While we do successfully track many asteroids (for at least part of their orbital periods), this does not mean that we track every asteroid, or even anywhere cl

While we do successfully track many asteroids (for at least part of their orbital periods), this does not mean that we track every asteroid, or even anywhere close to it. In fact, the vast majority of detected asteroid impacts were not predicted by tracking systems before they collided with our planet. This Wikipedia article [0] presents data measuring the (in)effectiveness of the current tracking systems ("the vast majority are still missed"), and describes flaws in the current approach, such as "blind spots" that exist for various reasons depending on tracking methodology, e.g.: > all ground-based telescopes have a large blind spot for any asteroids coming from the direction of the Sun.... [but even] space-based telescopes which can observe a much larger region of the sky around Earth.... still cannot point directly towards the Sun. From this perspective, not only do we fail to track every asteroid, but there are specific and predictable "blind spots" where we cannot track any objects. So if the argument is that aliens could park their ship where we can't see it, then it's not a sufficient counterargument to claim that we track a lot of asteroids, because (a) we still miss the vast majority of them, and (b) many of those we miss for predictable reasons that could be exploited by an adversary who wants to hide an object from our tracking systems. [0] https://en.wikipedia.org/wiki/Asteroid_impact_prediction#Effectiveness_of_the_current_system https://en.wikipedia.org/wiki/Asteroid_impact_prediction#Eff...