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There must be a sweet spot size of planet that is less massive than ours, but that is still big enough to hold an atmosphere. edit: "That critical size, accord

There must be a sweet spot size of planet that is less massive than ours, but that is still big enough to hold an atmosphere. edit: "That critical size, according to Arnscheidt and the other authors of the study, is 2.7 percent the mass of Earth. They say that any smaller than that, and the planet simply won’t be able to hold onto its atmosphere and water long enough for life to appear." shorturl.at/bdgIK So, a mercury sized planet could hold an atmosphere in theory, and require around 1/3 the velocity to escape (vs. earth)

shagie 4y ago
The tangent to this is - the reason that Mars doesn't have much of an atmosphere isn't that its not gravitationally massive enough to hold on to it, but rather that its core cooled and lost its magnetic shielding. The lack of a magnetosphere then allowed the solar wind to strip its atmosphere. https://www.nasa.gov/press-release/nasas-maven-reveals-most-of-mars-atmosphere-was-lost-to-space https://www.nasa.gov/press-release/nasas-maven-reveals-most-...