4 ms·

But you only need one. Maybe two for good measure

• kadoban 2y ago
  Same with a nuke or an engineered pathogen. Throwing rocks from the Moon is less practical though, people would see you setting up the universe's biggest launch pad or railgun for years. It would be the least stealthy, most telegraphed apocalypse possible.
  • withinboredom 2y ago
    It only takes a 50-meter (radius) rock to destroy a city, a 240-meter rock to destroy an entire region, and a 4 km rock to destroy the planet. So, I guess it depends on what you want to accomplish, whether they see it coming or not.
    • kadoban 2y ago
      "Only". Those are huge! Especially when you consider the city you have to build around them to launch the damn things.
      • withinboredom 2y ago
        The required delta-v isn't all that much from the moon, and it's more about the mass and speed than the actual shape of the rock.