> cool it down If you blocked all incoming sunlight, how long would it take for the surface to cool to human-tolerable temperatures? Or more extreme, how long

> cool it down If you blocked all incoming sunlight, how long would it take for the surface to cool to human-tolerable temperatures? Or more extreme, how long would it take to cool it down to the freezing point of CO2, then build some sort of maglev launch system and lob solid CO2 to... Mars maybe, that planet could use more atmosphere. And how much stuff would you need to launch to spin up Venus? Months long nights are not fun. Can you launch stuff to yield more spin, then have it sling around Earth or Mercury, and then have it hit Venus again, resulting in more spin up, i.e. getting twice the rotational acceleration from a launch?