Astronomy is often presented as the study of distant stars, galaxies and planets. Yet modern observational astronomy increasingly resembles materials science and thermodynamics on a planetary scale. Spectroscopy allows researchers to determine the chemical composition, temperature and physical characteristics of objects that cannot be sampled directly.

The James Webb Space Telescope (JWST) has accelerated this capability substantially because its infrared instruments can investigate molecular signatures associated with planetary atmospheres and surfaces.

A striking 2026 example is the rocky exoplanet LHS 3844 b. JWST mid-infrared spectroscopy provided evidence that its surface is dark and low in silica, consistent with basaltic or olivine-rich materials. The observations also provided constraints on surface grain characteristics and atmospheric gases.

This type of observation demonstrates an important scientific connection between planetary science and materials science. Minerals absorb and emit electromagnetic radiation according to their chemical composition, crystal structure and physical state. Consequently, spectral measurements can provide indirect information about geological materials located many light-years away.

JWST has also demonstrated how atmospheric spectroscopy can reveal planetary dynamics. Observations of the ultrahot Jupiter WASP-121 b detected asymmetric transit signals associated with the planet's rotation and changing atmospheric regions. The researchers observed variations in carbon monoxide and water absorption as different parts of the atmosphere rotated into view.

The same principle can be applied to planetary formation. JWST observations of the HR 8799 system detected multiple molecules, including water, carbon monoxide, methane, carbon dioxide and hydrogen sulfide, in three giant planets. Their atmospheric compositions indicate substantial enrichment in heavy elements and provide evidence about the role of solid material during giant-planet formation.

In another 2026 development, astronomers identified Beta Pictoris d, a third giant planet in the Beta Pictoris system. The discovery was supported by observations from JWST and ground-based facilities, providing another opportunity to study planetary architecture and atmospheric chemistry.

These discoveries highlight an increasingly interdisciplinary reality: planetary astronomy is also a form of remote materials characterisation.

The future of exoplanet science may therefore depend increasingly on combining astronomy, spectroscopy, thermodynamics, atmospheric chemistry, mineral physics and computational modelling to reconstruct the physical nature of worlds that cannot be visited.

References:

• Nature Astronomy (2026), “The dark and featureless surface of rocky exoplanet LHS 3844 b from JWST mid-infrared spectroscopy.”

• Ahrer et al., Nature Astronomy (2026), WASP-121 b atmospheric observations.

• Nature Astronomy (2026), HR 8799 planetary composition study.

• NASA Webb Science, Beta Pictoris d discovery.