The Solar System races around the galactic circuit like a runner on a track, and occasionally throws rocks: comets, asteroids, and even crumbs – meteorites. Such a thrown rock doesn't disappear forever. Computer simulations show: one in a hundred trillion pieces returns each year, catching up to the runner with almost no lag.

These 'returnees' barely outpace the Sun — their speed is like a pedestrian's — and arrive from two narrow sectors. True guests from other stars rush faster and more uniformly. Amazingly, a rock ejected in the dinosaur era could return today — for 66 million years it barely fell behind, as if tethered by Newtonian gravity. Returnees are witnesses of the young Sun, galactic evolution, and the lives of other stars.