As we get word on more information about New Horizons, we'll place timestamped updates on top of this post.

Overnight update: The tension was thick tonight as the whole world waited for NASA's New Horizons spacecraft to phone home. At 8:52:37 pm EDT mission control received a signal from NASA's Deep Space Network (DSN) confirming the spacecraft was healthy and on its way out to the outer reaches of the Solar System. When the signal came in, the crowd at Johns Hopkins University's Applied Physics Lab broke out in thunderous applause.

The signal was part of a a 15-minute communications pass and contained only engineering information—no science data will come in until tomorrow. John Grunsfeld, associate administrator for NASA's science mission directorate, equated tonight's phone home with the Curiosity Rover's landing back in 2012 and said "The best is yet to come. Tomorrow we can expect the science team to dazzle us. We haven't seen anything yet."

Charlie Bolden, NASA's administrator, said in a post-event press conference, "This is a historic

win for science and exploration. We are inspiring the next generation of explorers and have truly raised the bar of human potential."

Stay tuned as we are promised some very exciting images and data tomorrow.

8:56 PM Eastern Update: All hardware is healthy, and it looks like the expected amount of data was recorded during the flyby.

8:55 PM Eastern Update: "We are in lock with telemetry on the spacecraft." The room erupts in cheers.

LAUREL, Md.—Today, NASA made history by becoming the only space agency to explore all of the bodies in the classic Solar System. Decades in the making, the NASA-led New Horizons mission completed its historic flyby of Pluto and its five moons at 7:49am EDT. After traveling 9.5 years and over three billion miles, New Horizons was busy snapping pictures and collecting as much data as it could while it soared between the dwarf planet and its largest moon, Charon.

The spacecraft whizzed by 72 seconds ahead of schedule and at a distance of only 12,500 kilometers from the dwarf planet’s surface—70 kilometers closer than first predicted.

The atmosphere has been electric all day here at Johns Hopkins University's Applied Physics Lab. Shortly before the scheduled flyby time, there was a New Year’s Eve style countdown as the song “The Final Countdown” played in the background. Instead of a ball dropping, TV screens featured a digital countdown and when the timer hit zero, the room erupted in loud cheering, applause, and flag waving.

The real cheering, however, will come later this evening when the probe “phones home” to let everyone here on Earth know it survived the flyby. The spacecraft’s trajectory had it flying through the system—meaning between Pluto and its largest moon Charon. Using spacecraft data along with data from observatories such as the Hubble Space Telescope, mission scientists double and triple checked for potential debris that could damage the spacecraft prior to flyby. Despite the odds of an incident being very low, the mission team won’t be able to relax until after they hear from the little probe.

The historic flyby is happening 50 years to the day after NASA’s first successful Mars flyby, performed by the Mariner 4 spacecraft. On the momentous occasion, NASA Administrator Charles Bolden said “The exploration of Pluto and its moons by New Horizons represents the capstone event to 50 years of planetary exploration by NASA and the United States. We have achieved a historic first as the United States is the first nation to reach Pluto and with this mission has completed the initial survey of our Solar System, a remarkable accomplishment.”

Around 11:15 pm EDT on July 13, prior to closest approach, the New Horizons spacecraft went silent as it busied itself collecting data on the icy world and its family of moons. Before doing so, it snapped and sent back the best view we have so far of Pluto. One last picture as a safety precaution in case something went amiss during the flyby—a practice NASA has been doing since the Apollo days. The image was released earlier this morning and will be the last image we see until Wednesday.

Prior to closest approach, New Horizons’ Ralph and Alice instruments, a pair of spectrometers, also imaged both Pluto and Charon. NASA released false color images to show the differences in surface material and features on each. The color data helps the science team understand the molecular make-up of surface ices as well as determine the age of craters and other geologic features.

Pluto has been described as the other red planet; meaning it’s similar in color to Mars, although it gets that color via a very different process. This new data shows that the reddish coloring on Charon’s northern polar cap may be attributed to the presence of hydrocarbons known as tholins—just like Pluto.

Thanks to New Horizons, scientists now have an accurate measurement of the dwarf planet’s size. Pluto is 2,370 kilometers in diameter, larger than previously predicted. We can now definitively say that Pluto is the largest known body beyond Neptune.

Since its discovery in 1930, Pluto’s size has been a subject of debate. Mission scientist Bill McKinnon of Washington University in St. Louis said, “We are excited to finally lay this question to rest.” With the new size data, scientists have determined that Pluto is less dense than previously predicted and the fraction of interior ice is slightly higher. Recent New Horizons data confirms that Pluto’s largest moon, Charon, is 1208 kilometers in diameter—just as predicted from ground-based measurements.

“New Horizons is the gift that keeps on giving,” said principal investigator Alan Stern. The spacecraft has already provided unprecedented views of the icy world, and will continue to send back data over the next 16 months. Stern went on to say, “Our knowledge of the Pluto system can fill up a couple of sheets of notebook paper currently, but by the time we go through all the data, we can write the textbook on Pluto.”

Pluto was first discovered in 1930 by Clyde Tombaugh of Lowell Observatory. He was hired by Percival Lowell to help search for the mysterious planet X Lowell thought lurked in the outer Solar System. "Pluto was discovered just 85 years ago by a farmer's son from Kansas, inspired by a visionary from Boston, using a telescope in Flagstaff, Arizona,” said John Grunsfeld, associate administrator for NASA's Science Mission Directorate in Washington.

Tombaugh, only 24 when he discovered Pluto, spent thousands of hours in search of the tiny planet. The discovery started a revolution in how we view the Solar System, and scientists now have reason to think there are thousands of icy objects out beyond Neptune, orbiting in the region of the Solar System known as the Kuiper Belt.

Tombaugh passed away in 1997 at the age of 90, before the launch of New Horizons. As a tribute to him, the spacecraft is carrying a small container holding one ounce of Tombaugh’s ashes. His children were present today for the flyby and his daughter Annette Tombaugh said, “When my dad first looked at Pluto, it was just a speck of light. To actually see the planet that he discovered and find out more about its atmosphere, moons, and surface, my dad would have been astounded.”

There are parallels with the twin Voyager space probes, which gave us our first up close views of the planets and moons in the outer Solar System just as New Horizons is giving us the first up close views of Pluto and its moons. In fact, NASA briefly considered sending the Voyager 1 probe to flyby Pluto but that trajectory would mean the probe would miss important targets like Saturn’s moon Titan, which were crucial to its mission.

After Voyager 2 sent back the first look at Neptune and its largest moon Triton, a group of scientists including Alan Stern petitioned to NASA for a mission to Pluto. Their dream came true many years later with New Horizons.