LOS ANGELES (CBSLA.com/AP) — 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 around 7:49 a.m. EDT Tuesday, culminating an epic journey from planet Earth that spanned an incredible 3 billion miles and 9 1/2 years.

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

Based on everything NASA knows, New Horizons was pretty much straight on course for the historic encounter, sweeping within 7,700 miles of Pluto at 31,000 mph. It actually happened 72 seconds earlier and about 40 miles closer than anticipated.

But official confirmation of the flyby wasn’t due 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.

Ed Krupp, who runs the Griffith Observatory, told KNX 1070 NEWSRADIO his facility will be a great place to go for anyone who wants to follow the mission.

“We’ll be having live NASA TV coverage available on all the screens of the Observatory, so anyone who visits us will be able to see what’s going on with NASA at that time,” said Krupp.

Starting at 1 p.m., the Observatory will be giving 20-minute presentations on Pluto every hour.

In a cosmic coincidence, the encounter occurred on the 50th anniversary of Mariner 4’s flyby of Mars that yielded the first close-up pictures of the red planet.

“I think it’s fitting that on the 50th anniversary we complete the initial reconnaissance of the planets with the exploration of Pluto,” said principal scientist Alan Stern.

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.

NASA marked the moment live on TV, broadcasting from flight operations at Johns Hopkins University’s Applied Physics Laboratory, the spacecraft’s developer and manager.

“Getting to be a part of the excitement and of this moment in history is really special,” JPL’s Amanda Allen said.

Inside “countdown central” in Laurel, Maryland, hundreds jammed together to share in the remaining final minutes, including the two children of the late American astronomer who discovered Pluto in 1930, Clyde Tombaugh. The actual flight control room was empty save for a worker sweeping up; the spacecraft was pre-programmed for the flyby and there was nothing anyone could do at this point but join in the celebration.

The crowd waved U.S. flags and counted down from nine seconds, screaming, cheering and applauding. Chants of “USA!” broke out.

“We learn more about how the solar system formed and evolved, and that tells us more about how our own planet formed and evolved,” JPL’s Marc Rayman said. “We did it. Humankind has another exciting accomplishment in the exploration of the cosmos.”

Among the dwarf planet’s features photographed by New Horizons is a heart-shaped region in Pluto’s southern hemisphere. NASA astronaut Scott Kelly, currently orbiting Earth on the International Space Station, tweeted a picture of a similar feature on our own planet.

Dr. Stephen Hawking shared a congratulations over YouTube on Tuesday, following the flyby.

“I would like to congratulate the New Horizons team,” Dr. Hawking shared.

Griffith Observatory is set to hold a free event from 5 p.m. to 7 p.m. to live stream NASA’s coverage of the flyby. The observatory is then set to share Pluto over their main telescope, starting at 9:30 p.m.

At a news conference afterward, Grunsfeld, Stern and mission operations manager Alice Bowman unveiled a picture of Pluto taken just Monday. The icy, impacted world — brassy-colored with bright, white spots at points northward and darker areas around the equator — drew admiration from the crowd.

Even better pictures will start “raining” down to the ground beginning Wednesday, Stern said, “a data waterfall.” But he cautioned everyone to “stay tuned” until New Horizons phones home Tuesday night. Only then will anyone know whether the spacecraft survived its passage through the Pluto system, five moons included.

“Of course, if we get that signal, we’ll all breathe a sigh of relief, knowing it’s made it through, and I assume there will be a huge cheer,” Dr. Krupp said.

“Hopefully it did, and we’re counting on that,” Stern told journalists. “But there’s a little bit of drama because this is true exploration. New Horizons is flying into the unknown.”

It takes 4 1/2 hours for signals to travel one-way between New Horizons and flight controllers, the speed of light. The last time controllers heard from the spacecraft was Monday night, according to plan, and everything looked good.

New Horizons already has beamed back the best-ever images of Pluto and big moon Charon. Pluto also has four little moons, all of which were expected to come under New Horizons’ scrutiny.

Bowman said she has to pinch herself as she reflects on all the mission’s accomplishments.

“To see Pluto be revealed just before our eyes, it’s just fantastic,” she said. She considers New Horizons like her own child and is simultaneously “nervous and proud” as she waits to hear back from it.

Pictures from the actual flyby, won’t be transmitted until well afterward so the seven science instruments can take full advantage of the encounter. In fact, it will take more than a year to get back all the data — 16 full months, or until October or November 2016.

On the eve of the flyby, NASA announced that Pluto is actually bigger than anyone imagined, thanks to measurements made by the spacecraft, a baby grand piano-size affair. It’s about 50 miles bigger, for a grand total of 1,473 miles in diameter.

Pluto is now confirmed to be 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.

If a mission extension is granted, New Horizons will seek out another Kuiper Belt object before heading out of the solar system — for good.

Shortly before 6 p.m., it was reported that the New Horizons spacecraft was indeed healthy and intact, as she continues her journey outward into the unknown, beyond Pluto.

Charlie Bolden spoke at roughtly 6:30 p.m., shortly after receiving the expected signal from New Horizons, stating, “We have now visited every planet in our solar system.”

“You have made Pluto almost human,” Bolden added, speaking directly to the New Horizons team.

Based on the interest and enthusiasm surrounding the achievement, he’s right.

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