Every fourty-two years, the Nearing-Dai Song Comet streaks into the inner solar system. It tends to bring with it a collection of rocks from the Outer System, and to leave behind it a trail of rocks, ice balls, gas. Some is captured by the planet known to the locals as Earth.
The N-DS is the center of a mobile sub-universe which is centered on its parts. This has the effect called by the students of weird phenomenon, the 'Weirdness Mountain' after the shape on a graph paper of 'weird incidents' on Earth. As the comet comes inward, it pushes bits of ice and stuff before it, and each of those bits has a sub-universe around it that is unstable because its so small.
Some bits are large enough to cause effects even from orbit, so you have five minute chunks of time in every ninety minutes where locals on the planetary surface can do strange things.
Other chunks are sturdy or large enough to survive crashing to Earth. Being turned into vapor tends to destroy the effect. But if a large meteor crashes down near a village, the whole village is likely to start seeing 'Weird Incidents' as people learn to manipulate the new potential for abilities.
Then the comet nears the Earth, and weirdness is much more common for a month, but its still denied. Later, the comet leaves and you're left with the bits that crashed either before or after.
However, the sub-universe tends to decay after a span from a week to a year to normal reality.
Bits of the comet have different chunks of high bias reality attached to them. So in one town you might see faith healers, and in another town an outbreak of telepathy.
There are legends of intermittent powers and madness, and some organizations have some clue as to what's going on.
Some astronomers claim to be able to see structures on the N-DS but this is considered fringe science. In actuality, there are the ruins of an alien exploration ship and base on the comet. Its the only place in the solar system where the ship's hyperdrive and AI can work. The aliens dropped into the system from hyperdrive, and could not leave. They found the comet, and settled there, but by then the hyperdrive had been badly damaged due to klutzy bias impaired 'repairs'. The aliens may have gone into hypersleep hoping that someone in the future could rescue them, and help them jump from the comet back to 'normal reality' outside the solar system.
