More than 200 people turned out to hear the latest discoveries about Pluto from University of Delaware professor Harry Shipman.

A 'cosmic crush' on Pluto

New insights revealed about beloved planet during Vernon Lecture

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12:38 p.m., May 2, 2016--Pluto has been one of the public’s favorite planets ever since Venetia Burney, an 11-year-old English schoolgirl, suggested the name after the icy orb was discovered in 1930. Later that year, Walt Disney created a cartoon dog with the same name. 

“That may be why we’re so in love with Pluto,” University of Delaware astronomer Harry Shipman told an audience of more than 200 as he began the Harcourt C. (Ace) Vernon Lecture at UD’s Clayton Hall Conference Center on Tuesday, April 26. 

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One thing is for sure: the spectacular photos of Pluto taken last July by NASA’s New Horizons spacecraft have heaven watchers of all ages stoked. 

Shipman, the Annie Jump Cannon Chair of Physics and Astronomy at UD, where he has taught and done research for the past 42 years, presented some of New Horizons’ latest findings and said he anticipates many more discoveries since only about half the spacecraft’s pictures of Pluto have reached Earth so far, arriving here at a rate of about one bit per second. 

The mission’s first images instantly transformed that previous best photo of Pluto taken by the Hubble Telescope — a fuzzy dot — into a world like no other seen before. 

“We thought geologically it would be very old and cooling down,” Shipman said.

But instead of a planet pocked with lots of craters, an almost smooth icy surface shone forth in one major region, which scientists estimate to be less than 10 million years old and could still be geologically active. 

This great ice plain, one of Pluto’s most striking features, is informally named “Sputnik Planum” and occupies a huge basin the size of Hudson Bay. It is covered in layers of ice, starting at the surface with frozen methane, which floats on frozen water, which floats on frozen nitrogen, which floats on frozen carbon dioxide.

“There’s an enormous amount of different types of terrain here,” Shipman said, presenting a NASA graphic with more than a dozen different colors representing Pluto’s various topographies. 

There’s the dark, elongated region along Pluto’s equator nicknamed “The Whale,” which scientists speculate gets its dark reddish-brown color from tholins, formed from irradiated methane.

Nestled in a mountain range just north of Sputnik Planum, a frozen former lake of liquid nitrogen provides tantalizing evidence that millions to billions of years ago, Pluto had much warmer conditions and a much higher-pressure atmosphere.

Another unexpected finding: Pluto still has an atmosphere, albeit a very thin one. It’s made of mostly methane and hydrogen, seen in photos as a blue haze. Scientists thought this atmosphere would have frozen and collapsed by now as Pluto, on its elliptical orbit, moves farther away from the sun. It’s just another mystery to explore in this bizarre new world.

As far as the names of the features on Pluto and its moons go, Shipman said they are unofficial until the International Astronomical Union approves them. “Tombaugh Regio,” where Pluto’s “heart” is found, is named for the late Clyde Tombaugh, the American astronomer who discovered Pluto. Some of Tombaugh’s ashes are on board the New Horizons spacecraft. And “Skywalker Crater” on Charon, Pluto’s giant moon, is named after Luke Skywalker in Star Wars, of course.

Pluto also has four smaller moons, but they don’t behave like most. While Earth’s moon does a complete rotation on its axis every 27 days, these moons — Styx, Nix, Kerberos and Hydra — “are spinning like crazy,” Shipman said. 

At a dinner earlier that evening, Shipman said three people at his table could remember when Russia launched Sputnik, the world’s first artificial satellite, into space in 1957, triggering the Space Race. 

“And here we are now with New Horizons 3 billion miles from Earth — amazing,” Shipman said. 

It’s the farthest ever flown to an object in our solar system, Shipman said, although the two Voyager space probes, launched in 1977, have logged many, many more miles on their journey into interstellar space and continue to send data back to Earth. As a principal investigator on the Voyager mission, UD professor emeritus Norman Ness designed the magnetometers that enable the spacecraft to measure magnetic fields from planets, moons and now space plasma and dust beyond the solar system.

Thanks to a gravity assist from Jupiter, New Horizons got punted like a kickball toward Pluto, which Shipman demonstrated on stage. Thanks to this booster, it took New Horizons only about 10 years to reach Pluto. If the spacecraft had been sent on a standard trajectory, it would have taken 125 years to get there. 

What’s up next for New Horizons? A formal proposal for the mission’s next phase was submitted to NASA less than two weeks ago. It includes a close encounter with MU69, a Kuiper Belt object, on Jan. 1, 2019. 

“No New Year’s party for the Pluto crew,” Shipman said, adding that the mission will also look at about 20 of Pluto’s thousands of icy co-inhabitants of the Kuiper Belt, the doughnut-shaped ring around the sun. 

“The Kuiper Belt is where all the action is. It’s probably where all the comets come from. So we’re going to learn a lot about this stuff that’s out there,” Shipman said.  

Shipman then spoke of a visit to the Wright brothers’ airfield at Kitty Hawk, North Carolina, where they made the first successful human flight. 

“Humans first escaped Earth’s gravity in 1903,” Shipman said. “And here we are going to the edge of the solar system. It’s a remarkable human adventure.” 

Article by Tracey Bryant

Photos of lecture by Lane McLaughlin

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