NASA's New Horizons made the closest approach to dwarf planet Pluto on Tuesday evening, more than nine years after it blasted off from earth.
The moment of closest approach for the New Horizons spacecraft came at 7:49am EDT on Tuesday culminating an unprecedented journey spanning 3 billion miles.
Based on everything NASA knows, New Horizons was straight on course for the historic encounter, sweeping within 7,800 miles of Pluto at 31,000 mph. But official confirmation won't come until Tuesday night, 13 nerve-racking hours later.
That's because NASA wants New Horizons taking pictures of Pluto, its jumbo moon Charon and its four little moons during this critical time, not gabbing to Earth.
NASA marked the moment live on TV, broadcasting from flight operations in Maryland.
The United States is now the only nation to visit every single planet in the solar system. Pluto was No. 9 in the lineup when New Horizons departed Cape Canaveral, Florida, in 2006 to shed light on the mysterious icy world, but was demoted seven months later to dwarf status.
It's the final destination on NASA's planetary tour of the solar system, which began more than a half-century ago. Pluto was still a full-fledged planet when New Horizons rocketed away in 2006, only to become demoted to dwarf status later that year.
The New Horizons team gathered at Johns Hopkins University's Applied Physics Laboratory in Laurel, Maryland, won't know for many hours if everything went well.
The spacecraft will be too busy taking photographs and collecting information to "phone home." A confirmation signal is expected at around 0100 GMT on Wednesday.
New Horizons has already beamed back the best-ever images of Pluto and big moon Charon. Pluto also has four little moons.
The pictures already gathered by New Horizons are "mind-boggling to put it mildly," Bolden said. Pluto has proven to be bigger and redder than anyone imagined, he said, and the data may put the faraway world back in the primary planet lineup.
Principal scientist Alan Stern told reporters Monday that "The Pluto system is enchanting in its strangeness, its alien beauty."
Discovered in 1930, Pluto is the largest object in the so-called Kuiper Belt, considered the third zone of the solar system after the inner rocky planets and outer gaseous ones. This unknown territory is a shooting gallery of comets and other small bodies.
An extension of the $720 million mission, not yet approved, could have New Horizons flying past another much smaller Kuiper Belt object, before departing the solar system.