Myth Debunked: How likely are doomsday comet scenarios?

While most near-Earth objects of significant size are largely accounted for and monitored, long-period comets like C/2023 A3 Tsuchinshan-ATLAS or C/2020 NEOWISE are always discovered mere months before they make their closest passage to Earth. This is to be expected, given the unpredictable nature  and the relatively small size of these cosmic bodies, coupled with...