How Big Is Pluto?

By Andrej Mrevlje |

I was up early on July 10, reading an interesting but disheartening follow-up story on the Greek crisis and the irrational behavior of Germany and the European Union. Before the important meeting of EU leaders in Brussels, very few countries had expressed solidarity with Greece, hoping that all the Union planets would get back into regular orbit. The big and strong players in Brussels were oriented towards squeezing whatever they could out of Greece and then kicking it out of the European solar system. It was at that instant that the news came from space. It was unusually early in the day for this kind of news, but you could tell that NASA’s people were waiting for it nervously: New Horizon, a probe that left the Earth nine years ago, had sent us a beautiful photo of Pluto and its little moon, Charon. NASA said the photo was taken four hours earlier and “only” 3.7 million miles from this far-away dwarf planet, not yet seen or visited by humans in our solar system. I cannot imagine how close 3.7 million miles (5.92 million kilometers) would be for a probe looking at a planet like Pluto, or how far the 2.9 billion miles (4.64 billion kilometers, the distance from the Earth to Pluto) are for it to travel. Even nine years of travelling at 56.536 km/h is something an adventurous person like myself can hardly perceive as a practical idea. But here it was, a lovely couple from the edge of our solar system!

I dropped the news of Greece and set my mind on Pluto. I first read about this fantastical news in a Business Insider piece by Jessica Orwig. I liked the tone of the piece as Orwig described the voyage of New Horizon as one might describe the old Orient Express train with fashionable European aristocracy on board, travelling and observing the unknown and fierce landscape through the windows of the car restaurant while sipping a good French wine. There are no passengers on a 500-kilo probe. New Horizon has been directed and commanded from a distant Earth, and was launched in 2006 because the only photo captured with the otherwise powerful Hubble Telescope in 1994 was incredibly fuzzy due to the planet’s small size.

The actual search for “Planet X,” as it was originally called, started in the early 1900s. There are some early NASA reports about evidence that this small planet existed in 1909 and 1915, but it was officially discovered in 1930 after painstaking research of Clyde Tombaugh, a 24-year-old American astrologer. Pluto, which has only 0.02 percent of Earth’s mass, got the name from 11-year old girl with a passion for the Greek mythology. Venetia Phair, who died in 2009, the only child who was able to name her own planet, could not see the face of her planet the way we see it now. Neither could the man who discovered Pluto; Clyde Tombaugh died in 1997 at the age of 90, but a portion of his ashes were placed aboard New Horizons for its trip to Pluto.

As NASA prepared for the launch of the ambitious project, the academic debate over the importance of the odd little cosmic body heated up. Just a few months after  New Horizon was sent into deep space, the International Astronomical Union (IAU) accepted a resolution regarding Pluto. And while New Horizon was created by scientists hoping to get facts and answers about the mysterious little planet, the IAU bureaucrats decided Pluto does not belong to the family of planets in our solar system. Only Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune qualify to be members of the family, while Pluto has been downgraded  to a dwarf planet and sent from home like Hansel and Gretel being cast out of their too-small house to wander the woods. Why? Because members of IAU agreed that a “planet” is defined as a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.

Luckily, the gentlemen of IAU came up with this decision too late – that is, after the departure of the probe. Who knows if their decision would have turned off the government and other donors who financed the project, regardless of how cheap it seems compared to many projects intended to merely entertain or, worse, annihilate human civilization, as described in this Vox’s article. However, the scientists and engineers who want to see the face of Pluto and try to at least understand how it is possible for such a small, light planet to keep a moon in its orbit and have its own atmosphere, continue to fight for its status as a planet.

Alan Stern, the head of the New Horizons mission, declared at the time, “I’m embarrassed for astronomy.” He called the decision a “farce,” arguing that the definition of a planet wasn’t accurate and that the area around the orbit of other planets is also not “cleared.”. In 2008, NASA sponsored a conference called “The Great Planet Debate.” The intent was to find consensus on the definition of planet, and hence on Pluto’s status. The participants did not reach an accord, settling instead on the definition of Pluto and similar planets as “plutoids.”

However, four days after the first clear portrait of Pluto and his moon, New Horizon rang again. This time the probe was already some millions of kilometers away from Pluto. While approaching the planet, New Horizon was using all its equipment to scan, photograph and analyze the planet and did not communicate with the base. On Tuesday, July 14, the photos arrived and created a wave of enthusiasm on the continent where, just a few hours before, Germany probably created conditions for the dismantlement of the European Union with its sanctions against Greece. But who can blame people for taking a break to celebrate? In many ways, the event shook our planet. As Michael Byrne wrote for Motherboard:

Tonight, we were waiting for a signal—a bit stream. After nine years of travel, the New Horizons spacecraft passed Pluto early Tuesday morning, breaking off communication with Earth as it turned its antennas toward the dwarf planet 12,500 km below. As the craft made its silent flyby, NASA engineers had all day to worry and wait for its scheduled reconnection. That came at 8:54 PM EST, just a few minutes ahead of schedule. A cheer went up at mission control and, one by one, the different engineering teams called in, reporting the ship’s status:

“We’ve reported the expected amount of data.”

“All hardware is healthy.”

“Propulsion system is nominal.”

“Nominal for power.”

“All temperatures green.”

And, finally: “We are outbound from Pluto.”

It will be many months before the craft has transmitted all of its Pluto data back to Earth, but we can take an exhilarated breath knowing that it’s on the way.

The whole thing was breathtaking and absolutely overwhelming. We got the images, but not enough data to understand what we are seeing. It will take the next 16 months to get all the data New Horizon collected during its flyby of Pluto. While we waited for NASA to tell us what they were learning, some of the media went insane trying to stay on top of the news. They could not cope with how little we know about what is happening at the edge of our solar system. In some ways, this Pluto event shows how desperate for constant, new information our news system has gotten with the streaming culture that came with cable TV and the digitalization of the media. Buzzfeed and Mashable’s so-called reports on the new image of Pluto are trying and tasteless. They are an attempt to distract from real news – something which should be in the interest of all of humanity. Thankfully it was no more than 24 hours until New Horizon moved further into the universe and, while waiting new instructions from the base, started to unload the data it collected while flying in the vicinity of Pluto. For readers who want to know what is happening at the extreme edge of our solar neighborhood, here are some links for further reading:

Business Insider, which has done pretty complete reporting on this historical event, published an article describing how Pluto is more than just a dead, frozen piece of rock and is, in fact, still geologically active – something that gives scientists hope to discover new, extraordinary things about the universe. It actually explains some of the new discoveries that scientists have made about this planet. The Daily Beast has a good piece about what is next for New Horizon after it paid a historic visit to Pluto. And then the most recent data about Pluto’s so-called “tail,” which may be able to provide an explanation for the atmosphere of this very important cosmic body. Last but not least, a member of the New Horizon team wrote a lovely piece that gives an inside look into a story of passion and perseverance.

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