| Nearly 4 billion miles from Earth, where the sun looks like just another star, and space is scattered with frozen fragments left over from the birth of distant planets, NASA's New Horizons spacecraft just caught a glimpse of the unknown. | Left: A composite image of the Kuiper Belt object Ultima Thule (indicated by yellow crosshairs) produced from dozens of exposures taken by the New Horizons spacecraft. Right: A magnified view of the region in the yellow box, produced by subtracting the background of stars from the image. (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute) | These images, captured by New Horizons's Long Range Reconnaissance Imager, show a small, peanut-shaped inhabitant of the Kuiper Belt known as Ultima Thule. | | New Horizons is scheduled for a close encounter with the far-flung space rock just after midnight on New Year's Day, 2019. | | The moniker "Utima Thule," which was bestowed by NASA after a naming contest earlier this year, comes from an ancient expression for the distant north. | | | But in literature, the term has a metaphorical meaning, summoning up a place beyond the borders of the known world, as the Roman writer Virgil put it, where the sun rarely sets, and humankind's greatest ambitions are waiting to be grasped. | | The idea persisted, captivating writers across continents and throughout the centuries. Henry Wadsworth Longfellow dedicated an entire book of poetry to the subject, writing of a "land of dreams ... of fiction and of truth, the Lost Atlantis of our youth." | | "A wild weird clime that lieth, sublime," Edgar Allan Poe described it, "out of space . . . out of time!" | | For now, the real life Ultima Thule is almost as mysterious as the mythological version. It is so distant and small that none but the most powerful telescopes can see it, and even then they only get a vague sense of its faint, fuzzy form. | | Scientists weren't sure about its size or shape until they spotted it passing in front of another star last summer; by measuring the object's shadow, they determined it is likely composed of two bodies roughly the size of Manhattan orbiting one another. Alan Stern, the New Horizons mission's principal investigator, wrote that Ultima Thule is probably a "primodial relic" of the planet forming processes that produced the Kuiper Belt's bigger bodies, like Pluto, Sedna and Eris. | | | New Horizons's Jan. 1, 2019 flyby will take it within 2,200 miles of Ultima Thule, making it the most distant body ever explored by humans. During that encounter, the spacecraft's instruments will measure the object's mass and attempt to discern its composition. | | Then, scientists hope, Ultima Thule will no longer be a mystery. New Horizons will have expanded the borders of the known world. | | | | | |
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