Neil deGrasse Tyson and friends gush over today's Pluto flyby

At around 7:50AM Eastern this morning, NASA's New Horizons probe reached its closest point to Pluto, around 7,750 miles away, where it unleashed its full array of equipment to give us our best look yet at the dwarf planet. It's the culmination of a nine-year journey across more than 3 billion miles -- and the scary thing is we won't even know until tonight if it succeeded. To celebrate the occasion, we joined Neil deGrasse Tyson, his colleagues and a theater full of science geeks at the American Natural History Museum to explore what the New Horizons mission really means. You can check out the full session, as well as some highlights from the event, below.

Tyson, along with Denton Ebel, chair and curator of the AMNH Earth and Planetary Sciences department, and Carter Emmart, the museum's director of astrovisualization, kicked things off by going over the basics of the mission. New Horizons launched in 2006 as the first NASA mission dedicated to exploring Pluto, which followed years of failed lobbying efforts by scientists and the cancellation of another mission. Its main goal is to map the geology and chemical composition of Pluto and its largest moon Charon, as well as get more information about Pluto's atmosphere. But NASA also has a slew of other goals in mind: It'll map the surfaces of Pluto and Charon with high-resolution pictures; search for additional moons outside of the five we already know of; search for a ring system around Pluto; and perhaps most intriguingly, it will try to determine if Pluto and Charon share an atmosphere.

"To see a distant object for the first time is among the oldest emotions humans have ever had. ... Ever since we've left the cave." Tyson said, following New Horizon's close encounter with Pluto (at 54:27 in the video above). As momentous as the occasion was (naturally, the audience erupted in cheers), it also involved plenty of imagination from everyone involved. We were celebrating based on estimated timing from NASA and a virtual look at New Horizons and Pluto via OpenSpace, not a live feed of information. The spacecraft can't send and collect data at the same time, so we'll have to wait for confirmation tonight that it's still working, and we won't see any actual data until tomorrow.

"We've reached another zone of our reality, of our universe," said astrobiologist David Grinspoon. He noted that New Horizons is the first "post-human" planetary encounter -- it used to be that only the privileged few in mission control could celebrate; now anyone with internet access can virtually follow along.

Frances Bagenal, New Horizon's co-investigator, said she hopes the mission will inspire us "to go back out and explore," adding, "just because we've checked off Pluto doesn't mean we should stop." Tyson echoed that sentiment, saying he'd rather think of New Horizons as the last reconnaissance of the solar system's nine planets, and the first exploration of the Kuiper belt, the far-off territory that includes Pluto and Eris (the dwarf planet that convinced scientists to demote Pluto's planetary status).

A few takeaways from the event:

  • New Horizons is the fastest spacecraft ever launched by NASA, traveling at around 37,000 miles per hour.

  • It's not fast enough to surpass Voyager 1, though, which has been hurtling through space since 1977 and has picked up quite a bit of velocity along the way.

  • Pluto's distance from the sun isn't the only thing that makes it so cold: Its high albedo (sunlight reflectivity) means it sends back most of the light that actually reaches it.

  • Tyson asked why NASA chose to make New Horizons a flyby mission, rather than one that will hang around Pluto for extended study. Bagenal said a big reason was fuel -- you've got to take more if you want to stay near a planet. It's much easier to fly past it and get as much data as you can. And of course, you have the added benefit of traveling farther out.

NASA will give us an update on New Horizons' health in a live stream tonight at 8:30PM Eastern. But you'll have to wait until 3PM tomorrow for the first bounty of images to hit.