Editor’s Note: Scroll down for earlier updates.
Three billion miles from Earth, our solar system’s loneliest, coldest planet awaits a long-anticipated visitor.
At approximately 7:49 a.m. EDT on July 14, NASA’s New Horizons spacecraft is slated to hurtle past Pluto, the dwarf planet formerly known as a planet.
As it zips by, New Horizons will take pictures of Pluto’s landscape and analyze its exotic atmosphere before being catapulted into the Kuiper Belt, a veritable graveyard of our solar system’s earliest occupants. Back at the Johns Hopkins Applied Physics Laboratory, scientists and engineers are anxiously counting down the days, hours, and minutes until the flyby occurs. The event will not only complete humankind’s first era of planetary exploration—it will also mark the end of a long journey for the experts who’ve been holding their breath since the spacecraft launched on January 19, 2006.
Pluto has a number of odd features that the New Horizons team is looking forward to understanding better. Its four small moons have rocky, turbulent orbits—and one of them, Kerberos, is darker than the rest. Charon, the largest moon, has an intriguing dark patch. Pluto itself has an unexpected bright spot near its north pole that could be a polar ice cap; even very pixelated images reveal that Pluto’s light areas could house miles and miles of ice. In addition to all that, Pluto might have an equatorial ridge, a landform that exists in only one other place in the solar system: Saturn’s moon Iapetus.
Over the next week, we’ll be providing live updates on the mission—both from our offices in Boston and while I’m on-scene at New Horizons Mission Control next week. Keep returning to this page for ongoing exclusive coverage, and follow us on Facebook and Twitter.
Update, 7/17 at 1:00 p.m.: NASA released new images of Pluto, depicting an icy plain dubbed “Sputnik Planum” that’s broken up into polygonally-shaped segments bordered by troughs of darker, hilly material. The New Horizons team says this landscape—a major source of carbon monoxide—is “hard to explain.” Dark smudges are also sprinkled throughout the photograph, which could be plume deposits—or the result of winds blowing across the ice. They also discovered that Pluto has a “tail” of ionized nitrogen from that’s being carried away by solar wind at a rate of 500 tons per hour. Finally, the scientists revealed a photo of Pluto’s moon Nix and confirmed that the spacecraft is now 2 million miles away from the far side of Pluto.
Update, 7/15 at 3:00 p.m.: Distant Pluto shows signs of youth, even after 4.5 billion years.
Update, 7/15 at 1:28 p.m.: NASA says that today’s images (to come at 3 p.m. EDT) will be a sight better than the first we saw of Mars 50 years ago today.
Update, 7/14 at 8:53 p.m.: “We have a healthy spacecraft!” —Alice Bowman, Mission Operations Manager. The fly-by was successful.
Update, 7/14 at 2:17 p.m.: Pluto is already revealing its true colors. Scientists react and explain what they’ll be looking for.
Update, 7/14 at 12 p.m.: Check out this Reddit AMA happening right now with members of the NASA New Horizons team.
Update, 7/14 at 8 a.m.: NASA released its latest image of Pluto, the last before closest approach, on its Instagram account. Project Investigator Alan Stern says that it looks like snow and tectonics are possible, and the team is going to be assessing the planet’s topography and atmosphere to better understand what’s actually going on in this photo. In addition, they want to find out why Charon looks so old and “battered” compared to Pluto—is Pluto’s atmosphere simply obscuring its blemishes?
Update, 7/13: In this image, Pluto’s bright “heart” is rotating into view from a distance of 1.6 million miles. The dwarf planet’s four dark spots, or “brass knuckles” (as they’re being nicknamed), are rotating out of view for the last time. These dark spots are each about 300 miles wide—the size of Missouri. The team also pinpointed Pluto’s and Charon’s sizes today—Pluto is 18.5% the size of Earth, and Charon is 9.5%.
Update, 7/12 at 8:45 p.m.: The latest images from New Horizons depict Charon’s chasms—one of which is deeper and longer than the Grand Canyon—and craters. More from National Geographic’s Nadia Drake here.
Update, 7/12: Just FYI, the New Horizons team really does not care whether you call Pluto a planet or a dwarf planet:
“NASA’s position is really quite simple: We do not care what we call this. At all.” — Jim Green #Plutoflyby
— Nadia Drake (@nadiamdrake) July 12, 2015
Update, 7/11: Just 2.5 million miles from Pluto, New Horizons snapped a photo of the side of Pluto that faces Charon. The image features four dark spots below a dark equatorial belt. These spots interest scientists because they’re so irregularly shaped, but somehow regularly spaced. Read more here.
Update, 7/9: Pluto begins to reveal discrete geologic features, seen from 3.3 million miles away.
Update, 7/8: New map of Pluto shows a 1,860-mile-long dark blob, nicknamed “the whale,” and a bright “donut,” stretching 200 miles.
Some outside coverage of the Pluto mission so far:
- A visual guide to the historic mission, from Alexandra Witze at Nature News
- “Almost Time for Pluto’s Close-Up,” an in-depth longread from The New York Times’ space-master, Kenneth Chang
- National Geographic’s cover story on the flyby, written by Nadia Drake
- A briefer on the mission’s recent hiccup, reported by Kate Tobin for PBS NewsHour
- Edgar B. Herwick III, reporting for WGBH News on the weirdness we can expect from Pluto
Speaking of what to expect, here is NOVA’s preview of the mission: