New Horizons’ next target caught making a star blink

Knowing object’s specs will help plan Pluto spacecraft’s 2019 flyby of MU69

telescope in Argentina

LYING IN WAIT  The New Horizons team spread 24 of these small telescopes around southern Argentina to catch a cosmic coincidence.


With Pluto in its rearview mirror, the New Horizons spacecraft is zipping towards a more far-out object. But it’s not flying blind. Using ground-based telescopes, the New Horizons team has spotted its next destination eclipsing a distant star. The event will reveal the rock’s specs in advance of the spacecraft’s visit in a year and a half.

The object, called 2014 MU69, lives in the Kuiper Belt more than 6.5 billion kilometers from Earth. Members of the New Horizons team calculated that they would be able to see its shadow from the southern tip of Argentina just past midnight local time on July 17 as MU69 eclipsed (or occulted) a star.

So the team deployed a fleet of 24 16-inch-wide telescopes across the region to make sure the object didn’t slip past unseen.

winking star gif
A WINK AND A NOD A fleet of small telescopes in rural Argentina watched a star wink out (center) as an object billions of kilometers away blocked its light on July 17. The Pluto-passing New Horizons spacecraft will visit that object New Year’s Day, 2019. SwRI/JHUAPL/NASA

“At least five of them caught the shadow — which is more than I expected!” said team member Alex Parker of the Southwest Research Institute in Boulder, Colo., on Twitter. This is the fifth time the team has seen MU69 eclipse a star, and the first from this remote site.

New Horizons visited Pluto in 2015 and will fly by MU69 on January 1, 2019. The space rock will be the most distant solar system object ever visited. Details of the occultation will reveal MU69’s size, shape, orbit and environment, helping the team plan its observations.

“This effort…was the most challenging stellar occultation in the history of astronomy, but we did it!” said New Horizons principal investigator Alan Stern in a statement.

Lisa Grossman is the astronomy writer. She has a degree in astronomy from Cornell University and a graduate certificate in science writing from University of California, Santa Cruz. She lives near Boston.

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