Snow Globe

Instead of floating inside an orb, these flakes, some of the solar system’s newest ornaments, dance around it. The ­dusting comprises active ­satellites and tens of thousands of space scraps—including wrenches left behind after extra­terrestrial home-repair projects, bits of long-abandoned satellites, and actual trash bags stuffed with the detritus of manned space flight. The number of pieces of junk in this orbiting garbage dump, which circles Earth at speeds up to 7800 meters per second, is ­multiplying; when the particles collide, they break into smaller pieces that some believe could eventually make it too risky to put ­satellites into orbit or even to explore outer space.