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Hiʻiaka is the largest moon of the distant dwarf planet Haumea. Here, the authors report the first multi-chord stellar occultations of Hiʻiaka, revealing its size, shape, and density, suggesting an origin from Haumea’s icy mantle.

The MIRI spectrometer onboard JWST measured Pluto and Charon’s infrared emissions separately, uncovering surface properties and revealing that Pluto’s haze plays a key role in controlling the atmospheric temperature.

JWST and Keck II spectral observations of Saturn’s moon Titan reveal methyl (CH₃) as well as non-local thermodynamic equilibrium emission bands of CO and CO₂. Imaging shows clouds in Titan’s northern hemisphere at several epochs, with some appearing to evolve in altitude.

JWST/NIRSpec spectra are used to analyse the surfaces of Centaurs, revealing two main compositions: those with refractory materials and water ice and those rich in carbon-based materials. Strong surface weathering due to thermal processing may be responsible.

Due to the limited wavelength coverage of measurements to date, some aspects of the composition of Pluto’s largest moon, Charon, remain unresolved. Here, the authors detect carbon dioxide and hydrogen peroxide on the surface of Charon’s northern hemisphere using JWST data.

The near-infrared spectrometer onboard JWST has detected CO₂ and CO ices on 56 and 29 trans-Neptunian objects, respectively, indicating two dominant compositional types among them. These compositional differences suggest varied formation regions in the protoplanetary disk.

The icy surface compositions, as revealed by JWST, of small bodies beyond the orbit of Neptune can be classified into three groups that can be related to the ice retention lines in the early Solar System, possibly before the planets migrated.

Very-high-energy γ-rays observed ten hours after the prompt emission of the γ-ray burst 180720B can be attributed to either an inverse Compton or an extreme synchrotron process.

Observations of the radio galaxy Centaurus A at teraelectronvolt energies resolve its large-scale jet and favour electron synchrotron processes as the source of its X-ray emission.

An angular extension at gamma-ray energies of 52 arcseconds is detected for the Crab nebula, revealing the emission region of the highest-energy gamma rays; simulations of the electromagnetic emission provide a non-trivial test of our understanding of particle acceleration in the Crab nebula.

Deep γ-ray observations of the Galactic Centre with arcminute angular resolution show traces of petaelectronvolt protons within the central ten parsecs of our Galaxy; the accelerator of these particles could have provided a substantial contribution to Galactic cosmic rays in the past.