On the eve of NASA's historic flyby of Pluto, scientists and tourists at the Lowell Observatory in Flagstaff, Arizona are excited about the images and discoveries the New Horizons' spacecraft will beam back to Earth. After nine-and-half years of traveling 5.3 billion km (3.3 billion miles), National Aeronautics and Space Administration (NASA)'s spacecraft New Horizons will get within 12,500 km (7,800 miles) of Pluto on Tuesday evening. Image copyright NASA Image caption How Pluto and its biggest moon, Charon, compare in size to the Earth 
 
 The BBC will be screening a special Sky At Night programme called Pluto Revealed on Monday 20 July, which will recap all the big moments from the New Horizons flyby. They’ll also be looking for clues to how the Pluto system formed and evolved—and many of those clues might lie in the features of the four small moons Nix, Hydra, Kerberos, and Styx . NASA's New Horizons mission to the Pluto-Charon system has yet to mark its finest hours – a historic flyby that makes its closest approach to the binary planet and its moons Tuesday morning. 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.
– This is one of the biggest days in the exploration of our solar system since Voyager 2 approached Neptune in 1989—and there may not be a day like it again. According to NASA's calculations, its New Horizons spacecraft flew by Pluto at 31,000mph at 7:49am EDT today; confirmation of that will come tonight, some 13 hours later, reports the AP. The confirmation will mark the completion of NASA's tour of the "classical nine" planets, reports the AP, which notes that Pluto was considered a full-fledged planet instead of a dwarf one when the probe began its journey in 2006. Some things to know about the historic flyby, which comes 50 years to the day after the first successful flyby of Mars: New Horizons will have to capture a vast amount of data in a short time. The probe will be pushed to its limits as it pivots to capture photos and information on Pluto and its moons Charon, Styx, Nix, Kerberos, and Hydra during the flyby. "I can't wait to get into the data and really start making sense of it. Right now, we're just standing under the waterfall and enjoying it," principal New Horizons scientist Alan Stern tells the BBC. We don't know whether it was a success. The probe is far too busy to "phone home," the AP notes, but it's expected to send a confirmation signal at around 9pm tonight. The eagerly awaited first photos from the flyby should be released tomorrow night, the Guardian reports, though it will take 16 months to send all the data from the flyby back to Earth. We've already learned a lot of new things about Pluto. "The science we've already made is mouth-watering," says Stern. "The Pluto system is enchanting in its strangeness and its alien beauty." Among NASA's findings in recent days: Pluto's North Pole has an icy cap and the planet's diameter is 1,597 miles across, not 1,471 miles as previously thought. The finding suggests the planet contains a lot more ice and a lot less rock than thought, the Christian Science Monitor reports. There are still a lot of mysteries to be solved. Scientists hope the first close-up look at Pluto's surface will explain features like heart- and doughnut-shaped features recently spotted for the first time. LiveScience notes that new information from Pluto could help explain how our own planet formed and how life began. "There's a feeling among scientists that Pluto probably will tell us what the early solar system looked like and it's now locked in deep freeze and maybe it will tell us what we once were, a long time ago," the director of the Deep Space Communication Complex tells Reuters. The Australian facility will be first to receive new information from the spacecraft. New Horizons isn't done. New Horizons will keep traveling into the Kuiper Belt debris field and beyond after it passes Pluto, National Geographic notes, and it may have more research to do if NASA approves funding. (The astronomer who first spotted Pluto in 1930 is the spacecraft's only passenger.)