The minimum mass for an exoplanet or moon to sustain plate tectonics is suggested to be around 0.2 Earth masses. However, the presence of water is crucial for lubricating the tectonic plates. Additional factors influencing plate tectonics include the body's rotation, tidal effects from nearby celestial bodies, and the internal heat of the planet or moon. Even smaller planets or moons can potentially maintain sufficient internal heat for tectonic activity. Overall, multiple conditions must be met for plate tectonics to occur on exoplanets or moons.
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KTevolved
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What would be the minimum mass for an exoplanet or moon to sustain plate tectonics? I would think its 0.2 Earth masses.
Yes 0.2 Earth masses sounds right for the very minimal mass for sustained plate tetonics but you would need water to lubricate the plates. There are other factors that come into play also like rotation, tidal effects of a moon, how much heat the interior has. Even a small planet or moon could have enough heat in the interior.
Partial solar eclipse from Twizel, South Isl., New Zealand ...
almost missed it due to cloud, didnt see max at 0710 NZST as it went back into cloud.
20250922, 0701NZST
Canon 6D II 70-200mm @200mm,
F4, 100th sec, 1600ISO
Makeshift solar filter made out of solar eclipse sunglasses
Is a homemade radio telescope realistic?
There seems to be a confluence of multiple technologies that makes the situation better than when I was a wee lad: software-defined radio (SDR), the easy availability of satellite dishes, surveillance drives, and fast CPUs.
Let's take a step back - it is trivial to see the sun in radio. An old analog TV, a set of "rabbit ears" antenna, and you're good to go. Point the antenna at the sun (i.e. the ears are perpendicular to it) and there is...
3I/ATLAS, also known as C/2025 N1 (ATLAS) and formerly designated as A11pl3Z, is an iinterstellar comet. It was discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) station at Río Hurtado, Chile on 1 July 2025.
Note: it was mentioned (as A11pl3Z) by DaveE in a new member's introductory thread.
https://www.physicsforums.com/threads/brian-cox-lead-me-here.1081670/post-7274146
https://earthsky.org/space/new-interstellar-object-candidate-heading-toward-the-sun-a11pl3z/
One...