Winter Solstice: "From out the womb of night is birthed the Infant Light"

 

“Dark ruled the Earth, and death has reigned,

But on the Wheel does spin!

From out the womb of night

Is birthed the Infant Light!

The Sun has come again! The Sun has come again!

The Sun, the Sun, has come again!”

 ~from “Solstice Joy to the World”

 The year 2020 has in some ways gotten a bad rap. Yes, it was unlike anything anyone expected last New Year’s, and it brought with it pain, suffering, and loss on a global level.

 But in a very real sense, the global pandemic, the many powerful hurricanes, and the resulting economic tragedies cannot be blamed on the year. To one extent or another, all of these are rooted at least somewhat in long-term destructive human activity such as habitat destruction; 150 years of greenhouse gas emissions; and treating nature as something to plunder and hoard rather than a living web of which we all are a part. To paraphrase Shakespeare, the fault is not in our year, but in ourselves.

Yet at this time of year, which so many view as sacred, we can see hope. Many cultures have for thousands of years viewed the Winter Solstice as the symbolic rebirth of the Sun after a long period of darkness. This year, we need that hope more than ever.

Ten years ago, on the Winter Solstice, some parts of the world were treated to a stunning total lunar eclipse. This year, we have a rare conjunction of the solar system’s two biggest planets, Jupiter and Saturn, on Solstice night. The two planets have been moving closer together in the sky for quite a while, and tonight, they reach their closest point to one another in the western evening twilight.

Everyone has had to make adjustments this year. Among those adjustments has been a turn to astronomy as a source of comfort. Many people have reported in social media and on blogs that astronomical observation, reading about astronomy, or watching programs about it have served as calming, comforting influences during the most difficult periods of their lives.

Finding comfort and joy in astronomy and in nature are good things. Recognizing that we need to find a different way to live, a way to be in harmony with nature, is necessary for our survival, given that we are running out of time to address catastrophic climate change and its many adverse effects, including pandemics.

This season has long been viewed as a time of miracles, magic, and wishes coming true, a time when anything can happen. I believe that primal joy is directly related to the return of the light. The moment when the advance of darkness is halted, when darkness and death give way to light and life, even if the latter are now only an unseen promise, is at its core about hope.

We now have the hope of two vaccines, which will be distributed worldwide in the months ahead. And we have the knowledge that we can do things such as reduce our carbon footprints and the amount of pollution we generate—as happened during the lockdowns—to avoid further environmental catastrophe.

In the space community, we have seen the US return, after nine years, to launching astronauts on American vehicles from American soil to the International Space Station. We have seen more countries decide to return to the Moon, whether robotically or by returning people there. The Star Trek world of a brighter future is still possible.

None of this will be easy. But in the words of writer Madeleine L’Engle, “Now we leave our tears for mirth. Now, we sing, not death, but birth.” As darkness gives way to light, on this shortest day and longest night, hope is born anew, for all people, and for all who call this planet home.

 

Planetary Scientist Alan Stern Heading to Space on Virgin Galactic Space...

White mountain peaks on Pluto not caused by snow

White mountain peaks on Pluto not caused by snow

What Really Makes A Planet? Lessons Not Learned 14 Years after Pluto's Demotion

Ethan Siegel’s September 2, 2020, Forbes article, “What Makes a Planet: Lessons Learned 14 Years after Pluto’s Demotion” ironically indicates the writer has not learned any lessons from a decade and a half of controversy and is simply doubling down on his insistence that Pluto isn’t a planet, in spite of scientific discoveries over the last decade and a half.

The primary problem with Siegel’s article is its near-complete denial of the continuing planet debate, blind repetition of the controversial IAU position, and complete failure to acknowledge legitimate scientific opposition to that position.

Siegel, an astrophysicist rather than a planetary scientist, misrepresents and minimizes the community of planetary scientists who reject the IAU definition in favor of a geophysical one with his statement, “Pluto doesn’t come close to meeting the third criteria, and so only those who go by geophysical definitions — where location and formation history are ignored — still consider Pluto a planet in any way.”

That last sentence is nothing less than denigration of the many planetary scientists who prefer the geophysical definition with the false claim that they “ignore” location and formation history.

Siegel’s assumed premise, that there are only three classes of planets—terrestrials, ice giants, and gas giants, is false. This is the central weakness of his article. He assumes there are only three types of planets because either he or the IAU or both say so, without providing any supporting evidence for that claim.

The reality is there are additional classes of planets, starting with the dwarf planets. This term was initially coined by Alan Stern in 1991 to designate a new class of planets in addition to terrestrials, gas giants, and ice giants. When four percent of the IAU adopted their controversial planet definition requiring an object to “clear its orbit” to be a planet, they misused Stern’s term by stating dwarf planets are not planets at all but another type of object entirely.

This claim is not borne out in New Horizons’ findings at Pluto or in Dawn’s findings at Ceres. Both worlds are rounded by their own gravity and geologically differentiated into core, mantle, and crust. Both have complex planetary processes and probably belong in what should be yet another new planet category, the ocean worlds—worlds with subsurface oceans that could potentially harbor microbial life.

In addition to his failure to disclose that orbit clearing was adopted by just four percent of the IAU, most of whom were not planetary scientists but other types of astronomers, Siegel also ignores the fact that the claim dwarf planets are not planets at all was the decision of 333 individuals in a room on the last day of a two week conference rather than some type of objective truth.

Beyond repeating the claim that orbit clearing is a requirement for planethood, for no reason other than the IAU dictated it, Siegel cherry picks classes of objects he refers to as planets in spite of the fact that they do not meet the IAU definition he so steadfastly supports. He seems to accept the idea that rogue planets can be planets in spite of the fact that they do not orbit the Sun or clear their orbits (they have no orbits to clear). He also seems to have no problem referring to exoplanets as planets, in spite of the fact that they do not meet the first IAU requirement, which is that a planet must orbit the Sun as opposed to any star.

Most of Siegel’s claims seem to be concocted by him, with no evidence to back them up. For example, he refers to super-Earths as an “artificial class” without justifying why he considers this class “artificial.” Analyses of exoplanet discoveries made by the Kepler and TESS missions indicate super-Earth planets with sizes between that of Earth and Neptune do, in fact, exist. We still know little about them, including their percentages of rock versus gas, yet their existence has never been disproven.

As to the question of why our solar system does not have a super-Earth planet, that is still a mystery. Scientists have observed a wide variety of exoplanet systems, including some with multiple stars and some with several giant planets all orbiting in different planes. They have discovered “puffy” planets, water planets, hot Jupiters falling into their stars, and a wide variety of solar system structures that suggest there very likely is more than one way for a planetary system to form.

Significantly, we have not yet found dwarf exoplanets, but that is likely because they are too small to find with current technology. This will almost certainly change soon. When exo-dwarf planets are found, will Siegel still hold to his claim that the range of planet sizes is limited to “smaller than Mars and Mercury to larger than the size of Jupiter?”

More problematic is Siegel’s claim that Pluto somehow has a different formation history than the larger solar system planets. This is pure conjecture. According to a recent study cited by planetary scientist Phil Metzger, protoplanets in early solar systems eventually grow large enough that their gravity stirs the area around them, slowing their rotation rates until they accrete all the material within their orbital zones. When they reach this stage, these protoplanets become full planets or “oligarchs,” the largest objects in those orbits. At this point, there are no other phases of planetary growth they fail to reach.

Nearby giant planets can keep other planets in their systems small by gobbling up material from their orbits. Migration of giant planets in early stellar systems can also do this. Both Mars and Pluto likely remained small because the nearby giant planets accreted material from their orbits before they could. But other than size, there is nothing inherently different between Mars and Pluto. Mars has a smaller orbit to “clear” because it is closer to the Sun. The only reason Pluto cannot clear its orbit is the fact that it is further from the Sun and therefore has a larger orbit to clear.

Interestingly, calculations by planetary scientists confirm that if Earth were in Pluto’s orbit, it would not clear that orbit either. This reveals a serious flaw in the IAU definition—that the same object can be a planet in one location and not a planet in another location.

Siegel and the IAU argue that Mars and Pluto are completely separate categories of objects, yet both formed via the same processes. The only difference is the amount of material that was near their orbits after they finished growing. This is not a legitimate reason for putting these objects in two separate categories.

Calculations by Metzger indicate that the hypothetical large planet in the outer solar system, Planet X, would not clear its orbit even under the formula cited by Jean Luc Margot and quoted in Siegel’s article, when it approaches its closest position to the Sun, known as perihelion.

Furthermore, Margot’s formula is flawed because planets can be in positions where they clear their orbits only to be subsequently interact with other planets in their systems and be ejected into much more distant orbits they cannot clear.

Contrary to Siegel’s statement, the geophysical definition does not ignore an object’s location. It simply does not make location a deciding factor for planethood. By recognizing the non-dominance of the planetary subclass known as dwarf planets, it acknowledges their location and dynamics while still classing them as planets.

Meanwhile, Siegel and the IAU completely ignore dwarf planets’ intrinsic properties, which are the same as those of the larger, rocky planets. Pluto is 70 percent rock, and Eris, being more massive, likely has a higher rock content. In describing New Horizons’ findings at Pluto, Siegel ironically reads off a list of planetary characteristics—an atmosphere with hazes, ice mountains and plains that float on top of a liquid ocean, snowy weather patterns, and varied surfaces that change over time, but then goes on to discount all of these in terms of making Pluto a planet.

At the same time, Siegel has no problem lumping dwarf planets together with asteroids and comets, which are very different objects, the latter not large enough to be rounded by their own gravity, solely due to their locations. He says Pluto fits in much better with the Kuiper Belt Objects while ignoring the fact that there are two very different types of KBOs—one type large enough to be spherical and the other not. The latter are loosely held together piles of ice and rock, as opposed to the complex dwarf planets.

Siegel says regarding Pluto, “In many ways, it’s more complex and has more potential for interesting chemical reactions — possibly even including biological activity — than bona fide planets such as Mercury.”

In other words, Pluto has a multitude of planetary processes and features but isn’t a planet because the IAU says so??? How does any of this make sense? 

The fact is, the IAU’s so-called “third criterion,” that an object must clear its orbit to be a planet, was concocted for the sole, non-scientific reason of keeping the number of solar system planets small and excluding Pluto.

In summary, Siegel’s claims that our solar system has only eight planets and that from the perspective of astronomers, Pluto was never a planet at all is nothing more than an appeal to authority—which is exactly the opposite of the scientific method!

Most astronomers do not study planets. Should planetary scientists tell those who study black holes what a black hole is and is not? Asking astronomers who study completely different fields to define planet makes no sense. It is akin to asking podiatrists to define brain surgery.

After 14 years, here we are—at the same place we were in 2006 but with a lot more knowledge of Pluto, thanks to New Horizons. The IAU and Siegel cherry pick the data they want and use circular reasoning to make their points. None of that makes dwarf planets, including Pluto, any less than a subclass of full planets.

The Whole Story of Pluto: Responding to Elizabeth Stanway of the University of Warwick

Dr. Elizabeth Stanway’s article, “The Story of Pluto” is highly problematic on several levels, starting with the fact that instead of actually telling the story of Pluto, it tells one side of that story, a story that remains a matter of ongoing debate to this day.

 Notably, Stanway is not a planetary scientist but, according to her web page at the University of Warwick, a specialist in observational cosmology. In spite of this, the University of Warwick had her write an article about Pluto, a subject she does not study. Could they not find a planetary scientist to write this?

Not once in her article does Stanway ever mention the fact that Pluto’s status and the question of how to define the term planet remains a controversy with two legitimate sides. She begins by saying that adults and books more than 10 years old portray the solar system as having nine planets, in contrast with newer books that portray it as having eight. This is already untrue, as many books have been published over the last decade that teach the controversy rather than present one view of it as gospel truth.

She fails to mention that the controversial IAU planet definition was adopted by just four percent of its members, most of whom were not planetary scientists but other types of astronomers, and that their decision was immediately opposed by an equal number of planetary scientists in a formal petition led by New Horizons principal investigator Alan Stern, one of the leading Pluto scholars in the world.

Neither does she acknowledge the alternate geophysical planet definition, which was presented to the Lunar and Planetary Sciences conferences in 2017 and 2018, garnering significant media attention.

Stanway goes on to say that “the planets we knew about in the outer solar system” are composed of cold gas and ice, in contrast to Pluto, which is made up mostly of rock. What she doesn’t say here is that this makes Pluto similar to the terrestrial planets, which are also made of rock. There is no scientific rationale for the implied claim that rocky planets cannot exist in the outer solar system. Because she wants to make the point that Pluto is different, she contrasts it only with one class of planets, all but ignoring the other classes.

Her claim that Pluto is not much larger than the asteroids Ceres and Pallas is quite a stretch. Pluto has a diameter of 1,473 miles. In contrast, Ceres has a diameter of 580 miles, and Pallas has a diameter of 320 miles. These are not small differences.

The actual division here is between Ceres and Pluto on the one hand and Pallas on the other. Ceres and Pluto are spherical, rounded by their own gravity, while Pallas comes close to this threshold but is not quite there. According to the geophysical definition, this makes Ceres and Pluto planets of the dwarf planet subcategory. Pallas remains a protoplanet, or a planet that never completely formed.

Next, Stanway mentions Pluto’s “weird orbit,” which she describes as “tilted compared to all the other planets,” somehow failing to mention that Mercury is also tilted compared to most solar system planets. Furthermore, several exoplanet systems have been discovered in which multiple giant planets all orbit in different planes. If tilted orbits preclude objects from being planets, what then are these large exoplanets?

In discussing the discovery of the largest Kuiper Belt Objects starting around the year 2000, she describes Quaoar, Sedna, Orcus, Makemake, and Eris as “big space rocks,” with the subjective claim that “some of them looked uncomfortably similar to Pluto.” Why does she use the word “uncomfortably?” It seems like she is organizing the information to make a case that they cannot all be planets. In other words, she is using the same old argument that the solar system cannot have “too many planets,” an argument that has no scientific merit whatsoever.

Her description of the situation facing the IAU in 2006 is so subjective that it is laughable. She says, “Generations of people had grown up thinking Pluto was a planet and they didn’t want to let it go but the evidence was overwhelming: whatever the IAU decided would change our picture of the Solar System forever.”

Yet there was no such overwhelming evidence. The only “evidence” here showed that the solar system has more small planets than anyone previously thought. There was never an overwhelming consensus at the 2006 General Assembly that Pluto should be reclassified. In fact, the IAU’s own Planet Definition Committee, which had met for months in preparation for addressing this issue at the General Assembly, actually presented a resolution that included Ceres, Pluto, and Eris in the roster of planets. This was voted down, at which time proper procedure according to IAU bylaws called for the issue to be sent back to the proper committee.

Of course, we know that didn’t happen. Instead, the IAU violated its own bylaws, which require resolutions to first be vetted by the appropriate IAU committee before being put to the General Assembly, and several dynamicists who had their own agenda of wanting Pluto out hastily threw together a second resolution on the last day of the conference. By then, the chair of the Planet Definition Committee, Owen Gingerich, had gone home, as had most participants, assuming the issue would not be addressed again until the next General Assembly. Since no absentee voting was allowed, out of 10,000 members, just 424 took part in the vote. Of those 424, 333 decided that dwarf planets, a term first coined by Alan Stern in 1991, are not planets at all but a different type of object entirely.

This statement was not borne out by New Horizons, which revealed Pluto to have the same planetary processes and structures seen on the terrestrial planets, including some processes seen elsewhere in the solar system only on Earth and Mars.

Additionally, science is not done by voting but by consensus that develops over time based on new discoveries. Somehow, Stanway has no problem with throwing out the scientific method, instead appealing to “authority.”

Written in overly simplistic and somewhat condescending language, Stanway’s story concludes by saying Pluto “couldn’t be a planet anymore” because it doesn’t clear its orbit and because the IAU issued a ruling. She belittles opponents for “not wanting to let Pluto go,” completely ignoring the science-based objections to the IAU definition.

Never does she address the fact that orbit clearing is a poor, questionable requirement for planethood, as it is based solely on an object’s location and is biased against planets further from their parent star, which have larger orbits to “clear.” Planetary scientists have determined that if Earth were placed in Pluto’s orbit, it would not clear that orbit either. Therefore, the IAU definition results in the absurd situation of the same object being classed as a planet in one location and not as a planet in another location.

Nor does Stanway say even one word about the findings of the New Horizons mission. It seems she is fine with science by decree of “authority,” which went out 400 years ago with Galileo, but has no problem ignoring the data, which is what science is supposed to be about. Her article literally says nothing about Pluto’s intrinsic properties because for the IAU definition, those properties don’t matter—only location does.

Dwarf planets are not “a whole new type of object.” They are simply small planets. Ceres and Pluto both have subsurface oceans that could potentially host microbial life, and this could be the case for the other Kuiper Belt planets as well. We won’t know until we send probes to all of them.

Stanway’s story is an oversimplification that completely glosses over the ongoing debate and subsequent discoveries. It amounts to, the solar system only has eight planets because the IAU says so. This is a disservice to readers, and it is disappointing to see the University of Warwick publish such a one-sided article.

Pluto's glaciers change with its seasons

Pluto's glaciers change with its seasons

The Passage of Time Doesn't Make Something Right

I very unoriginally call it “The Day that Will Live in Infamy.” It is a day that should never have happened on which was held a vote that should never have happened.

It’s hard to believe 14 years have passed since that fateful day, when 424 IAU members presumed—wrongly—that they could speak for seven billion people on Earth, erroneously hijack a term coined by Alan Stern back in 1991, and dictate to the world that Pluto is not a planet.

The world wouldn’t have it.

Almost a decade and a half later, support for the alternative geophysical planet definition is only growing. Nothing hurt the planet definition adopted by four percent of the IAU more than the images and data New Horizons sent back from its reconnaissance of Pluto. Those images and data show an abundance of planetary processes, including active geology, layered hazes in Pluto’s atmosphere, interaction between Pluto’s atmosphere and surface, windswept dunes, flowing glaciers, cryovolcanism, and very likely a subsurface ocean.

With New Horizons’ findings, Pluto joins the growing list of ocean planets—worlds with subsurface oceans that could possibly harbor microbial life. Regardless of whether they are planets or moons, these worlds deserve a planetary subclass of their own, as they share the most unexpected of features—an underground ocean.

In spite of the new data, the IAU has done nothing to correct its error or even update resolution. More than 4,000 exoplanets have been discovered, yet the IAU has never taken any action toward defining them. Its planet definition requires an object to orbit the Sun rather than a star, meaning none of these 4,000 worlds count as planets. Neither do rogue planets, which cannot “clear their orbits” because they have no orbits to clear.

There are always people who make the argument that supporters of Pluto’s planethood should “let it go” because so much time has passed since the 2006 vote. That assumes the passage of time makes something wrong become right, which is a fallacy. Not only does the passage of time not change a wrong decision; knowledge gained over that time period actually strengthens the case that the decision was wrong.

It is the New Horizons team who are writing the textbooks about Pluto, and they see their flyby target as a planet. Their book, The Pluto System after New Horizons, will be published on December 8 of this year. It will be the most comprehensive study of Pluto until we follow up the flyby with an orbiter.

NASA is already funding a study by the Southwest Research Institute (SwRI) to explore the feasibility, nature, and cost of returning to Pluto with an orbiter. Unlike New Horizons, which could only photograph one side of Pluto in high resolution, an orbiter will reveal the mysteries of Pluto’s far side, which, as noted in this Nature article, already shows signs of liquid water, indicating the subsurface ocean might be global.

Tonight, at 7:30 pm Eastern time, show your support for Planet Pluto by listening to a presentation by Alan Stern for 28^th Parallel Productions via Facebook Live here: https://www.facebook.com/28thParallelProductions/ .

The IAU is learning the hard way that they cannot force a scientifically bad decision on the whole world. Planet Pluto lives, now and forever!

Explaining glaciers of solid methane and nitrogen on Pluto

ZME Science Article: Should Pluto be Promoted to a Planet Again?

This article presents more evidence of how much the tide has turned in Pluto's favor nearly 14 years after the IAU vote debacle. It even includes a tweet of mine from April 2019 regarding a public online vote on Pluto's status held after that month's debate between Alan Stern and Ron Ekers of the IAU.

https://www.zmescience.com/science/should-pluto-be-a-planet-0532/

Fifth Anniversary of New Horizons Pluto Flyby

Five years ago this month, on July 14, 2015, the New Horizons spacecraft made its historic flyby of Pluto, revealing a beautiful, complex planet and changing our view and understanding of that planet forever.

It is incredibly hard to believe that half a decade has passed since that amazing time, when Pluto became a rock star and made headlines around the world.

So many expected to find an inactive, dead world and were that much more surprised when instead, the spacecraft and its science instruments revealed a planet more geologically active than Mars, a planet with floating glaciers, windswept dunes, cryo-volcanoes, layers of atmospheric hazes, bladed terrains, mountains of water ice, interaction between surface and atmosphere, a likely subsurface ocean, and more than anything else, an iconic heart-shaped feature named Tombaugh Regio.

In the five years that have passed since then, numerous scientific papers have been written based on the data New Horizons returned. While it flew on past a second target and then proceeded to do more science studying the Kuiper Belt, planetary scientists, recognizing the flyby raised many more questions than it answered, have already begun advocating for returning with an orbiter.

An orbiter is the logical next step because it will be able to map the whole planet and provide high resolution images of the non-encounter hemisphere, which New Horizons was only about to image in low resolution.

Analysis of data returned by New Horizons seems to indicate Pluto not only harbors a subsurface ocean but likely has had that ocean since its formation four billion years ago. This puts Pluto in the growing category of ocean worlds in our solar system—worlds such as Ceres, Jupiter’s moons Europa and possibly Ganymede and Callisto, Saturn’s moons Enceladus and Titan, and Neptune’s moon Triton.

It may be that we need to recognize more subcategories of planets, specifically, these ocean worlds, any of which could possibly harbor microbial life and therefore completely alter our notions of what constitutes a star’s habitable zone.

The Pluto flyby was an exciting, thrilling accomplishment that stands in stark contrast to the troubled times we face now. But that also makes it a statement of hope, an Apollo moment, when people working together persevered in a long term effort that took a decade and a half to get to launch and then nearly another decade to reach its target. It is an inspiring achievement of people coming together, working with limited resources, building an extremely efficient spacecraft, and cooperating to quickly address any difficulties along the way. Flying a piano-sized spacecraft to a small, distant planet took precision, intellect, collaborating and problem solving—skills much needed around the world right now to address the various crises that plague this planet.

Beautiful Pluto inspired and gave hope to so many people. This mission stands as a tribute to the good people can do when they come together to work toward a difficult, ambitious goal.

Personally, I continue to hold the faith that scientists will succeed in returning to Pluto with an orbiter and that this return will be in my lifetime and the lifetimes of the many people who worked on the New Horizons mission and those who were enthralled by it.

For those interested, there are two new compilations of New Horizons' findings at Pluto. One is an e-book by Astronomy magazine, titled The Strange, Icy World of Pluto, which is available as a PDF for download at https://astronomy.com/-/media/Files/PDF/Marketing/Ebooks/Plutoebook.pdf and an academic textbook coming out next year titled The Pluto System After New Horizons, which is available for order at https://uapress.arizona.edu/book/the-pluto-system-after-new-horizons .

Cosmic Coffee, Cup No. 16 | Pluto and the Great Planet Debate

Cosmic Coffee, Cup No. 17 | The New Horizons Flyby of Pluto, 5 Years Later

"The Pluto Perspective: Memories of an Amazing Encounter"

This blog entry, with retrospectives written by members of the New Horizons team, celebrates the fifth anniversary of the spacecraft's Pluto Flyby on July 14, 2015.

http://pluto.jhuapl.edu/News-Center/Pluto-Perspective.php

To Pluto and Beyond with Alan Stern

This Planetary Society radio interview with New Horizons Principal Investigator Alan Stern commemorates the fifth anniversary of New Horizons' Pluto flyby.

https://www.planetary.org/multimedia/planetary-radio/show/2020/0708-2020-alan-stern-new-horizons.html?fbclid=IwAR1KkrScqsrbNrqVVhyAvvNjZc1UIhrT55C-9f45QbX6NFGY4ubMiO2_-bs

Pluto's subsurface ocean may date back to planet's formation

 Pluto's subsurface ocean may date back to planet's formation

SOFIA data sheds new light on endurance of Pluto's atmosphere

 SOFIA data sheds new light on endurance of Pluto's atmosphere

More Evidence that Pluto Might Have a Subsurface Ocean

More Evidence that Pluto Might Have a Subsurface Ocean: The impact that created Pluto’s 'heart' may have rippled through its ocean and damaged its rear

Spring Equinox 2020 at Lowell Observatory

Custer Institute Observatory Declares Pluto is a Planet

Custer Institute Observatory Declares Pluto is a Planet: The Board of Directors of respected Astronomical Observatory, Custer Institute in Southold, NY has recently created a resolution declaring that Pluto is again a planet.

Planet Pluto Discovered 90 Years Ago Today

Today, February 18, 2020, marks the 90^th anniversary of Pluto’s discovery by 24-year-old Clyde Tombaugh at the Lowell Observatory in 1930. The little planet that could has now been a part of our science, history, and culture for nine decades!

The Lowell Observatory is hosting an “I Heart Pluto” event complete with talks by leading planetary scientists, including Alan Stern; Charon discoverer James Christy; astronomer Larry Wasserman, Lowell astronomer Will Grundy, Lowell historian Kevin Schindler, and Tombaugh’s son Alden Tombaugh.

Pluto-themed art is on display for the event, and participants are being treated to tours of the renovated telescope, known as an astrograph, that Tombaugh used to take the photographic plates of the sky from which he discovered Pluto. Attendees also have the opportunity to see the blink comparator Tombaugh used to “blink” or move back and forth between two pictures of the same part of the sky taken several days apart to search for something that moved against the background stars.

On February 18, 1930, 24-year-old Tombaugh found that tiny dot that moved against the same field of stars taken on January 23 and January 29 of that year.

To commemorate the occasion, Mother Road Brewing Company, together with Lowell astronomers, has created a special “Pluto Porter” brew. Celebrants will dine today at Flagstaff’s Karma Sushi Bar and Grill, which was The Black Cat Café in 1930, where Clyde Tombaugh dined on the afternoon of the day he found Pluto.

Karma Sushi Bar and Grill has even created a special “Pluto Roll” for the occasion.

This time around, Tombaugh is getting far more recognition and accolades than he did upon making his discovery. Back in 1930, the Lowell Observatory credited the late Percival Lowell, founder of the observatory, who had died in 1916 after devoting his life to searching for a planet beyond Neptune. Tombaugh’s name was not even mentioned in a circular released by the Observatory announcing the discovery. Instead, he was referred to as a “junior astronomer.”

Personally, I deeply regret not being able to attend this Pluto-lovers’ celebration at the Lowell Observatory, much as I regret never having met Clyde Tombaugh.

If he were here, Tombaugh would have a lot to celebrate. Over the past five years, and especially within the last year, consensus among both scientists and members of the public that Pluto is a planet and that the IAU got it wrong in 2006 has been steadily growing. Even the media has picked up on this, with some coverage acknowledging the many problems inherent in the 2006 vote by just four percent of the IAU’s members.

What has played the largest role in turning the tide in favor of Pluto’s planethood is without question the New Horizons flyby data. One simply has to look at the varied terrains on Pluto’s surface to see what is obviously a planet. Before the flyby, many scientists expected Pluto to be a dead rock. Instead, the spacecraft and its science instruments revealed a geologically active world with weather, a hazy atmosphere, interaction between atmosphere and surface, floating glaciers, windswept dunes, water ice mountains, cryovolcanism, and very likely a subsurface ocean.

The latter adds Pluto to a growing list of ocean worlds that could potentially host microbial life. Solar system worlds known or suspected to harbor subsurface oceans include Ceres, Jupiter’s moon Europa, Saturn’s moons Titan and Enceladus, Neptune’s moon Triton, and now Pluto.

From the time of its discovery until today, Pluto has had a hold on people, has fascinated so many to the point that both scientists and journalists are often puzzled. What is it about this world that is so compelling? Those supporters who claimed that children who learn an eight-planet solar system will not share this excitement over Pluto have largely been wrong. Children as young as three, four, and five have gotten media coverage for rejecting the notion that Pluto is not a planet! Many school age children refuse to see Pluto as anything but a planet.

Continued opposition to the IAU demotion is not limited to children. More and more scientists are gradually coming on board the Pluto-is-a-planet train. After a debate last April between Alan Stern and Ron Ekers of the IAU, audience members voted overwhelmingly in favor of Pluto’s planet status.

Just last week, an article was published in a North Jersey newspaper about the 90^th anniversary of Pluto’s discovery, in which an astronomer who gave a talk about Pluto last April was interviewed. He reported that after three people approached him following his talk and made the case for Pluto’s planet status, he spent a lot of time considering their points and finally came to agree with them. While he doesn’t mention any names, I was at that event with a friend, and it is clear that two of those three people were my friend and me!

In 2015, as the Pluto flyby approached, I had fears that even though New Horizons’ findings would excite and fascinate people, they would not be enough to change people’s minds. What if the reactions of scientists, reporters, and members of the public were, yes Pluto is fascinating and beautiful, but it is still not a planet? Some did react that way, but over time, the New Horizons data and images are working their magic.

Just this month, a paper by planetary scientist and astrophysicst Tanguy Bertrand of the NASA Ames Research Center was published in the Journal of Geophysical Research: Planets noting that Pluto’s iconic heart feature, which definitely made people fall in love with the small planet, actually behaves like a “beating heart” in controlling Pluto’s winds and possibly even shaping its surface features.

Pluto has weather, and understanding that weather, which is based on a hydrologic cycle involving nitrogen, could actually help scientists better understand Earth’s atmosphere, Bertrand stated. And it has geological processes seen elsewhere in the solar system only on Earth and Mars! Alan Stern once described Pluto as the most Earth-like solar system planet other than Earth itself!

In 90 years, we have gone from a tiny dot that could not be resolved into a disk by the world’s largest telescopes to a gorgeous planet, complete with a beating heart! If only Tombaugh could have seen and known the full nature of his discovery!

Every day, that discovery is defying the IAU and mainstream media in revealing itself as a planet. As New Horizons planetary scientist Cathy Olkin noted, “I naturally refer to Pluto as a planet because that seems like the right moniker. It has an atmosphere; it has interesting geology; it orbits the sun; it has moons. 'Planet' just seems right to me.”

Let’s raise a toast to celebrate the discovery of this iconic, unforgettable planet and 90 years of it inspiring people of all ages, backgrounds, and walks of life. And then, let’s get to work on sending an orbiter to unravel even more of Pluto and its system’s mysteries.

Looking Back: A New Horizons New Year's to Remember by Alan Stern

http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20200102