After a 9-year hurtle through the heavens, the tiny New Horizons spacecraft messaged home shortly before 9 p.m. Tuesday, confirming its successful first flyby of Pluto.

NASA officials said they would release data and images from the flyby at 3 p.m. Wednesday.

Earlier Tuesday, New Horizons had greeted a cold, dark and distant Pluto 70 seconds ahead of schedule in a historic rendezvous with the demoted dwarf planet and its moons.

The NASA project was reported live by mission specialists at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, whose feed was beamed into the Rose Center for Earth and Space, part of the American Museum of Natural History in Manhattan.

Shortly before 8 a.m., as the Lilliputian probe grazed the ex-planet -- swooping within 7,800 miles of the surface -- the Rose Center's audience of 200-plus Pluto enthusiasts erupted into applause and cheers.

Seasoned scientists in New York and beyond could not contain their joy, some awestruck by a journey of 3.5 billion miles and a minuscule craft streaking through the cosmos at 31,000 miles per hour.

"I am almost beside myself. New doors are going to open up. Pluto is going to open doors for us," said Orkan Umurhan, a space scientist speaking via the Maryland hookup. "There is a tremendous amount of treasure that will come from this."

At the Rose Center, experts were equally enthralled.

"It's not every day that we get to see something for the first time, so this is a special day," said Neil deGrasse Tyson, director of the Hayden Planetarium and one of three experts at the Rose Center explaining the probe's close encounter with the planetary dwarf. The planetarium is a division of the museum.

The flyby differed from previous planetary visits. The Hopkins team opened the event to the public, allowing anyone who wanted to ask questions to do so. Science museums and observatories in the United States and abroad participated.

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A simulation of the spacecraft's close encounter played out on a theater-sized screen because it takes more than four hours for real-time data to reach Earth.

Carter Emmart, the museum's director of "astrovisualization" -- an expert in astronomy and computational data -- revealed exactly what's meant by far, far away. Clad in orange pants, his blond shoulder-length hair flowing, Emmart sped quickly back across the stage, putting Pluto's position in the heavens into perspective.

"That's Earth," he said, pointing to a barely visible speck. That's the sun," Emmart added, pointing to a somewhat larger and brighter speck. From Pluto's vantage point, the sun looks like any other star sprinkled throughout the galaxy.

Denton Ebel, chair and curator of planetary sciences at the museum described Pluto's galactic whereabouts another way, calling its home, the icy Kuiper belt where comets are born, "the deep freeze."

New Horizons is providing scientists with the data needed to map Pluto, a dinky sphere about the size of our moon. They've found it has an inexplicably bright area shaped like a heart and a variety of landscapes across its surface. Scientists also have confirmed methane and nitrogen ice at its poles.

Months before the flyby, New Horizons' lead investigator, Alan Stern, told Newsday the mission is a capstone event. He likened the probe's diminutive size to that of a baby grand piano. The spacecraft, he said, is expected to relay data for years to come as it journeys deeper into the universe.

"Pluto is the last picture show," Stern said of the Pluto flyby, the final stop in the solar system.

When the mission launched on Jan. 16, 2006, Pluto was a full-fledged planet. It was demoted nine months after the spacecraft's launch when the International Astronomical Union declared it a dwarf planet.

Tyson, however, doubts the New Horizons mission will produce data to reunite Pluto with its former solar system kin.

It was the Hayden Planetarium, he reminded his audience Tuesday, that was the first to reduce the number of planets from nine to eight, a move that occurred years before the union's vote. "Just to be clear, what we did here at this institution was to take Pluto and group it with other icy bodies," he said. "We were early out of the box in reclassifying Pluto."