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New Horizons Spacecraft Captures Pluto And Charon's Orbital Dance

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Justine Alford

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953 New Horizons Spacecraft Captures Pluto And Charon's Orbital Dance
Elenarts. Impression of Pluto and its largest moon, Charon.

NASA’s recently awakened New Horizons spacecraft is currently whizzing through our solar system at close to 50,000 kilometers per hour (31,000 mph), having so far covered an immense distance of 5 billion kilometers (3 bn miles) since its launch almost a decade ago. The idea behind this $700 million mission is to finally allow scientists to observe Pluto up close.

Although the steadfast probe isn’t due to flyby until July, it’s already been snapping some grainy portraits of the icy rock to tease us with what’s to come. Now, to whet our scientific appetites once again, NASA has released a time-lapse of the dwarf planet and its largest moon, Charon.


NASA/APL/Southwest Research Institute

This “movie” consists of a compilation of images taken by the craft’s Long Range Reconnaissance Imager (LORRI) over a period of about a week, from January 25th until the 31st. Given that Pluto and Charon both rotate once every 6.4 Earth days, the assembled images allow us to see a whole day on these distant bodies. NASA has also zoomed in four times to make features easier to discern:

NASA/APL/Southwest Research Institute

As you can see, Pluto seems to wobble in space as Charon dances around it, which is due to the satellite’s gravity. Charon is around one-eighth as massive as the dwarf planet, about the size of Texas, making it the largest known moon compared to the size of its host world. These bodies both orbit around a common spot above Pluto’s surface, known as the barycenter, which is where their gravity gets cancelled out; that’s why Pluto looks like it’s wiggling around in space.


If you were expecting a more impressive, less pixelated picture of these icy worlds, bear in mind that New Horizons was more than 200 million kilometers (126 mn miles) away when it captured the first of this series of images. Six and a half days later, the probe had already covered a staggering distance of 8 million kilometers (5 mn miles).

New Horizons is way too distant at the moment to pick up Pluto’s surface features with its imagers, and the shots taken so far had an exposure time of one-tenth of a second, which isn’t enough to make out any of Pluto’s other four much smaller moons. But the point of these early images, which started to come through when New Horizons began its six-month “encounter phase,” is not to gather scientific information, but rather to ensure that the probe is correctly aligned for its historic flyby on July 14. These so called optical navigation surveys allow the New Horizons team to plan a course that ensures the craft isn’t heading on a space debris collision course.

That being said, the portraits are providing us with some useful insight into these distant worlds as well. As New Horizons principal investigator Alan Stern explains in a news release: “… they have the additional benefit of allowing the mission scientists to study the variations in brightness of Pluto and Charon as they rotate, providing a preview of what to expect during the close encounter in July.”

[Via NASA and]


spaceSpace and Physics
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  • solar system,

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  • moon,

  • pluto,

  • dwarf planet,

  • charon,

  • New Horizons,

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