Climate collapse, Fermi paradox
How fucked up would it be to find ruins of a highly technological civilization on Venus?
Venus is totally in the habitable zone (although it has very long days) and the only reason it's so hot is because its dense CO2-rich atmosphere. What if once it had sentient life and they started a runaway global warming...?
I wonder if it's possible that an artificial satellite orbiting Venus would have remained invisible to this day. If it has a small enough radar cross-section and stable orbit...
I wish I would know more astronomy.
@Feufochmar But how much carbon is still in hydrocarbon and coal form on our planet? What if we burn everything? (if the atmosphere gets depleted, we can liberate oxygen from minerals, it's just a matter of energy)