Yesterday, a cosmic coincidence brought together two spacecraft. One, a veteran cosmic explorer, is hurtling ever outward toward the hinterlands of the solar system. The curtain is still waiting to rise on the other, a relative youngster that will soon be stepping into the spotlight.

On August 25, the Pluto-destined New Horizons spacecraft crossed Neptune’s orbit — 25 years to the day after its elder sibling, Voyager 2, swooped in for a close look at the big, blue ice giant and its curious, geyser-spewing moon.

That cosmic collusion of events helps mark the passing of a torch from one generation of space explorers to another, scientists said during a press conference commemorating the occasion.

A quarter-century ago, Voyager 2