Published: Mon, February 11, 2019
Research | By Raquel Erickson

NASA's faraway space snowman has flat, not round, behind

NASA's faraway space snowman has flat, not round, behind

Ultima Thule, more formally named 2014 MU69, is Kuiper Belt Object (KBO), is so far the most distant world ever explored in our solar system.

Project scientist Hal Weaver of Johns Hopkins University, home to New Horizons flight control center, said the finding should spark new theories on how such primitive objects formed early in the solar system.

"The shape model we have derived from all of the existing Ultima Thule imagery is remarkably consistent with what we have learned from the new crescent images", said New Horizons co-investigator Simon Porter. The "old view" in this illustration is based on images taken within a day of New Horizons' closest approach to the Kuiper Belt object on January 1, 2019, suggesting that both of "Ultima" (the larger section, or lobe) and "Thule" (the smaller) were almost ideal spheres just barely touching each other.

"Seeing more data has significantly changed our view", Southwest Research Institute's Alan Stern, the lead scientist, said in a statement.

The larger lobe, nicknamed "Ultima", more closely resembles a giant pancake, and the smaller lobe, nicknamed "Thule", is shaped like a dented walnut, according to the mission team.

'But more importantly, the new images are creating scientific puzzles about how such an object could even be formed. "We've never seen anything like this orbiting the Sun".

Ultima Thule has shown this new side of itself because New Horizons took its final images from a different angle than the one used as it approached the object.


NASA composed this new model by observing Ultima Thule over time, watching which background stars blinked out and which did not as the asteroid rotated.

"The first close-up images of Ultima Thule - with its two distinct and, apparently, spherical segments - had observers calling it a "snowman, '" the government space agency said". The photos were taken almost 10 minutes after the probe passed its closest point to the rock.

The newest sequence of images suggests that instead of two spheres, MU69's sections (called "lobes") are somewhat flat.

Photos don't lie but they can't be a bit misleading, even in space. "Nothing quite like this has ever been captured in imagery". The images reveal an outline of the "hidden" portion of the Ultima Thule that was not illuminated by the Sun as the spacecraft zipped by, but can be "traced out" because it blocked the view to background stars also in the image.

New Horizons flew within 2,200 miles of MU69, travelling at a speed of 32,200 mph. As it's situated in the Kuiper Belt about 4.1 billion miles from Earth, there's much about MU69 that scientists are still learning.

The discovery of MU69's considerably more svelte dimensions has scientists scratching their heads on how the shape of the thing fits in with current thinking on planetary formation.

But it will take about 20 months for New Horizons to send all of the images it captured back to Earth, and scientists' understanding of the rock is changing as fresh perspectives get revealed.

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