It might not be one thousand years. It will probably be more than 100 years. Of course, 100 vs 1000 is an unverifiable dichotomy. But hear me out. A sunshade

It might not be one thousand years. It will probably be more than 100 years. Of course, 100 vs 1000 is an unverifiable dichotomy. But hear me out. A sunshade big enough to make a difference for Venus would be of the order of 1 billion tons (why? I'm using the sunshield of James Webb, which is about 25 microns thick, and is made of a material called Kepton, which has a density similar to plastic; the rest is just multiplications). Moving a billion tons in space is not easy, thanks to the tyranny of the rocket equation. But if you are at the technological level of building a planet side sunshade, then you can probably build a parabolic mirror (made of the same mylar-like material like JWST's sunshield) []6781