Tag Archives: Alan Stern

Mars madness and more this week

Mars Madness continues this week at the Museum of Flight, and a couple of astronomy clubs have interesting events on the calendar as well.

Mars Madness

Myers

Roger Myers. Photo: Museum of Flight

Lots of things go mad during the month of March, and the Museum of Flight is looking at Mars with special programs each Saturday. This Saturday, March 11 at 2 p.m. Roger Myers, formerly of Aerojet Rocketdyne, will give a talk about getting to Mars and back. Myers should know; he has worked on space transportation and in-space propulsion for more than 30 years, on dozens of missions including all Mars landings after Viking. He is a Fellow of the AIAA, a member of the Washington State Academy of Sciences, is the president of the Electric Rocket Propulsion Society, and was awarded the AIAA Wyld Propulsion Award in 2014.

If you’re headed out to the museum on Saturday, don’t miss the weekly aerospace update at 1 p.m.

Tacoma Astronomical Society

The Tacoma Astronomical Society will hold its monthly meeting at 7:30 p.m. Tuesday, March 7 in room 175 of Thompson Hall on the campus of the University of Puget Sound. TAS member Dave Armstrong will discuss his approach to telescope mirror fabrication.

BEAS and Pluto

The Boeing Employees Astronomical Society will meet at 6:30 p.m. Thursday, March 9 at the Boeing “Oxbow” Fitness Center. Participants will view a webinar presentation about the Pluto New Horizons mission from the mission’s principal investigator, Alan Stern. Guests are welcome but must RSVP here.

Battle Point Astronomical Association

BP Astro KidsThe Battle Point Astronomical Association has a full evening of events planned for Saturday, March 11. Its popular BP Astro Kids program will meet at 4 p.m. and 5 p.m. The family date night for this month will be a look at how the Hubble Space Telescope gets all of its gorgeous photos back to Earth. Participants will transmit their own images to each other, paint universe photos and more. Suggested donation is $5 to cover supplies.

BPAAAt 7:30 p.m. the club’s planetarium show will be “Climbing the Cosmic Distance Ladder.” Astronomer Steve Ruhl will show how astronomers, past and present, determine distances to objects. If the sky is clear, club members will be on hand with telescopes. It’s free for BPAA members, $2 donation suggested for non-members, and $5 for families.

It all happens at the association’s Edwin Ritchie Observatory in Battle Point Park on Bainbridge Island.

Futures file

You can scout out future astronomy events on our calendar. We’ve recently added BP Astro Kids events for the spring and summer and the meetings of the Boeing Employees Astronomical Society for the next several months.

Up in the sky

Jupiter is well placed for viewing after midnight this week as it approaches opposition on April 7. This Week’s Sky at a Glance from Sky & Telescope magazine and The Sky This Week from Astronomy offer more observing highlights for the week.

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Kelly Beatty’s history of Pluto

The history of Pluto goes way back before it became a tiny twinkle in Clyde Tombaugh’s blink comparator. Kelly Beatty, a senior editor at Sky & Telescope magazine, told the story of Pluto in his keynote address Saturday at the annual banquet of the Seattle Astronomical Society.

Scheiderer and Beatty

Kelly Beatty, right, with Seattle Astronomy’s Greg Scheiderer at the annual banquet of the Seattle Astronomical Society January 28, 2017. Astronomy guys love their astronomy ties. Photo: Greg Scheiderer.

In a way, according to Beatty, the hunt for Pluto dates back to the late 1700s. The Titius–Bode law (since repealed) of the distances to the planets from the Sun worked well, with one exception: according to the law, there should be a planet between Mars and Jupiter. Thus a group of astronomers calling themselves the “celestial police,” led by Franz Xaver von Zach, set out to find this elusive object. They did it; on New Year’s Day, 1801, Giuseppe Piazzi discovered Ceres. It wasn’t long before Juno, Vesta, and Pallas we found. At first all four were labeled planets, but now they’re known as the four largest asteroids—and possibly the first celestial objects to be demoted in status.

Dumb, fool luck

Lowell blink comparator

Blink comparator used by Clyde Tombaugh at Lowell Observatory to discover Pluto. Photo: © User:Pretzelpaws / Wikimedia Commons / CC-BY-SA-3.0.

Later, because of irregularities in the motion of Uranus, astronomers predicted another planet out beyond its orbit. But even after the discovery of Neptune in 1846, anomalies remained. Percival Lowell and William Pickering predicted there was yet another planet beyond Neptune. The hunt was on for Planet X, and Pluto was finally discovered by Clyde Tombaugh in 1930. We soon learned that Pluto was pretty small, which lent some irony to its discovery.

“Pluto didn’t have any effect on Uranus and Neptune at all,” Beatty said. “It turns out that the mathematics were incorrect, the positional accuracy of those early observations was bad. There was no basis to the prediction whatsoever, and by dumb, fool luck Clyde found the planet Pluto that he had been seeking within about six degrees of the predicted position. Freakingly by accident.”

We didn’t know a whole lot about Pluto for a long time. The best photos we could get were fuzzy Hubble Space Telescope shots. Astronomers found methane ice on Pluto in 1976, and its moon Charon was discovered in 1978. Pluto’s atmosphere was discovered in 1988 when it occulted a star.

Pluto on thin ice

“In 1998 the bottom fell out of the pro-Pluto movement,” Beatty said. The beginning of the end was the discovery of another distant object in what we now call the Kuiper Belt. Astronomers figured that there had to be more out there than just Pluto, and we now know of more than 1,800 of them. Many of these objects are locked in a 3:2 orbital resonance with Neptune, just like Pluto.

“Not only is Pluto not alone, it’s not even unique in its orbit,” Beatty said. “Things did not look good for Pluto and its planet status.”

The International Astronomical Union (IAU) started hearing chatter that Pluto should not be a planet, and in 1999 it passed a resolution declaring that it still was. Brian Marsden, who headed the minor planet center of IAU, really wanted to classify Pluto as an asteroid, according to Beatty.

Then, in 2005, Eris was discovered. At the time it appeared to be bigger than Pluto, though we now know it is slightly smaller. It was bureaucracy that finally knocked Pluto off the planet list. Different committees at the IAU name planets and asteroids, so to decide to which committee to refer the new discovery for naming, they had to decide what it was. This led to the new definition of planet, under which neither Eris nor Pluto fall. The IAU declared Pluto to be a dwarf planet in 2006.

Beatty is not fond of the IAU definition of planet: an object that orbits the Sun, has enough mass to be round, and has “cleared the neighborhood of its orbit.”

“It’s a really stupid definition,” Beatty said, mostly because it’s hard to know the mass of faraway objects, and so the definition is difficult to apply. Plus he finds it puzzling that a dwarf planet is not a planet.

“We have dwarf stars which are considered stars.” he pointed out. “We have dwarf galaxies that are considered galaxies. A chihuahua is still a dog.”

New Horizons

Pluto

New Horizons close-up of Pluto, one of the first and most iconic images from the mission. Photo: NASA.

Planet or not, the New Horizons flyby of Pluto in 2015 gave us a ton of new information about it and its moons. Beatty shared numerous photos of and findings about Pluto from the mission. It’s mostly made of rock, and might have liquid water below its surface. The surface features are mostly hard-frozen water ice, with a little frozen nitrogen, methane, and carbon dioxide mixed in.

Most fascinating is evidence of geology happening right now in the form of flowing nitrogen ice.

“Pluto’s surface, against all odds, out in the frozen corner of the solar system,” Beatty marveled, “has flowing glaciers on it.”

The last of the Pluto data from New Horizons arrived on Earth back in October, but the mission isn’t over. The probe is headed out for a look at the Kuiper Belt object 2014 MU69, at which it will arrive on January 1, 2019.

Beatty said this great new data about Pluto was worth the wait.

“We finally know what this planet/dwarf planet/interesting world looks like,” he said. “It was a 30-year effort from the time the Pluto missions were first conceived until we finally got out there. Some of the people involved, like Alan Stern, were there every year of the way, and boy, what a rich reward they have for their efforts.”

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