New Horizons Reaches Ultima Thule

By Jonathan Corum

New Horizons zipped past Ultima Thule at 12:33 a.m. Eastern time on New Year’s Day.

NASA received a confirmation signal from the spacecraft at 10:32 a.m. and expects to receive a low-resolution image of Ultima Thule this afternoon.

Ultima Thule lies a billion miles beyond Pluto and is thought to be an undisturbed, primitive fragment of the early solar system.

An image taken by New Horizons from 1.2 million miles away suggests that Ultima Thule is about 20 miles wide and elongated, not round.

On Christmas Eve, New Horizons’ long-range camera caught sight of Ultima Thule from a distance of 6.3 million miles.

Images of Ultima Thule reveal no rings or other surrounding debris, so New Horizons will make a relatively close approach of about 2,200 miles. The spacecraft is aiming for the white X in this image.

New Horizons took its first image of Ultima Thule, from a distance of 107 million miles. The object is easier to see in the image at right, where background stars have been obscured.

After suggestions from the public, the New Horizons team gave 2014 MU69 a nickname: Ultima Thule.

The name’s direct translation is “beyond Thule” and evokes distant places beyond the edges of the known world.

The mythical island of Thule — labeled “TILE” — appears near the Faroe Islands in the Carta Marina, a map of the Nordic world from 1539.

Plymouth Marine Laboratory

New Horizons sets a new record for the farthest images ever taken by a spacecraft. The probe was about 3.79 billion miles from Earth when it photographed the Wishing Well star cluster.

The record was previously held by Voyager 1’s mosaic of the solar system, which includes the famous “Pale Blue Dot” image of Earth.

Voyager 1’s mosaic of the solar system, taken on Valentine’s Day, 1990.

For more about Voyager and the Pale Blue Dot, watch the short documentary below:

After several attempts to observe MU69 crossing in front of a star, the New Horizons team finally observed it briefly blocking the light of a distant, unnamed star.

By comparing the object’s shadow from different telescopes, the team estimated that MU69 is not round. It might be elongated or barbell-shaped, or possibly two objects orbiting each other closely.

Sketch by James Tuttle Keane

MU69 is part of the Kuiper Belt, a wide band of rubble beyond the orbit of Neptune.

An orange dot shows MU69’s location in the Kuiper Belt. Animation by Alex Parker

After years of searching the Kuiper Belt with ground-based telescopes, the New Horizons team turned to the Hubble Space Telescope, which discovered a promising object in 2014.

The Kuiper Belt object formally known as (486958) 2014 MU69.

New Horizons zipped past Pluto and returned images of a surprisingly dynamic and complex world.

Experience a simulated flyby and stand on Pluto in virtual reality: Seeking Pluto’s Frigid Heart.

Before New Horizons, humanity had only fuzzy images of Pluto and its moon Charon, and had little idea of what to expect from the flyby.

Learn more about how New Horizons was poised to change our understanding of the outer solar system in the documentary Fast and Light to Pluto.

Images by NASA, Johns Hopkins Applied Physics Laboratory and Southwest Research Institute, except where noted.