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A Closer Look at Ultima Thule

“We think we are looking at the most primitive object ever imaged by a spacecraft,” said Jeff Moore (NASA Ames) at today’s Ultima Thule press conference. Moore, New Horizons geology and geophysics lead, went on to describe the process of innumerable particles growing into nodes amidst growing low velocity collision and interaction. We are truly looking at primordial materials with Ultima Thule, which is now revealed as a contact binary. Have a look.

Image: This image taken by the Long-Range Reconnaissance Imager (LORRI) is the most detailed of Ultima Thule returned so far by the New Horizons spacecraft. It was taken at 5:01 Universal Time on January 1, 2019, just 30 minutes before closest approach from a range of 18,000 miles (28,000 kilometers), with an original scale of 730 feet (140 meters) per pixel. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

Bear in mind that New Horizons was working with a Sun 1,900 times fainter than a sunny day on Earth, as mission principal investigator Alan Stern reminded the audience when he unveiled the image above. “It’s a snowman, not a bowling pin,” joked Stern as the image was displayed. Bear in mind as well that these early images are just the beginning. The mission team has now downloaded less than 1 percent of the data available on the spacecraft’s solid state recorders.

One of Jeff Moore’s slides:

And here’s the slide Moore showed to illustrate the process of accretion:

Putting these two lobes together would, Moore said, be gentle enough that “…if you were in a car collision at this speed you wouldn’t bother to fill out the insurance forms.” These are high-Sun images, meaning we see little shadow, but the Sun angle will change as we move into later views at higher resolution. Even so, note the absence of obvious impact craters, and the mottled suggestions of hills and ridges. Also note the brightness of the ‘neck’ between the lobes.

Image: The first color image of Ultima Thule, taken at a distance of 85,000 miles (137,000 kilometers) at 4:08 Universal Time on January 1, 2019, highlights its reddish surface. At left is an enhanced color image taken by the Multispectral Visible Imaging Camera (MVIC), produced by combining the near infrared, red and blue channels. The center image taken by the Long-Range Reconnaissance Imager (LORRI) has a higher spatial resolution than MVIC by approximately a factor of five. At right, the color has been overlaid onto the LORRI image to show the color uniformity of the Ultima and Thule lobes. Note the reduced red coloring at the neck of the object. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

Ultima Thule’s rotation period is currently pegged at 15 hours, plus or minus an hour. The object turns out to be red, as expected. As to reflectivity, deputy project scientist Kathy Olkin (SwRI) pointed out that the brightest areas reflect about 13 percent of incident sunlight, the darkest areas only 6 percent. Ultima Thule is, in other words, very dark, as dark as potting soil, Olkin added, with significant variation across the surface.


Comments on this entry are closed.

  • Carl Keller January 2, 2019, 19:26

    The image is reminiscent of artistic renditions depicting Theia’s impact with our ancient Earth.

    • jonW January 3, 2019, 0:51

      Your comment made me think the following: I understand it would be impossible, but isn’t it fun to imagine a habitable-zone Earth-plus-Theia-sized pair “colliding” at such low speeds early on in a solar-system’s formation, and retaining such a bi-lobed composite shape, even while intelligent life and civilisations arose on it/them? Imagine the geo-political ramifications, not to mention the cartographers’ difficulties! (But I suppose we shouldn’t try too hard to imagine the geological and meteorological consequences if we want to continue to suspend disbelief.)

      I predict bi-lobed worlds will appear soon in sci-fi, now that the world’s attention has been drawn to MU69.

      • Ron S. January 3, 2019, 10:42

        Sorry, but no. As the mass rises the asymmetries are removed by gravitational collapse. Indeed that’s why this is used as one of the criteria for labeling a body as a planet.

        • jonW January 3, 2019, 18:55

          yes, hence my prefacing the whole thing with “I understand it would be impossible, but…”

          • Ron S. January 3, 2019, 23:02

            Obviously I read that too quickly and missed the key words. My bad.

      • ljk January 3, 2019, 10:45

        There is Rocheworld by Robert Forward, published in 1982 (and later as Flight of the Dragonfly in 1984):


        The exoworlds orbit Barnard’s Star and a human crewed mission goes there via laser-driven light sail.

        • Patient Observer January 3, 2019, 17:50

          Roceworld was very entertaining with as much hard science as anyone could want in an interstellar story. The two worlds were not quite touching but did share a common atmosphere. I thought that the author did not explore interpersonal issues within the crew that would undoubtedly arise during a multiple decades mission but, otherwise, it was a great read.

          • ljk January 4, 2019, 10:02

            I respect the heck out of Robert Forward, but the characters in his SF novels tended to lack a certain amount of realism. His novels were obviously vehicles to display his scientific and technological ideas. Werner von Braun did the same thing with a novel he wrote in 1952 about a manned expedition to Mars.

  • Andrew Whittaker Percival January 2, 2019, 22:10

    So exciting to see world grow from discovery, to a few pixels to a more coherent object!
    As ever, I think about uses for new things we find and I wonder how useful these little frozen chunks are to the Inner Solar System?
    From Belt colonies to Terraforming Mars to feeding Earths’ insatiable desire for resources, is there “cold gold” out there?

    • ljk January 4, 2019, 10:12

      Some day the society beyond science fiction and hardcore space fans are going to recognize the immense value of having billions (trillions?) of floating chunks of raw resources floating all over our Sol system. We just need to get beyond Earth in both the literal and sociological sense.

  • Thomas W. Hair January 3, 2019, 0:16

    The most powerful thing in the visible universe is not a billion sol black hole, as far as we can see it is the human mind and what it discovers.

  • Adam January 3, 2019, 5:18

    Almost makes me think of dough… planet dough.

  • Michael January 3, 2019, 10:50

    I seem too see two faces, one in the smaller and one in the larger.

    • ljk January 4, 2019, 10:08

      That’s what your ancient hardwired genetics are designed to do.

  • ljk January 3, 2019, 10:52

    So Ultima Thule is now being known as Ultima and Thule, to differentiate the two connected lobes.


    Ultima and Thule

    Image Credit: NASA, Johns Hopkins University APL, Southwest Research Institute

    Explanation: On January 1 New Horizons encountered the Kuiper Belt object nicknamed Ultima Thule. Some 6.5 billion kilometers from the Sun, Ultima Thule is the most distant world ever explored by a spacecraft from Earth.

    This historic image, the highest resolution image released so far, was made at a range of about 28,000 kilometers only 30 minutes before the New Horizons closest approach.

    Likely the result of a gentle collision shortly after the birth of the Solar System, Ultima Thule is revealed to be a contact binary, two connected sphere-like shapes held in contact by mutual gravity.

    Dubbed separately by the science team Ultima and Thule, the larger lobe Ultima is about 19 kilometers in diameter. Smaller Thule is 14 kilometers across.

    • megaprimatus kong January 15, 2019, 23:38

      Strange , how the objects were designated Mu-69 ,one of the lanthanide series of chemical elements with atomic numbers .

      If those objects weren’t fused , damned if they don’t resemble my thought of some binary pulsars .

  • ljk January 3, 2019, 11:06

    Emily Lakdawalla • January 2, 2019

    MU69 appears as a bi-lobed baby comet in latest New Horizons images

    How do contact binaries form?

    The tiny world 2014 MU69 is far behind New Horizons now and no longer visible to its cameras. Now, New Horizons’ task is to return its precious data to Earth. The process will take 20 months, but the best images should all arrive between now and the end of February. Some early ones have come down from the spacecraft in the hours since the flyby. These are not the best we will get, but they already show us much about MU69: this is probably what comets look like, before they become comets. (Note: the press briefing is still going on; I’ll continue to add images to this post throughout the morning.)

    Full article here:


    • Harry R Ray January 4, 2019, 11:35

      Two statements from NASA have left me rather confused. One, they stated that Ultima Thule is the first contact binary object ever visited by spacecraft. What about the bilobed comet 67P? Two, they stated that there appears to be no visible craters. What about the fascinating feature I call Occator Junior(due to its striking resemblance to Ceres’ Occator crater on the smaller of the two lobes? To me, it appears to be an obvious depression of some kind, or: am I seeing things improperly due to the shapes of the two contrasting features of a low albedo “ring” exterior to the region containing the two high albedo spots?

      • ljk January 4, 2019, 14:51

        On the first issue they are obviously wrong. Comet 67P is a contact binary, as is Halley’s Comet, as just two of the more prominent examples.

        On the latter issue, the “no craters” declaration is likely premature based on the quality of the images we have at present.

      • Andrei January 6, 2019, 16:54

        Yes I wondered too about ‘first contact binary’ we have seen many images up close of Churyumov–Gerasimenko, Halley, 19P Borelly and 103P Hartley.
        Elakdawalla of Planetary society got it right, public relations person of NASA is a fool.

        • ljk January 7, 2019, 10:08

          I wonder if, due to the government shutdown, NASA didn’t exactly have the cream of the crop onboard when it came to getting such facts straight? Because anyone with more than a casual knowledge of comets and planetoids knows how many of the ones we have seen up close are contact binaries.

  • ljk January 3, 2019, 14:29

    Useless Knowledge Begets New Horizons

    Fundamental discoveries don’t always have practical uses, but they have soul-saving applications.

    By Bret Stephens, Opinion Columnist

    January 3, 2019


    • Alex Tolley January 3, 2019, 19:15

      What an unusual piece by Stephens.

      • ljk January 4, 2019, 10:20

        Of course the NYT has to turn around and do a piece on the very people who just placed the first lander and rover (and ecosystem) on the lunar farside questioning the value of such a historic mission:


        • Patient Observer January 4, 2019, 15:42

          The muted reaction was a sign that the novelty of the country’s space missions has faded. But the coverage also appeared to reflect political and economic anxieties at a time when Mr. Xi’s government is trying to negotiate a truce in the trade war with the United States and respond to worrisome cracks in the economy.

          The NYT just can’t write a story about China (or Russia) without torturing the narrative to add a lot of spin. Many may like the NYT but, for me, its credibility is nil unless they are reporting on things like sports scores.

          • ljk January 4, 2019, 18:56

            Most likely China is doing in one key area what the Soviet Union used to do when reporting on one of their space missions: Being very careful about what is made public in case something is going wrong, so they don’t look bad.

            In any event, apparently it isn’t just the USA where the populace does not know how much money goes into their space program compared to other federal agencies.

        • Alex Tolley January 5, 2019, 0:22

          I am not seeing where the NYT is questioning the value of the lander. They do quote a person who is ambivalent – pride in the landing, but concerned about the cost. The Apollo program was similarly, and far more publicly, questioned about the cost (“whitey on the Moon”). I doubt that the Chinese lander was even remotely as large a fraction of GDP than the Apollo program. If they land taikonauts on the Moon, that might be a different story. I hope I am still around to see that.

          OT. What is the explanation for the “orange” color of the light in the returned images?

  • Patient Observer January 3, 2019, 17:53

    I wonder how close its rotation rate (15 hours) is to disruption. Unless there was a braking mechanism at work, it would seem that its angular momentum from its formation would be largely conserved.

  • torque_xtr January 3, 2019, 18:11

    It’s interesting how two bodies shed their angular momentum not only until contact, but even further, several times below breakup speed. Solar tides? Also how it has got it’s high inclination despite pristine form.

    • torque_xtr January 4, 2019, 18:02

      Correction, obliquity of course.

  • ljk January 4, 2019, 10:06

    Less than one week ago, Ultima (and) Thule was just a dot or blob of light at best. Now they can make GIFs and 3D images out of what New Horizons has returned to Earth.


    Ultima Thule Rotation Gif

    Image Credit: NASA, Johns Hopkins University APL, Southwest Research Institute

    Explanation: Ultima Thule is the most distant world explored by a spacecraft from Earth. In the dim light 6.5 billion kilometers from the Sun, the New Horizons spacecraft captured these two frames 38 minutes apart as it sped toward the Kuiper belt world on January 1 at 51,000 kilometers per hour. A contact binary, the two lobes of Ultima Thule rotate together once every 15 hours or so.

    Shown as a blinking gif, the rotation between the frames produces a tantalizing 3D perspective of the most primitive world ever seen. Dubbed separately by the science team Ultima and Thule, the larger lobe Ultima, is about 19 kilometers in diameter. Smaller Thule is 14 kilometers across.

  • Spaceman January 5, 2019, 12:58

    Hi Paul,

    Thank you for sharing these wonderful images! What a truly amazing accomplishment reaching this object has been for the space program. I had a question for you or anyone else on here who might know. I have seen descriptions in the popular press of Ultima Thule (UT) looking like a “red snowman” (see link below). Are any of these images representative of what UT might look like to future human explorers? What might UT look like to human explorers assuming they approach it as closely as New Horizons did?


  • ljk January 8, 2019, 10:32

    A distant flyby

    Last week, NASA’s New Horizons spacecraft flew by a small object in the Kuiper Belt, the most distant flyby by a spacecraft to date. Jeff Foust reports on the scene at mission control for the flyby and the science that will come.

    Monday, January 7, 2019


  • ljk January 8, 2019, 14:12

    Pluto Probe Encounters a Pristine World in the Solar System’s Suburbs

    Ultima Thule, the most-distant object ever visited by a spacecraft, is revealing our solar system’s deepest history—and, just maybe, revolutionizing planetary science

    By Corey S. Powell on January 8, 2019

    The history of the solar system is a dish best served cold. And it is so very cold on Ultima Thule.

    That is the message beaming back to Earth from NASA’s New Horizons probe now that it has completed its historic exploration of a small body in the Kuiper Belt, the sprawling population of dwarf planets and cometlike objects out beyond Neptune.

    When New Horizons flew past at 12:33 AM Eastern time on January 1, Ultima was a hair over four billion miles from the sun. It is by far the most distant object ever visited by spacecraft, and correspondingly one of the coldest: about 35 kelvins, or nearly 400 degrees below zero Fahrenheit.

    At such low temperatures, Ultima (more formally known by its scientific designation, 2014 MU69) preserves its initial, ancient composition. Ultima is also cold in another, more specialized and intriguing way. It is dynamically cold, part of what’s known as the “cold classical” Kuiper Belt, meaning that it circles the sun in a settled orbit that was undisturbed by all the chaotic events that buffeted Earth and other planets as they came together more than four billion years ago.

    Full article here:


    To quote:

    “We’re looking at one of the first building blocks that came together to form the planets and moons,” says Jeffrey Moore, a research scientist at NASA’s Ames Research Center. “It looks like somebody left it out in the back of God’s freezer for the last four-and-a-half billion years.”

  • ljk January 10, 2019, 14:44

    At the moment there are only three papers on ArXiv with Ultima Thule in their titles – and this is the first one that is not speculation about what the New Horizons deep space probe will find there:


    Overview of initial results from the reconnaissance flyby of a Kuiper Belt planetesimal: 2014 MU69

    S.A. Stern, J.R. Spencer, H.A. Weaver, C.B. Olkin, J.M. Moore, W. Grundy, R. Gladstone, W.B. McKinnon, D.P. Cruikshank, L.A. Young, H.A. Elliott, A.J. Verbiscer, J.Wm. Parker, the New Horizons Team

    (Submitted on 9 Jan 2019)

    The centerpiece objective of the NASA New Horizons first Kuiper Extended Mission (KEM-1) was the close flyby of the Kuiper Belt Object KBO) 2014 MU69, nicknamed Ultima Thule. On 1 Jan 2019 this flyby culminated, making the first close observations of a small KBO. Initial post flyby trajectory reconstruction indicated the spacecraft approached to within 3536 km of MU69 at 5:33:19 UT.

    Here we summarize the earliest results obtained from that successful flyby. At the time of this submission, only 4 days of data down-link from the flyby were available; well over an order of magnitude more data will be down-linked by the time of this Lunar and Planetary Science Conference presentation in 2019 March. Therefore many additional results not available at the time of this abstract submission will be presented in this review talk.

    Comments: 2 pages, 2 figures

    Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

    Cite as: arXiv:1901.02578 [astro-ph.EP]
    (or arXiv:1901.02578v1 [astro-ph.EP] for this version)

    Submission history

    From: Alan Stern [view email]

    [v1] Wed, 9 Jan 2019 01:41:17 UTC (1,569 KB)


    • wdk January 13, 2019, 13:10

      That dual column format 2 page report looks like an abstract headed for the Lunar and Planetary Science Conference in March. While some of Centauri Dreams topics will not be covered there, an abundance of “lunar and planetary” accomplishments will be. The annual is held in the Woodlands area outside of Houston,TX on the north side nearer to the Bush Airport than Hobby. (18 to 22 March 2019 – number 50!).

  • ljk January 15, 2019, 18:04

    Emily Lakdawalla • January 15, 2019

    A few new images of MU69

    New Horizons is back in action after going quiet for a period of solar conjunction following the 1 January flyby of 2014 MU69 (informally nicknamed “Ultima Thule”). The spacecraft is returning new data, as exemplified by these images, shared this morning in a tweet by principal investigator Alan Stern.

    The pictures were taken before closest approach and don’t add anything much in the way of news about the world, but: new images, woohoo!!!


    Better-quality, high-resolution images of 2014 MU69 should be available in late February, according to Stern.

  • ljk February 12, 2019, 12:11


    New Data: Ultima Thule Surprisingly Flat

    Illustration Credit: NASA, JHU’s APL, SwRI

    Explanation: Ultima Thule is not the object humanity thought that it was last month. When the robotic New Horizons spacecraft zoomed past the distant asteroid Ultima Thule (officially 2014 MU69) in early January, early images showed two circular lobes that when most simply extrapolated to 3D were thought to be, roughly, spheres.

    However, analyses of newly beamed-back images — including many taken soon after closest approach — shows eclipsed stars re-appearing sooner than expected.

    The only explanation possible is that this 30-km long Kuiper belt object has a different 3D shape than believed only a few weeks ago.

    Specifically, as shown in the featured illustration, it now appears that the larger lobe — Ultima — is more similar to a fluffy pancake than a sphere, while the smaller lobe — Thule — resembles a dented walnut. The remaining uncertainty in the outlines are shown by the dashed blue lines.

    The new shape information indicates that gravity — which contracts more massive bodies into spheres — played perhaps less of a role in contouring the lobes of Ultima Thule than previously thought. The New Horizons spacecraft continued on to Ultima Thule after passing Pluto in mid-2015. New data and images are still being received.



  • ljk February 12, 2019, 12:12

    One more…


    Makes you wonder what else we will learn about our distant celestial neighbor as the data slowly trickles back.

  • ljk February 21, 2019, 10:50

    Why does Ultima Thule seem to have so few craters?