Eggshell planet

An eggshell planet is a type of exoplanet characterized by its ultra-thin outer brittle layer and minimal topography. The term was introduced in scientific discussions to describe a subset of rocky exoplanets with specific geological and tectonic characteristics. These planets pose questions regarding their potential habitability due to the unlikelihood of them having plate tectonics.^[1][2][3]

Characteristics

The defining characteristic of an eggshell planet is its exceptionally thin lithosphere. The lithosphere of a planet is the rigid outermost shell, and its thickness can influence various geological processes, including the formation of mountains and plate tectonics. The thickness of the lithosphere is determined by a myriad of factors including the planet's size, interior temperature, and composition.^[1][4][5]

While plate tectonics is considered essential for maintaining Earth's habitability through temperature regulation, eggshell planets are thought to lack this process. This lack of tectonic activity is significant because plate tectonics is believed to be crucial for a planet's long-term habitability.^[1][4]

Discovery and research

Eggshell planets became a topic of interest following a series of studies examining the variety of exoplanets. Paul Byrne, an associate professor in the Department of Earth and Planetary Sciences at Washington University in St. Louis and a faculty fellow of the McDonnell Center for the Space Sciences, conducted the studies with his team.^[6] Through extensive modeling, Byrne and his team ran thousands of simulations to understand the parameters affecting the lithospheric thickness of rocky exoplanets.^[7][8]

Their research identified surface temperature as the primary determinant of the lithosphere's thickness. Other influential factors include planetary mass, distance from its host star, and age. As per their models, planets that are small, old, or distant from their star are likely to possess thick, rigid lithospheres. However, under certain conditions, some planets might have lithospheres only a few kilometers thick, leading to the "eggshell" designation.^[8][3]

These planets may bear similarities to specific regions on Venus, known for its vast lava plains and minimal high-standing terrain due to its scorching surface temperatures resulting in a thin lithosphere.^[7][8]

Potential habitability

The primary concern regarding eggshell planets is their suitability for life. As these planets are believed to lack plate tectonics—a process that might be essential for a rocky planet's long-term habitability—their capacity to support life becomes questionable. While the research is still ongoing, initial findings suggest that the thin lithospheres on these worlds make them less ideal candidates when searching for Earth-like conditions elsewhere in the universe.^[4][9]

Future studies

Scientists are keen on studying eggshell planets further with the help of upcoming space telescopes.^[7] These future missions may provide more detailed observations, confirming the geological characteristics and potentially shedding light on the actual number of such planets in the universe. By studying these unique planetary bodies, scientists aim to discern the uniqueness or commonality of Earth-like conditions in the cosmos.^[2]

References

This page was last edited on 8 January 2024, at 00:10