On Earth or an Earth-like planet, how long does it take for a molten surface to solidify into planetary crust, and how long does it take for that crust to develop into tectonic plates?
1$\begingroup$ Of the four rocky planets in our solar system, Earth is the only one that we know of with tectonic plates. Because Venus has permanently thick cloud cover its rock surface has never been seen on a global scale. A Russian probe was able to take a few photos of a localized region. It is believed that Venus does not have tectonic plates. $\endgroup$– FredFeb 27, 2020 at 11:10
1$\begingroup$ We currently do not know the answer to this question. The estimates regarding when plate tectonics started on Earth vary by over a billion years. Whether plate tectonics started (and later stopped) on Venus and Mars is subject to a huge amount of debate. While "we do not know" is may not be satisfying, "we do not know" is the bread and butter of the future generation of scientists. $\endgroup$– David HammenFeb 27, 2020 at 12:04