On July 14th, 2015, the New Horizons made the first-ever flyby of Pluto. As if that wasn’t enough, the mission made history again with the flyby of the Kuiper Belt Object (KBO) 2014 MU69 on December 31st, 2018. This constituted the farthest encounter from Earth with a celestial object, which the team had nicknamed Ultima Thule – a mythical northern island beyond the borders of the known world in Medieval literature.
Unfortunately, this name has generated some controversy due to the fact that it is also the name white supremacists use to refer to a mythical homeland. So with the consent of the tribal elders and representatives of the Powhatan nations, the New Horizons’ team recommended a new name for the KBO. Henceforth, it will be known as “Arrokoth“, the word for “sky” in the Powhatan/Algonquian language.
On December 31st, 2018, the New Horizons probe conducted the first flyby in history of a Kuiper Belt Object (KBO). Roughly half an hour later, the mission controllers were treated to the first clear images of Ultima Thule (aka. 2014 MU69). Over the course of the next two months, the first high-resolution images of the object were released, as well as some rather interesting findings regarding the KBOs shape.
Just recently, NASA released more new images of Ultima Thule, and they are the clearest and most detailed to date! The images were taken as part of what the mission team described as a “stretch goal”, an ambitious objective to take pictures of Ultima Thule mere minutes before the spacecraft made its closest approach. And as you can no doubt tell from the pictures NASA provided, mission accomplished!
On December 31st, 2018, NASA’sNew Horizons mission made history by being the first spacecraft to rendezvous with the Kuiper Belt Object (KBO) named Ultima Thule (2014 MU69). This came roughly two and a half years after New Horizons became the first mission in history to conduct a flyby of Pluto. This latest encounter led to some stunning images of the KBO as the spacecraft made it’s approach.
But of course, these were not the last images New Horizons was going to capture of this object. While making its flyby of Ultima Thule on New Year’s Day, the spacecraft took a number of images that revealed something very interesting about Ultima Thule’s shape. Rather than consisting of two spheres that are joined together, Ultima Thule is actually made up of two segments – one that looks like a pancake, the other a walnut.
Since it made its historic flyby of Pluto in July of 2015, the New Horizons mission has been venturing farther into the outer Solar System. With the spacecraft still healthy and its system in working order, the mission was extended to include the exploration of additional Kuiper Belt Objects (KBOs). The first target for this part of its mission is the KBO known as 2014 MU69, which New Horizons is currently making its way towards.
In the past, NASA believed this object was a spherical chunk of ice and rock measuring 18–41 km (10–30 mi) in diameter. However, a more recent occultation observation has led the New Horizon‘s team to conclude that MU69 may actually be a large object with a chunk taken out of it (an “extreme prolate spheroid”) or two objects orbiting very closely together or touching – aka. a close or contact binary.
In 2015, MU69 was identified as one of two potential destinations for New Horizons and was recommended to NASA by the mission science team. It was selected because of the immense opportunities for research it presented. As Alan Stern, the Principle Investigator (PI) for the New Horizons mission at the Southwest Research Institute (SwRI), indicated at the time:
“2014 MU69 is a great choice because it is just the kind of ancient KBO, formed where it orbits now, that the Decadal Survey desired us to fly by. Moreover, this KBO costs less fuel to reach [than other candidate targets], leaving more fuel for the flyby, for ancillary science, and greater fuel reserves to protect against the unforeseen.”
The most recent observation of the KBO took place on July 17th, 2017, when the object passed in front of a star. This provided the New Horizon’s team with an opportunity to measure the resulting dip in the star’s luminosity – aka. an occultation – using a series of telescopes that they had deployed to a remote part of Patagonia, Argentina. These sorts of observations are performed regularly in order to obtain estimates of an asteroid’s size and position.
In the case of MU69’s occulation, the New Horizons team was able to obtain vital data that will help the mission planners to plot the trajectory of their flyby. In addition, the data revealed things about MU69’s size, shape, orbit, and the environment that surrounds it. It was because of this that the team began to question earlier estimates on the object’s size and shape.
Based on their new observations, they are confident that the object is no more than 30 km (20 mi) long, if it is an extreme prolate spheroid. If, however, it is a binary, the two objects that compose it are believed to measure about 15-20 km (9-12 mi) in diameter each. Alan Stern expanded on these new findings in a recent NASA press statement, saying:
“This new finding is simply spectacular. The shape of MU69 is truly provocative, and could mean another first for New Horizons going to a binary object in the Kuiper Belt. I could not be happier with the occultation results, which promise a scientific bonanza for the flyby.”
The recent stellar occulation was the third of three observations conducted for the New Horizons mission. To prepare for the event, the New Horizons team traveled to Argentina and South Africa on June 3rd. On July 10th, a week before the occultation, NASA’s airborne Stratospheric Observatory for Infrared Astronomy (SOFIA) provided support by studying the space around MU69.
Using its 2.5 m (100-inch) telescope, SOFIA was looking for debris that might present a hazard to New Horizons spacecraft as it makes its flyby less than 17 months from now. Last, but certainly not least, the team also relied on data provided by NASA’s Hubble Space Telescope and the ESA’s Gaia satellite to calculate and pinpoint where MU69 would cast its shadow on Earth’s surface.
Thanks to their assistance, the New Horizons team knew exactly where the occultation shadow would be and set up their “fence line” of small, mobile telescopes accordingly. Marc Buie – the New Horizons co-investigator – was responsible for leading the observation campaign. As he explained, the data it yielded will be of great help in the planning the flyby, but also indicated that their could be some surprises in the future:
“These exciting and puzzling results have already been key for our mission planning,” he said, “but also add to the mysteries surrounding this target leading into the New Horizons encounter with MU69, now less than 17 months away.”
The flyby with MU69 is scheduled to take place on Jan. 1st, 2019, and will be the most distant flyby in the history of space exploration. In addition to being 1.6 billion km (1 billion mi) from Pluto, the New Horizons spacecraft will be 6.5 billion km (4 billion mi) from Earth! What’s more, the first-ever study of a KBO is expected to yield some fantastic scientific data, and tell us much about the formation and evolution of our Solar System.
While the New Horizons spacecraft was heading to Pluto, scientists from the mission used Hubble and other telescopes to try and find out more about the environment their spacecraft would be flying through. No one wanted New Horizons to run into unexpected dust or debris.
And now, as New Horizons prepares to fly past its next target, the Kuiper Belt Object known as 2014 MU69, mission scientists are using every tool at their disposal to examine this object and the surrounding region. The flyby will take place on January 1, 2019.
They’ve already uncovered some surprises.
On June 3, 2017, 2014 MU69 passed in front of a star – in an event called an occultation – providing a two-second glimpse of the object’s shadow.
More than 50 mission team members and collaborators traveled to South Africa and Argentina to catch the occultation, setting up telescopes to capture the event. They are now looking through more than 100,000 images of the occultation star that can be used to assess the environment around this Kuiper Belt object (KBO). In addition, the Hubble Space Telescope and Gaia, a space observatory of the European Space Agency (ESA) also observed the event.
The team said that while MU69 itself eluded direct detection, the June 3 data provided valuable and unexpected insights that have already helped New Horizons.
“These results are telling us something really interesting,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute. “The fact that we accomplished the occultation observations from every planned observing site but didn’t detect the object itself likely means that either MU69 is highly reflective and smaller than some expected, or it may be a binary or even a swarm of smaller bodies left from the time when the planets in our solar system formed.”
Mission scientist Simon Porter said on Twitter, “The upshot is that MU69 is probably not as big and dark as it could have been, and (more importantly) doesn’t seem to have rings or a dust cloud,” adding later that the “lack of dust was reassuring.”
Again, no one wants to New Horizons to run into any surprising dust or debris.
The team will be observing two more occultation events on July 10 and July 17, and Porter said they should get even better constraints from these next two events.
On July 10, NASA’s airborne Stratospheric Observatory for Infrared Astronomy (SOFIA) will use its 100-inch (2.5-meter) telescope to probe the space around MU69 for debris that might present a hazard to New Horizons as it flies by in 18 months.
On July 17, the Hubble Space Telescope also will check for debris around MU69, while team members set up another ground-based “fence line” of small mobile telescopes along the predicted ground track of the occultation shadow in southern Argentina to try to better constrain, or even determine, the size of MU69.
Initial estimates of MU69’s diameter, based primarily on data taken by the Hubble Space Telescope since the KBO’s discovery in 2014, fall in the 12-25-mile (20-40-kilometer) range. However, the latest data from the June occultation seem to imply it’s at or even below the smallest estimated sizes.
“2014 MU69 is a great choice because it is just the kind of ancient KBO, formed where it orbits now, that the Decadal Survey desired us to fly by,” Stern said back in August 2015 when the target was announced. “Moreover, this KBO costs less fuel to reach [than other candidate targets], leaving more fuel for the flyby, for ancillary science, and greater fuel reserves to protect against the unforeseen.”
You can see the star brightness, predicted shadow path and other tech specs for the July 10 and July 17 occultation events at the embedded links.
It isn’t every day we get a new moon added to the list of solar system satellites. The combined observational power of three observatories — Kepler, Herschel and Hubble — led an astronomical detective tale to its climatic conclusion: distant Kuiper Belt Object 2007 OR10has a tiny moon.
The dwarf planet itself is an enigma wrapped in a mystery: with a long orbit taking it out to a distant aphelion 101 astronomical units (AU) from the Sun, back into the environs of Neptune and Pluto for a perihelion 33 AU from the Sun once every 549 years, 2007 OR10 was discovered by Caltech astronomers Megan Schwamb and Mike Brown in 2007. Nicknamed “Snow White” by Mike Brown for its presumed high albedo, 2007 OR10 was 85 AU distant in the constellation Aquarius at the time of discovery and outbound towards aphelion in 2135. 2007 OR10 is about 1,500 kilometers in diameter, the third largest body known beyond Neptune in our solar system next to Pluto and Eris (nee Xena).
Enter the Kepler Space Telescope, which imaged 2007 OR10 crossing the constellation Aquarius as part of its extended K2 exoplanet survey along the ecliptic plane. Though Kepler looks for transiting exoplanets — worlds around other stars that betray their presence by tiny dips in the brightness of their host as they pass along our line of sight — it also picks up lots of other things that flicker, including variable stars and distant Kuiper Belt Objects. But the slow 45 hour rotational period of 2007 OR10 noted by Kepler immediately grabbed astronomers interest: could an unseen moon be lurking nearby, dragging on the KBO like a car brake?
“Typical rotation periods for Kuiper Belt Objects are under 24 hours,” says Csaba Kiss (Konkoly Observatory) in a recent press release. “We looked in the Hubble archive because the slower rotation period could have been caused by the gravitational tug of a moon.”
And sure enough, digging back through archival data from the Hubble Space Telescope taken during a survey of KBOs, astronomers turned up two images of the faint moon from 2009 and 2010. Infrared observations of 2007 OR10 and its moon by the European Space Agency’s Herschel Space Telescope cinched the discovery, and noted an albedo of 19% (similar to wet sand) for 2007 OR10, much darker than expected. The moon is about 200 miles (320 kilometers) in diameter, in a roughly 9,300 mile (15,000 kilometer) orbit.
The discovery was announced at an AAS meeting just last year, and even now, we’re still puzzling out what little we know about these distant worlds. Just what 2007 OR10 and its moon looks like is any guess. New Horizons gave us our first look at Pluto and Charon two short summers ago in 2015, and will give us a fleeting glimpse of 2014 MU69 on New Year’s Day 2019. All of these objects beg for proper names, especially pre-2019 New Horizons flyby.
What would the skies from the tiny moon look like? Well, ancient 2007 OR10 must loom large in its sky, though Sol would only shine as a bright -15th magnitude star, (a little brighter than a Full Moon) its illumination dimmed down to 1/7,000th the brightness enjoyed here on sunny Earth, which would be lost in its glare.
And looking at the strange elliptical orbits of these outer worldlets, we can only surmise that something else must be out there. Will the discovery of Planet 9 be made before the close of the decade?
One thing’s for sure: this isn’t your parent’s tidy solar system with “Excellent Mothers” serving “Nine Pizzas.”
The New Horizons probe made history in July of 2015, being the first mission to ever conduct a close flyby of Pluto. In so doing, the mission revealed some never-before-seen things about this distant world. This included information about its many surface features, it’s atmosphere, magnetic environment, and its system of moons. It also provided images that allowed for the first detailed maps of the planet.
Having completed its rendezvous with Pluto, the probe has since been making its way towards its first encounter with a Kuiper Belt Object (KBO) – known as 2014 MU69. And in the meantime, it has been given a special task to keep it busy. Using archival data from the probe’s Long Range Reconnaissance Imager (LORRI), a team of scientists is taking advantage of New Horizon‘s position to conduct measurements of the Cosmic Optical Background (COB).
The COB is essentially the visible light from other galaxies which shines beyond the edge of the Milky Way. By measuring this light, astronomers are able to learn a great deal about the locations of stars, the size and density of galaxies, and test theories about the structure and formation of the Universe. This is no easy task, mind you, as any measurements conducted from inside the Solar System are subject to interference.
Whereas Earth-based telescopes experience interference from our atmosphere, space-based telescopes have to contend with the brightness of our Sun. In addition, interplanetary dust (IPD) has the effect of scattering light in the Solar System (known as Zodiacal Light) which can also obscure light coming from distant sources. But a probe like New Horizons, which is well into the outer Solar System, is not subject to such interference.
For the sake of this study, the team analyzed LORRI data obtained during NH’s cruise phase between Jupiter and Uranus. After using data from four different isolated fields in the sky (captured between 2007 and 2010), the team was able to obtain a statistical upper limit on the optical background’s brightness.
“This result shows some of the promise of doing astronomy from the outer solar system. What we’re seeing is that the optical background is completely consistent with the light from galaxies and we don’t see a need for a lot of extra brightness; whereas previous measurements from near the Earth need a lot of extra brightness. The study is proof that this kind of measurement is possible from the outer solar system, and that LORRI is capable of doing it.”
Their results also showed that earlier measurements conducted by Hubble’s Wide Field Planetary Camera 2 were excessively bright (owing to interference). However, their results were consistent with previous measurements that were based on data obtained by the Pioneer 10 and 11 missions. Back in the 1970s, these probes managed to gather data on the Universe while swinging past Jupiter and exploring the outer Solar System.
By showing consistency with these results (and other measurements from over the years), the team demonstrated just how valuable missions like New Horizons are. It is hoped that before it wraps up in 2021, that scientists will have a chance to conduct more measurements of the COB. Considering how rare missions to the outer Solar System are, it is understandable why Zemcov and his colleagues want to take full advantage of this opportunity.
“NASA sends missions to the outer Solar System once a decade or so,” he said. “What they send is typically going to planets and the instruments onboard are designed to look at them, not to do astrophysics. Measurements could be designed to optimize this technique while LORRI is still functioning… With a carefully designed survey, we should be able to produce a definitive measurement of the diffuse light in the local universe and a tight constraint on the light from galaxies in the optical wavebands.”
In other mission-related news, New Horizons probe will be taking a nap as it approaches its next destination – 2014 MU69. On Friday, April 7th, at 15:32 EDT, mission controllers at the John Hopkins University APL verified that the probe had entered hibernation. It will remain in this state for the next 157 days, waking up again on September 11th, 2017, as it makes its approach to 2014 MU69.
Originally, the New Horizons mission was scheduled to end after its historic encounter with Pluto. However, the mission was extended shortly thereafter to 2021 so the probe would also be able to make some more historic encounters. If, in the meantime, this probe can also shed new light on the mysteries of the Universe, it will surely be remembered as one of the most groundbreaking missions of all time.
Sometimes, its not the eye candy aspect of the image, but what it represents. A recent image of Pluto’s large moon Charon courtesy of New Horizons depicting what could only be termed ‘Plutoshine’ caught our eye. Looking like something from the grainy era of the early Space Age, we see a crescent Charon, hanging against a starry background…
So what, you say? Sure, the historic July 14th , 2015 flyby of New Horizons past Pluto and friends delivered images with much more pop and aesthetic appeal. But look closely, and you’ll see something both alien and familiar, something that no human eye has ever witnessed, yet you can see next week.
We’re talking about the reflected ‘Plutoshine‘ on the dark limb of Charon. This over-exposed image was snapped from over 160,000 kilometers distant by New Horizons’ Ralph/Multispectral imager looking back at Charon, post flyby. For context, that’s just shy of half the distance between the Earth and the Moon. “Bigger than Texas” (Cue Armageddon), Charon is about 1200 kilometers in diameter and 1/8th the mass of Pluto. Together, both form the only true binary (dwarf) planetary pair in the solar system, with the 1/80th Earth-Moon pair coming in at a very distant second.
We see reflected sunlight coming off of a gibbous Pluto which is just out of frame, light that left the Sun 4 hours ago and took less than a second to make the final Pluto-Charon-New Horizons bounce. You can see a similar phenomenon next week, as Earthshine or Ashen Light illuminates the otherwise dark nighttime side of the Earth’s Moon, fresh off of passing New phase this weekend. Snow and cloud cover turned Moonward can have an effect on how bright Earthshine appears. One ongoing study based out of the Big Bear Solar observatory in California named Project Earthshine seeks to characterize long-term climate variations looking at this very phenomenon.
Standing on Pluto, you’d see a 3.5 degree wide Charon, 7 times larger than our own Full Moon. Of course, you’d need to be standing in the right hemisphere, as Pluto and Charon are tidally locked, and keep the same face turned towards each other. It would be a dim view, as the Sun shines at -20 magnitude at 30 AU distant, much brighter than a Full Moon, but still over 600 times fainter than sunny Earth. Dim Plutoshine on the nightside of Charon would, however, be easily visible to the naked eye.
A small 6 cm instrument, Ralph images in the visual to near-infrared range. Ralph compliments New Horizons larger LORRI instrument, which has a diameter and very similar optical configuration to an amateur 8-inch Schmidt-Cassegrain telescope.
Don’t look for Pluto now; it just passed solar conjunction on the far side of the Sun on January 7th, 2017. Pluto reaches opposition and favorable viewing for 2017 on July 10th, one of the 101 Astronomical Events for 2017 that you’ll find in our free e-book, out from Universe Today.
And for an encore, New Horizons will visit the 45 kilometer in diameter Kuiper Belt Object 2014 MU69 on New Year’s Day 2019. From there, New Horizons will most likely chronicle the environs of the the distant solar system, as it joins Pioneer 10 and 11 and Voyagers 1 and 2 as human built artifacts cast adrift along the galactic plane.
And to think, it has taken New Horizons about 18 months for all of its flyby data to trickle back to the Earth. Enjoy, as it’ll be a long time before we visit Pluto and friends again.
What an age we live in. This summer marks the very first opposition of Pluto since New Horizons’ historic flyby of the distant world in July 2015. If you were like us, you sat transfixed during the crucial flyby phase, the climax of a decade long mission. We now live in an era where Pluto and its massive moon Charon are a known worlds, something that even Pluto discoverer Clyde Tombaugh never got to see.
Pluto in 2016
And this summer, with a little skill and patience and a good-sized telescope, you can see Pluto for yourself. Opposition 2016 sees the remote world looping through the star-rich fields of eastern Sagittarius. Hovering around declination 21 degrees south, +14.1 magnitude Pluto is higher in the June skies for observers in the southern hemisphere than the northern, but don’t let that stop you from trying. Opposition occurs on July 7th, when Pluto rises opposite from the setting Sun and rides across the meridian at 29 degrees above the southern horizon for observers based along 40 degrees north latitude at local midnight.
Pluto actually crossed the plane of the galactic equator in 2009, and won’t cross the celestial equator northward until 2109. Fun fact: astronomer Clyde Tombaugh discovered Pluto as it drifted through the constellation Gemini in 1930. Here we are 86 years later, and Pluto has only moved six zodiacal constellations along the ecliptic eastward in its 248 year orbit around the Sun.
And Pluto is getting tougher to catch in a backyard scope, as well. The reason: Pluto passed perihelion or its closest point to the Sun in 1989 inside the orbit of Neptune, and it’s now headed out to aphelion about a century from now in 2114. Pluto is in a fairly eccentric orbit, ranging from 29.7 astronomical units (AU) to 49.4 AU from the Sun. This also means that Pluto near opposition can range from a favorable magnitude +13.7 near perihelion, to three magnitudes (16 times) fainter near aphelion hovering around magnitude +16.3. Clyde was lucky, in a way. Had Pluto been near aphelion in the 20th century rather than headed towards perihelion, it might have waited much longer for discovery.
2016 sees Pluto shining at +14.1, one magnitude (2.5 times) above the usual quoted mean. See Mars over in the constellation Libra shining at magnitude -1.5? It’s 100^3 (a 5-fold change in magnitude is equal to a factor of 100 in brightness), or over a million times brighter than Pluto.
You often see Pluto quoted as visible in a telescope aperture of ‘six inches or larger,’ but for the coming decade, we feel this should be amended to 8 inches and up. We once nabbed Pluto during public viewing using the 14” reflector at the Flandrau observatory.
And how about Pluto’s large moon, Charon? Shining at an even fainter +16th magnitude, Charon never strays more than 0.9” from Pluto… still, diligent amateurs have indeed caught the elusive moon… as did Wendy Clark just last year.
Lacking a telescope? Hey, so are we, as we trek through Morocco this summer… never fear, you can still wave in the general direction of Pluto and New Horizons on the evening of June 21st, one day after the northward solstice and the Full Moon, which passes three degrees north of Pluto.
And follow that spacecraft, as New Horizons is set to make a close pass by Kuiper Belt Object 2014 MU69 in January 2019 on New Year’s Day.
A key date to make your quest for Pluto is June 26th, when Pluto sits just 3′ minutes to the south of the +2.9 magnitude star Pi Sagittarii (Albaldah), making a great guidepost.
Does the region of Sagittarius near Pi Sagittarii sound familiar? That’s because the Wow! Signal emanated from a nearby region of the sky on August 15th, 1977. Pluto will cross the border into the constellation Capricornus in 2024.
After opposition, Pluto heads into the evening sky, towards solar conjunction on January 7th, 2017.
Observing Pluto requires patience, dark skies, and a good star chart plotted down to about +15th magnitude. One key problem: many star charts don’t go down this faint. We use Starry Night Pro 7, which includes online access to the USNO catalog and a database of 500 million stars down to magnitude +21, more than enough for most backyard scopes.
Don’t miss a chance to see Pluto for yourself this summer!
Just like Luke and Leia, two craters named for the Star Wars twins (Skywalker and Organa) have many similarities. They look about the same size and shape, and appear to have been created at the same time, and therefore are about the same age. But instruments on the New Horizons spacecraft detected one major difference: Organa and its surrounding area are laced with ammonia.
“Why are these two similar-looking and similar-sized craters, so near to each other, so compositionally distinct?” asked Will Grundy, who leads the New Horizons Composition team. “We have various ideas when it comes to the ammonia in Organa. The crater could be younger, or perhaps the impact that created it hit a pocket of ammonia-rich subsurface ice. Alternatively, maybe Organa’s impactor delivered its own ammonia.”
Both craters are roughly 5 kilometers (3 miles) in diameter, with similar appearances, such as bright rays of ejecta. One apparent difference is that Organa has a central region of darker ejecta, though from the map created with data from New Horizons’ Ralph/LEISA instrument, it appears that the ammonia-rich material extends beyond this dark area.
The nearby Skywalker crater, however, shows an infrared spectrum that is similar to the rest of Charon’s craters and surface, with features mostly dominated by ordinary water ice.
“This is a fantastic discovery,” said Bill McKinnon, deputy lead for the New Horizons Geology, Geophysics and Imaging team. “Concentrated ammonia is a powerful antifreeze on icy worlds, and if the ammonia really is from Charon’s interior, it could help explain the formation of Charon’s surface by cryovolcanism, via the eruption of cold, ammonia-water magmas.”
The New Horizons team is informally naming features after various sci-fi characters. So maybe – like their Star Wars namesakes – the craters Skywalker and Organa actually are different ages, as students at the University of Leicester calculated in a paper published earlier this year. The students said that Leia would be about 2 years old than Luke because of relative velocity time dilation – which describes the bending of spacetime due to differences in speed. Their different journeys through space in various craft would change how fast they are aging.
But we digress…
Meanwhile, as New Horizons continues to send back more imagery and data, the spacecraft’s hydrazine-fueled thrusters completed the third of four maneuvers to direct the spacecraft towards an ancient and distant Kuiper Belt Object named 2014 MU69.
As we explained in our previous article, the four maneuvers are designed change New Horizons’ path to send it toward a close encounter with the KBO on Jan. 1, 2019. Even though the New Horizons spacecraft hasn’t officially been approved to do this flyby as an extended mission, the team is taking advantage of being able to do the maneuvers early, thereby saving fuel.
The science team hopes to bring the spacecraft even closer to MU69 than it came to Pluto this summer, which was approximately 7,750 miles (12,500 kilometers)
The fourth and final KBO targeting maneuver is scheduled for next week, Nov. 4, 2015.
Another image released this week from the New Horizons team:
In September, the New Horizons team released a stunning but incomplete image of Pluto’s crescent. Thanks to new processing work by the science team, New Horizons is releasing the entire, breathtaking image of Pluto.
Alex Parker, one of the science team members who worked on the image said on Twitter, “The haze over Pluto’s dark limb were frustratingly run through with instrumental artifacts. This version is my latest destripe and denoise.” He also noted a few things: look closely, and you can see background stars behind Pluto. Additionally, look at Pluto’s shadowed limb:
Another wonderful thing about that new image: the bright haze gives us a look at how bumpy Pluto's shadowed limb is! pic.twitter.com/hUSGIZB8Bw