After decades of failures and misunderstandings, scientists have solved a cosmic riddle — what happens to the tons of dust particles that hit the Earth every day but seldom if ever get discovered in the places that humans know best, like buildings and parking lots, sidewalks and park benches.

The answer? Nothing. Look harder. The tiny flecks are everywhere.

An international team found that rooftops and other cityscapes readily collect the extraterrestrial dust in ways that can ease its identification, contrary to science authorities who long pooh-poohed the idea as little more than an urban myth kept alive by amateur astronomers.

Remarkably, the leader of the discovery team — and co-author of a recent paper in Geology, a monthly journal of the Geological Society of America — turns out to be a gifted amateur who devoted himself to disproving the skeptics.

A noted jazz musician in Norway, he rearranged his life to include eight long years of extraterrestrial sleuthing. His hunt has now produced a significant discovery, a colorful book for lay readers and what scientists call a portrait gallery of alien visitors.