4 ms·
That really makes a lot of sense. Because planets smaller than Earth cool a lot faster, so they lose their molten core and plate tectonics (which keeps land ma
by derekp7 7y ago
That really makes a lot of sense. Because planets smaller than Earth cool a lot faster, so they lose their molten core and plate tectonics (which keeps land mass rising and out of the water), and also a magnetic shield that keeps the atmosphere from stripping away (like Mars).
- JohnJamesRambo 7y agoI'm going to be hopeful and optimistic and point out that the large planets in our solar system aren't rocky and suitable for life as we know it anyway. Earth is the biggest one and the rest are gas planets. Maybe planets that harbor life (rocky, liquid water, goldilocks zone closer to the sun) usually have low enough gravity for aliens to escape it. This diagram has some exoplanets on it for size comparison- https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#/media/File:Diagram_of_different_habitable_zone_regions_by_Chester_Harman.jpg https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#/...
- api 7y agoEarth might be right at this threshold of small enough for space flight to be practical (still hard, but practical) but big enough to hang onto water and atmosphere.