First close-ups of Pluto thrill scientists

Mankind's first close-up look at Pluto did not disappoint on Wednesday: The pictures showed ice mountains on Pluto about as high as the Rockies and chasms on its largest moon, Charon, that appear six times deeper than the Grand Canyon.

Especially astonishing to scientists was the total absence of impact craters in a zoom-in shot of one otherwise rugged slice of Pluto. That suggests that Pluto is not the dead ice ball many people think, but is instead geologically active even now, its surface sculpted not by collisions with cosmic debris but by its internal heat, the scientific team reported.

Breathtaking in their clarity, the long-awaited images were unveiled in Laurel, Maryland, home to mission operations for NASA's New Horizons, the unmanned spacecraft that paid a history-making flyby visit to the dwarf planet on Tuesday after a journey of nearly 10 years and 4.8 billion kilometers.