JWST Creates 3D Map of Uranus, Finds Exomoon Candidate
The James Webb Space Telescope has produced the first-ever 3D map of Uranus's atmosphere, revealing powerful auroras and unexpected cooling patterns. In separate research, astronomers report strong evidence for a candidate exomoon orbiting a planet outside our solar system. A new data analysis framework called Tempawral is also enabling more detailed study of exoplanet weather.
- The 3D map of Uranus was created using the James Webb Space Telescope's Near-Infrared Spectrograph (NIRSpec) during a continuous observation period of about 15 hours, which covers nearly a full Uranian day. The map charts temperature and ion density up to 3,100 miles (5,000 km) above the planet's cloud tops. - The new data confirms a long-term cooling trend in Uranus's upper atmosphere, a phenomenon that has been tracked by ground-based telescopes for more than three decades. This cooling is thought to be linked to long-term changes in the solar wind interacting with the planet's unique magnetosphere. - Uranus's magnetic field is highly unusual; it is tilted at 60 degrees from its rotational axis and is offset from the planet's center. This causes its auroras to appear in the planet's middle regions rather than near the poles as they do on Earth. - To date, there are zero confirmed exomoons, as their small size makes them incredibly difficult to detect. Astronomers primarily search for them by looking for transit timing variations (TTVs), where an exomoon's gravitational pull causes its host planet to speed up or slow down slightly in its orbit. - One of the most-studied previous exomoon candidates, discovered in 2018, is a potential Neptune-sized moon orbiting the planet Kepler-1625b, which is located about 8,000 light-years from Earth. - The Tempawral framework is a new data-driven model for quantitatively studying atmospheric variability, such as clouds and storms, on exoplanets and brown dwarfs. It analyzes the full dataset from time-series spectra to recover details like inhomogeneous cloud coverage and changing chemical abundances. - Researchers validated Tempawral by applying it to JWST observations of a highly variable brown dwarf, where it successfully identified a temperature perturbation of about 300 Kelvin and variations in water, carbon monoxide, and iron hydride.
