When the solar system passes through the disk of dark matter, that could exert enough of a gravitational influence to disrupt the orbits of comets on the solar system’s edge. Such comets could become more likely to head into the inner solar system, periodically raising the chances of collision with Earth.
Some astronomers see a rising and falling pattern in the rate of cratering on Earth, tracing a cycle that lasts 25 million to 35 million years. Could extinction-level “storms” of comets account for those periodic rises in cratering? “We conclude that if a dark disk exists, it could play a significant role in explaining the observed pattern of craters, and perhaps even mass extinctions,” Randall and Reece say in their paper.
The research paper has been accepted for publication in Physical Review Letters. A comment on the paper notes that it contains “4 figures, no dinosaurs.”