CAPE CANAVERAL, Fla. — We’ve made it to Pluto by NASA’s calculations, the last stop on a planetary tour of the solar system a half-century in the making.

The moment of closest approach for the New Horizons spacecraft came at 7:49 a.m. EDT Tuesday, culminating a journey from planet Earth that spanned an incredible 3 billion miles and 9½ years.

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.

“This is truly a hallmark in human history,” said John Grunsfeld, NASA’s science mission chief.

“It’s a moment of celebration,” added principal scientist Alan Stern from Johns Hopkins University’s Applied Physics Laboratory, the spacecraft’s developer and manager. “We’ve just done the anchor leg, we have completed the initial reconnaissance of the solar system, an endeavor started under President Kennedy more than 50 years ago.”

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, on Jan. 19, 2006, but was demoted seven months later to dwarf status. Scientists in charge of the $720 million mission, as well as NASA brass, hope the new observations will restore Pluto’s honor.

“It’s a huge morning, a huge day not just for NASA but for the United States,” NASA Administrator Charles Bolden said from NASA headquarters in Washington.