Plate #tectonics represents a defining framework of modern #geoscience, accounting for large-scale features on Earth’s surface, such as mountains and valleys, as well as the processes that shape them, like volcanoes and earthquakes.

Present-day plate tectonics have not been observed on any other world in the solar system, and evidence of past activity on planets such as #Mars and #Venus is circumstantial.

Perhaps the best case for extraterrestrial plate tectonics is found in the floating ice shell of #Jupiter’s #moon #Europa.

The plate tectonics on Europa differs from its Earthly analog. It is spatially widespread; it is regionally confined rather than globally connected; it occurs intermittently and is not happening now; and during past activity, plates drifted limited distances of between 10 and 100 kilometers.

#planets
https://eos.org/research-spotlights/europas-plate-tectonic-activity-is-unlike-earths

Paper by Collins et al. (2022):
https://doi.org/10.1029/2022JE007492

An exoplanetary system about 116 light-years from Earth could flip the script on how #planets form.

Four planets orbit LHS 1903 — a red dwarf #star, the most common type of star in the #universe — and are arranged in a peculiar sequence.

The innermost #planet is rocky, while the next two are gaseous, and then, unexpectedly, the outermost planet is also rocky.

This arrangement contradicts a pattern commonly seen across the galaxy and in our own solar system, where the rocky planets ( #Mercury, #Venus, #Earth and #Mars) orbit closer to the sun and the gaseous ones ( #Jupiter, #Saturn, #Uranus and #Neptune) are farther away.

Astronomers suspect this common pattern arises because planets form within a disk of gas and dust around a young star, where temperatures are much higher close to the celestial body.

In these inner regions, volatile compounds such as water and carbon dioxide are vaporized while only materials that can withstand extreme heat — such as iron and rock-forming minerals — can clump together into solid grains. The planets that form there are therefore primarily rocky.

A discovery of a planet breaking this pattern is telling about anomalies in the common formation process.

#exoplanets #astronomy
https://www.ksl.com/article/51447598/astronomers-detect-a-solar-system-they-say-should-not-be-possible