On Tuesday, July 14, 2015, at 11:49 UTC (7:49 a.m. EDT), the New Horizons spacecraft reached its closest point to Pluto, passing 12,500 kilometers (7,750 miles) above the surface of the dwarf planet while traveling at approximately 14 kilometers per second (31,000 miles per hour).
During its flyby, New Horizons used its suite of instruments to examine the geology and map the surface compositions and temperatures of Pluto and that of its largest moon, Charon; study Pluto's four smaller moons and search for any heretofore undiscovered satellites; measure Pluto’s atmosphere and assess whether Charon possesses one; and look for rings around Pluto. The craft sent a preprogrammed message at 9:02 p.m. EDT on July 14 confirming that it had remained operational, and its equipment will continue to report findings back to Earth over the next 16 months.
Located in the Kuiper Belt past the rocky planets of the inner solar system and the gas giants of the central solar system, Pluto is, on average, 5.9 billion kilometers (3.7 billion miles) away from the sun and takes 248 Earth years to make a single orbit of the sun. Five-and-a-half times smaller than Earth, Pluto has a surface comprised of a mixture of ice and rocky material and a temperature of -238 to -218 degrees Celsius (-396 to -360 degrees Fahrenheit).
Sent into space nearly a decade ago, on January 19, 2006, New Horizons, similar in size to a baby grand piano, is the fastest spacecraft ever launched. Over the course of its more than 3-billion-mile journey, New Horizons did a flyby of Jupiter in order to use the giant planet's gravity to speed the craft toward Pluto three years faster than it would have been able to reach it otherwise. At the same time, New Horizons gathered 700 observations about Jupiter and its moons, including close-up images of the planet's famous Red Spot.
After it departs Pluto's vicinity, New Horizons will continue into the Kuiper Belt, the disk of thousands of icy objects (known as Kuiper Belt objects) in our solar system outside Neptune's orbit, to further study this unexplored third zone of our solar system, home to dwarf planets and most short-period comets.
Do you want to hear the latest news from the flyby? NASA will hold a media briefing on NASA's tv stream at 1 p.m. EDT Friday, July 17, to reveal new images of Pluto and discuss new science findings from Tuesday’s historic flyby. Questions from the public are welcome on Twitter using the hashtag #askNASA.
Want to get more of Pluto's story? You can use Science NetLinks' resources to learn more about Pluto and why it's no longer considered the solar system's ninth planet with Is Pluto a Planet? Watch video interviews with Alan Stern, New Horizons principal investigator, about the upcoming Pluto encounter and what is next for his NASA spacecraft, and Michael Brown, astronomer, about the solar system's bodies and his role in the demotion of Pluto from planet to dwarf planet. AAAS has created a landing page with additional Pluto resources that includes a quiz, an editorial, and profiles.
If Pluto gets you excited about space exploration, you can further explore the solar system and its planets, compare their mass and size, play a game that lets you pilot a spaceship, and learn more about how to make your own observations of the night sky. You might also find MESSENGER, the recently completed Mercury mission, of interest.