for multiprobe exploration. Spatial variation in thermal structure reveals how the atmosphere transports heat from the interior, and measuring compositional variability in the atmosphere is key to ultimately gaining an understanding of the bulk abundances of several heavy elements. We review the current knowledge of spatial variability in Uranus’ atmosphere, and we outline how multiple probe exploration would advance our understanding of this variability. The other giant planets are discussed, both to connect multiprobe exploration of those atmospheres to open questions at Uranus, and to demonstrate how multiprobe exploration of Uranus itself is motivated by lessons learned about the spatial variation at Jupiter, Saturn, and Neptune. We outline the measurements of highest value from miniature secondary probes (which would complement more detailed investigation by a larger flagship probe), and present the path toward overcoming current challenges and uncertainties in areas including mission design, cost, trajectory, instrument maturity, power, and timeline.

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“… 2019b ; James et al. 2023 ), as seen in a series of H-band (1.6-μm) images from 1997 through 2015. The polar cap feature swaps hemispheres before and after the equinox.…”

Section: Spatial Variation In the Uranus Atmospherementioning

confidence: 99%

Multiple Probe Measurements at Uranus Motivated by Spatial Variability

Wong,

Rowe-Gurney,

Markham

et al. 2024

Space Sci Rev

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Dynamics and clouds in planetary atmospheres from telescopic observations

Sánchez-Lavega,

Irwin,

García Muñoz

2023

Astron Astrophys Rev

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This review presents an insight into our current knowledge of the atmospheres of the planets Venus, Mars, Jupiter, Saturn, Uranus and Neptune, the satellite Titan, and those of exoplanets. It deals with the thermal structure, aerosol properties (hazes and clouds, dust in the case of Mars), chemical composition, global winds, and selected dynamical phenomena in these objects. Our understanding of atmospheres is greatly benefitting from the discovery in the last 3 decades of thousands of exoplanets. The exoplanet properties span a broad range of conditions, and it is fair to expect as much variety for their atmospheres. This complexity is driving unprecedented investigations of the atmospheres, where those of the solar systems bodies are the obvious reference. We are witnessing a significant transfer of knowledge in both directions between the investigations dedicated to Solar System and exoplanet atmospheres, and there are reasons to think that this exchange will intensity in the future. We identify and select a list of research subjects that can be conducted at optical and infrared wavelengths with future and currently available ground-based and space-based telescopes, but excluding those from the space missions to solar system bodies.

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Modelling the seasonal cycle of Uranus’s colour and magnitude, and comparison with Neptune

Irwin,

Dobinson,

James

et al. 2023

Monthly Notices of the Royal Astronomical Society

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We present a quantitative analysis of the seasonal record of Uranus’s disc-averaged colour and photometric magnitude in Strömgren b and y filters (centred at 467 and 551 nm, respectively), recorded at the Lowell Observatory from 1950 to 2016, and supplemented with HST/WFC3 observations from 2016 to 2022. We find that the seasonal variations of magnitude can be explained by the lower abundance of methane at polar latitudes combined with a time-dependent increase of the reflectivity of the aerosol particles in layer near the methane condensation level at 1 – 2 bar. This increase in reflectivity is consistent with the addition of conservatively scattering particles to this layer, for which the modelled background haze particles are strongly absorbing at both blue and red wavelengths. We suggest that this additional component may come from a higher proportion of methane ice particles. We suggest that the increase in reflectivity of Uranus in both filters between the equinoxes in 1966 and 2007, noted by previous authors, might be related to Uranus’s distance from the Sun and the production rate of dark photochemical haze products. Finally, we find that although the visible colour of Uranus is less blue than Neptune, due to the increased aerosol thickness on Uranus, and this difference is greatest at Uranus’s solstices, it is much less significant than is commonly believed due to a long-standing misperception of Neptune’s ‘true’ colour. We describe how filter-imaging observations, such as those from Voyager-2/ISS and HST/WFC3, should be processed to yield accurate true colour representations.

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The Temporal Brightening of Uranus' Northern Polar Hood From HST/WFC3 and HST/STIS Observations

Cited by 3 publications

References 35 publications

Multiple Probe Measurements at Uranus Motivated by Spatial Variability

Multiple Probe Measurements at Uranus Motivated by Spatial Variability

Dynamics and clouds in planetary atmospheres from telescopic observations

Modelling the seasonal cycle of Uranus’s colour and magnitude, and comparison with Neptune

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