Ultima Thule | Best View by New Horizons

The New Horizons spacecraft returned this detailed image of Ultima Thule to Earth on 18-19 Jan 2018. It was captured 7 minutes before the closest approach to Ultima Thule at a distance of 4,200 mi (6,700 km). The signal of digital bits traveled at the speed of light for 6 hrs before reaching the antenna at Earth so we could see it.


The shape of Ultima Thule was discovered in July 2017 when it passed in front of a distant star as seen from Earth. Twenty four telescopes were lined up across Argentina where the shadow of Ultima Thule was to pass as it occulted the distant star. The scopes were coordinated with precise time markers. The best-fit of their timings suggested a bi-lobed object. What an amazing prediction considering UT is only about 20 mi (30 km) across and measured from more than 4 billion miles away.

This is probably the oldest and most primordial object we will ever see in such detail.

Ultima Thule belongs to a class of Kuiper belt objects called the “Cold Classicals,” which have nearly circular orbits with low inclinations to the solar plane, and which have not been perturbed since their formation perhaps 4.6 billion years ago. Ultima Thule will therefore be the most primitive planetary object yet explored, and will reveal to us what conditions were like in this distant part of the solar system as it condensed from the solar nebula.


What’s next for New Horizons? Hopes are high for extensions to the mission into 2019 and beyond. It will take into 2020 to download all the data stored in the memory banks. With remaining fuel, New Horizons might survey the field ahead and redirect slightly to pass by other Kuiper Belt objects. Stay tuned to see what might happen.


7 thoughts on “Ultima Thule | Best View by New Horizons

  1. The ability to predict the shape of the object was only one of many amazements, but it’s one of my favorites — probably because for a non-scientist the concept of ‘shape’ was easy to grasp, even if the technical details of how the image was obtained weren’t.

    Watching the initial bits of incoming information was fascinating. Now, I’m wondering: how long do they expect to be receiving information about Ultima Thule? Given the ‘travel time’ for the data stream, I suspect it will be continuing for some time, but I’d just never thought about it.

  2. It still amazes me that 1) We can do that intercept an object that small and that far away. I sometimes can’t navigate to a new restaurant. 2) It looks like somebody kicked over a dirty snowman.

    • Good observations Jim. I’m really amazed at how well they can navigate to small objects like that. As to the dirty snowman, it would appear even much darker to your naked eye if you could be there to see it. This is an enhanced view of the dirty snowman. Thanks for stopping by always good to see you.

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