Pluto is not a giant comet!

Within the past week, you may have seen reports of a study that some scientists say indicates Pluto is actually a giant comet that was formed by the aggregation of billions of comets. This is not true! What the study actually found is that both Sputnik Planitia, the left side of Pluto's heart feature, and Comet 67P/Churyumov-Gerasimenko, both were found to have the same isotope of nitrogen on their surfaces. While this is true and suggests they may originate in the same region of the solar system, it does not mean Pluto is a giant comet! In this case, people erroneously drew a conclusion without sufficient data to confirm that conclusion.

Below is a good article by planetary scientist Philip Metzger explaining why Pluto is not a giant comet.

Icy Worlds and Stars with Long Hair - Philip Metzger: Are icy worlds like Pluto just comets because they're made of ice? This post looks at what planets made of and looks at the amazing insides of icy worlds.

Tom Siegfried, former editor of Science News: Pluto's Demotion Ignores Astronomical History

They keep on coming! Here is yet another terrific article about the issue of planet definition and the many problems with the 2006 IAU definition, this time by Tom Siefried, former editor of Science News.

https://www.sciencenews.org/blog/context/pluto-demotion-ignores-astronomical-history?tgt=nr

Siegfried's article refers to a new scientific paper by Philip Metzger, Mark Sykes, Alan Stern, and Kirby Runyon, which can be found at https://arxiv.org/abs/1805.04115.

Guest Blog: Revisiting the definition of a planet - Astronomy Magazine - Interactive Star Charts, Planets, Meteors, Comets, Telescopes

This is my response to Ethan Siegel's May 8 Forbes.com article, "You Won't Like the Consequences of Making Pluto a Planet Again," posted on Astronomy Magazine's blog site.

Guest Blog: Revisiting the definition of a planet - Astronomy Magazine - Interactive Star Charts, Planets, Meteors, Comets, Telescopes

An organically grown planet definition: From Astronomy magazine

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Should you care about Pluto? We asked NASA's Alan Stern and astrobiologist David Grinspoon

Chasing New Horizons: An epic exploration to a strange new world

Chasing New Horizons: An epic exploration to a strange new world

Close to three years after the historic New Horizons Pluto flyby wowed the world, mission principal investigator Alan Stern and astrobiologist and mission science team member David Grinspoon tell the riveting story of a monumental exploration 26 years in the making in their new book Chasing New Horizons: Inside the Epic First Mission to Pluto.

Much like a novel, the book starts with a crisis, the loss of contact with the spacecraft just ten days before the flyby, then goes back to the beginning of everything and narrates the story chronologically, from Stern’s birth through the first thoughts of a Pluto mission just as Voyager 2 visited Neptune in 1989, and the many twists and turns, setbacks and victories that culminated in the triumphant 2015 Pluto flyby.

Stern and Grinspoon are scientists, yet this book is first and foremost a narrative, one that takes readers along on a multi-decade effort that started as a vision by young scientists whose efforts were stymied by a powerful and often set-in-its ways establishment.

From the initial “Pluto Underground” visionaries to the steadfast team members who overcame what seemed like never-ending challenges, readers are familiarized with the many resourceful, persistent characters who made the mission happen, to the point that it feels like we know them personally and are there with them during the journey.

At times, Stern and Grinspoon make references to popular science fiction such as Star Wars and Star Trek, an interesting choice given that Chasing New Horizons often reads and feels like a Star Trek movie. Like chief engineer Scotty, the mission team always manages to find a way to work within what seem to be impossible limitations in terms of time and budget.

One problem is successfully dealt with only to lead to another. If just one of many cancellations or crises or decisions had gone a different way, there would have been no Pluto mission at all, the writers note while recounting each of the do-or-die moments.

Much like the discovery of Pluto itself by Clyde Tombaugh, the story of New Horizons is a tale of persistence. When he arrived at Lowell Observatory in 1929, Tombaugh was told by a professional astronomer that he was “wasting his time” searching for an undiscovered planet. In 2000, after Stern’s team had worked on a mission proposal for 18 months, NASA Associate Administrator for science Ed Weiler canceled the entire Pluto project, declaring it “dead, dead, dead.”

But the “Pluto Underground” refused to accept a death sentence. Humorously, the writers titled the chapter immediately following this declaration, “The Undead.”

In total, proposed Pluto missions were canceled five times. If not for the incredible persistence of those committed to making one happen, the world today would still know little about this mysterious world.

“We really need an orbiter that can map 100 percent of everything in the Pluto system. We want to bring radar to look down to the ice; we want to bring mass spectrometers to sample the atmosphere; we want thermal mappers,” Stern told Spaceflight Insider, New Horizons raised so many questions about Pluto and its moons that Pluto scientists are already laying the groundwork for a Pluto orbiter.

By raising the strong possibility that Pluto has a subsurface ocean, the mission has put Pluto on the radar screen of scientists who study ocean worlds and want to visit a broad sample of these worlds, Stern noted.

New Horizons was about more than science; it was about the motivation to explore a “strange new world,”to “go where no one has gone before.” The motivation to explore kept the dream alive even when everything seemed lost.

When it finally happened, the flyby was as much about aesthetics and beauty as it was about science, Stern and Grinspoon note. With its diverse surface features and iconic heart-shaped region named for Clyde Tombaugh, Pluto turned out to be a beautiful, breathtaking world.

Recounting an especially poignant moment in the epilogue “Coda: A Final Discovery,” Stern and Grinspoon recount New Horizons’ unanticipated human impact as a new generation’s Apollo experience with a moving story about how the flyby inspired a Florida teenager to go from failing school to being an A student upon deciding he wanted a career in space exploration.

“The book is really an adventure story about how a bunch of young scientists who were determined managed to overcome the system and make the farthest exploration in the history of human exploration. And it’s a story about how you build space missions and plan flybys and also about the science,” Stern said. “It’s three stories woven together.”

"Yes, Pluto is a Planet"--Terrific Washington Post Article by Alan Stern and David Grinspoon

This Washington Post article by Alan Stern and David Grinspoon does a great job in presenting the case for Pluto's planet status. This is a must read for Pluto supporters and advocates of the geophysical planet definition.

https://www.washingtonpost.com/news/speaking-of-science/wp/2018/05/07/yes-pluto-is-a-planet/?commentId=9d9f6b96-e408-4be7-894a-409ae4821e8c&utm_term=.1da648439ae8