2 years ago
Monday, February 20, 2023
Saturday, February 18, 2023
Planet Pluto Discovered 93 Years Ago Today, February 18, 1930
On February 18, 1930, exactly 93 years ago today, 24-year-old Clyde Tombaugh discovered Planet Pluto while blinking between two photographic plates of the same part of the sky taken six days apart at the Lowell Observatory in Flagstaff, Arizona.
He found a tiny dot that moved against the background stars from one plate to the next and thus succeeded just over a year after arriving at Lowell Observatory to take up the search for a new outer solar system planet, begun many years earlier by observatory founder Percival Lowell.
Now close to 130 years old, the Lowell Observatory is today holding its annual “I Heart Pluto” celebration to commemorate the discovery. The 13-inch Lawrence Lowell telescope Tombaugh used to take the photographic plates, recently restored, still sits within its original dome and is viewed by visitors every day.
Discoveries are not always well understood at the time they are made. In Pluto’s case, the new planet was too small to be resolved into a disk, leading some scientists to speculate that it might be a moon of a not-yet discovered larger parent planet.
Eventually, telescopes became powerful enough to resolve Pluto into a disk, but even Hubble images taken during the 1990s were fuzzy. The real revelation of Pluto in all its glory happened in 2015, when the New Horizons spacecraft flew by that world, imaged its varied terrains, and returned data that is still being studied and analyzed today.
Tombaugh and his fellow astronomers in 1930 had no way of knowing that they had found the first of many small planets in what is now known as the solar system’s third zone. They certainly had no inkling that the newly discovered world was one of many solar system objects that has a subsurface ocean possibly capable of hosting microbial life.
With the recent renewed interest
in UFOs, it is important to remember that as of today, we have not
even determined whether any other place in our own solar system
harbors life. What we have discovered is that small planets Pluto and
Ceres, as well as various moons of the gas and ice giants, likely
have oceans beneath their surfaces that could potentially host
microbes. Among that growing list of worlds are Jupiter’s moons
Europa, Ganymede, and Callisto; Saturn’s moons Enceladus, Titan,
and possibly even Mimas; Neptune’s moon Triton, and possibly
Pluto’s binary companion Charon.
Distant planets like
Eris and Sedna could also potentially host such oceans, but we won’t
know until we send probes to study them up close.
On
February 18, 1930, Clyde Tombaugh had no way of knowing that he had
not only unlocked a third zone of the solar system, but also
discovered a new class of ocean worlds that could be the prime
locations for life taking hold beyond the Earth.
While it
is clear that any extraterrestrial life in our solar system is
limited to microbes, finding evidence of such life on any world would
be one of the most significant scientific discoveries in history, as
it would confirm life got started on worlds other than Earth.
Tombaugh also could not have known that the world he discovered was not a dead rock, but a geologically active planet that appears to have an internal heat source. No one expected something like this so far from the Sun. Today, the discovery of Pluto’s complexity and activity raises the possibility that other, even more distant worlds, could also be active planets.
Our technology is not yet at the level of being able to discover Pluto-sized planets in other solar systems, but the ability to do so is likely just a matter of time. While his search was for a gas giant planet, Tombaugh discovered the first in a new subclass of planets, the dwarf or small planets, largely but not solely present in the outer solar system. It is reasonable to hypothesize that other solar systems could also have regions like this, with scattered small planets that might be hiding subsurface oceans.
Some in the astronomy community did not give Tombaugh sufficient credit for his discovery back in 1930. His name was not even mentioned in Lowell Observatory’s press release announcing the discovery. Some astronomers of the day even looked down on him because he was a 24-year-old with just a high school education, not an astronomy PhD.
Yet even here, Tombaugh set a new trend though it would not become a “thing” until many decades later. This trend is that of astronomical and planetary discoveries being made by ordinary citizens, amateur astronomers, and even kids, who don’t have PhDs, but are passionate about the universe. Internet and telescope technology have opened the discovery process to interested citizens around the world, who have discovered exoplanets, brown dwarfs, supernovae, etc.
In so many ways, Tombaugh was far ahead of his time. This is also true of his staunch support of Pluto’s planethood. Doubts about that began not in 2005 but in 1930, soon after its discovery. Yet Tombaugh never wavered in his position even though he did not live to see the New Horizons flyby. Today, we know that Pluto is actually part of a binary system with Charon, meaning it is not one but two planets! The system’s four smaller moons orbit not Pluto itself but the center of gravity between Pluto and Charon.
This is a day to
celebrate Planet Pluto and its opening of new frontiers in solar
system and planetary studies. I personally wish I could be at Lowell
Observatory’s I Heart Pluto celebration and hope to to be there for
the centennial in 2030.
This year’s celebration will
conclude with two talks that will be livestreamed online. The first,
“The
Future of New Horizons,” will be presented by Alan Stern on
Sunday, February 19, at 7 PM Mountain Standard Time, which is 9 PM
Eastern time. The second, “New
Horizons: NASA’s Mission to Pluto and the Kuiper Belt,” by
New Horizons engineer and mission operations manager Alice Bowman,
will be presented on Monday, February 20, at 7 PM Mountain time/9 pm
Eastern time.
Happy Discovery Day, Planet Pluto!
Wednesday, February 15, 2023
I Heart Pluto Festival Returns to Lowell Observatory
It is almost the 93rd anniversary of Pluto's discovery on February 18, 1930, and that can mean only one thing--Lowell Observatory's annual I Heart Pluto celebration is back! Find out more here! While celebrations on February 18 will be in person at Lowell Observatory, there will be two talks livestreamed online on YouTube, one on February 19 and the other on February 20, as follows:
Sunday, Feb. 19, 7 pm: The Future of New Horizons: An Interview with Dr. Alan SternMonday, Feb. 20, 7 pm: The Latest News from Pluto and Arrokoth, with Alice Bowman, Engineer/New Horizons Mission Operations Manager, Johns Hopkins University Applied Physics Laboratory
Wednesday, December 21, 2022
Winter Solstice 2022
We
have once again reached that noteworthy milestone—in the Northern Hemisphere,
it is the Winter Solstice, the shortest day and longest night, the turning
point of the year when darkness stops advancing, and the Sun appears to stand
still in the sky before reversing course.
It’s been quite a year for space exploration. The James Webb Space Telescope successfully launched just about a year ago in spite of endless delays and repeatedly going over budget. It performed flawlessly in unfurling its sunshield and mirror, reaching its Lagrange Point position, and returning stunning images that open a new era of exploration for astrophysics, planetary science, and cosmology.
Another long delayed project, our return to the Moon, also finally launched this year. Artemis I sent back beautiful close up photos of both Earth and Moon, reminiscent of the famous Apollo 8 image captured at this time of year back in 1968—a picture that had a profound impact on many and played a key role in launching the environmental movement.
While 2022 has certainly had its share of challenges, it brought to fruition projects some doubted would ever launch, revealing that late does not mean never and reminding us that if something really matters, giving up should never be an option.
People who have had the good fortune to travel to space note it brings a life-changing perspective. From there, no borders are visible, just one fragile planet, now home to 8 billion people and numerous other life forms.
We all, not just world leaders, need that change in perspective because the problems our home planet faces cannot be addressed by just one group of people or one country. The only way we have any hope to stabilize our climate, mitigate the worst effects of climate change, and clean up our air, land, and water, is to come together as one people on one planet.
Too often, people look at the year-end holidays in ways that divide us, at a time when, more than ever, we need to unite to preserve our planet’s habitability for future generations—so we can one day explore the solar system and eventually the stars.
This day, at its core, is about hope. It is about light and life, known by the
Romans as the Birthday of the Unconquerable Sun. This makes it an ideal time to
treasure the gift of our planet and affirm the amazing things we can accomplish
when we come together for a common goal—like launching JWST and sending
astronauts to the Moon.
If we can do those things, we can save our planet for future generations. May the year that starts with the return of the light inspire us all to come together and choose a future of light and life.
“We are the power in everyone
We are the dance of the Moon and Sun
We are the hope that cannot hide
We are the turning of the tide!”
Friday, October 14, 2022
Why Space.com Article is Wrong about Pluto's Planet Status
Space.com is usually a very credible information site about all matters space and astronomy, which is why its October 23, 2022 article, “Why is Pluto Not a Planet?” is so disappointing in its blatant one-sidedness.
More than 16 years after the controversial IAU vote on a highly flawed planet definition, it is difficult to understand why this site would publish an article that is extremely selective in every one of the sources it uses as references. From the IAU web page to Mike Brown to Ethan Siegel, formerly of Forbes, to a Neil Tyson video, the article refers almost solely to supporters of the IAU definition and completely excludes the many essays and articles written from the opposing point of view.
The article is problematic starting with its title, which, instead of acknowledging the ongoing debate over planet definition and Pluto’s status, simply states the IAU view as fact. This misleading title essentially presents the IAU view as “the truth” rather than as one view in an ongoing debate, and this notion is repeatedly assumed in the article, in spite of very sparse references to dissenting views.
Yet, there is absolutely NO reason to give the IAU position privilege as somehow being the “official” one in use. It is simply one of several definitions currently used by planetary scientists.
We need to address the factual errors in this article. Like many writings on this subject over the last 16 years, the writers cite Ceres’s discovery as a planet and subsequent demotion to asteroid in the mid-19th century as an earlier example of what happened to Pluto. However, they fail to acknowledge the other, crucial part of Ceres’s history.
Because it is very small, Ceres could not be resolved into a disk by 19th century telescopes. At the time, it therefore made sense to demote it to one of many asteroids in the belt between Mars and Jupiter. However, since then, Ceres has been found to be spherical, meaning unlike nearly every asteroid in that belt, it is squeezed into a round or nearly round shape by its own gravity. Most asteroids are simply rubble piles shaped by chemical bonds. The threshold for an object being spherical, in a state known as hydrostatic equilibrium, is crucial because this is when objects begin to experience geology and the complex processes seen on rocky planets.
In 2015, NASA’s Dawn mission revealed Ceres to have these complex features, including cryo-volcanoes and a possible subsurface ocean that could potentially host microbial life. These findings indicate the 19th century demotion was in error and that Ceres is more like the larger rocky planets than almost all objects in the asteroid belt, with the exception of Vesta and Pallas, which appear to have once been spherical only to have had a large portion knocked off during impacts with other objects.
While some, including the writers of this article, invoke Pluto’s eccentric orbit and 17-degree tilt to the ecliptic as reasons for demoting it from planethood, the fact is several exoplanet systems contain multiple giant planets all orbiting in different planes. At least two systems have giant planets that cross one another’s orbits. And the ecliptic, often wrongly depicted as the path of the Sun, is actually the plane of the Earth in its solar orbit. Requiring objects to orbit in the same plane as Earth is a violation of the Copernican principle, which essentially states that Earth is just another planet, not the center of anything. And if giant objects that cross the orbits of other giant planets in their systems are not planets, what then are they?
The next inaccuracy in the Space.com article is its attribution of Eris’s discovery solely to Mike Brown. While Brown often presents himself as Eris’s sole discoverer, the fact is, Eris was discovered by a team of three scientists, the other two being Chad Trujillo and David Rabinowitz. Significantly, both Trujillo and Rabinowitz reject the IAU planet definition. Rabinowitz even signed a petition with hundreds of planetary scientists back in 2006 in response to the IAU definition, saying they would not use it.
The reference to the late Brian Marsden is also problematic, as Marsden, who apparently had a long feud with the late Pluto discoverer Clyde Tombaugh, was obsessed for decades with demoting Pluto so it could be put under his auspices at the IAU Minor Planet Center. Like Brown, he is a scientist who appears to have had his own agenda from the start.
While the article does acknowledge that only 424 IAU members voted on the controversial planet definition in 2006, it fails to note that this vote was held in violation of IAU bylaws, which prohibit putting a resolution to the floor of a General Assembly without first vetting it by the proper IAU committee. It also fails to mention that these 424 people were largely not planetary scientists but other types of astronomers, that they represented only four percent of the IAU’s membership, that no electronic or absentee voting was permitted, that 91 of the 424 voted for dwarf planets to be classed as a subclass of planets, and that an equal number of professional planetary scientists signed the afore-mentioned petition rejecting the IAU definition within days of its adoption.
Additionally, the writers fail to mention that when initially coined by Alan Stern in 1991, the term “dwarf planet” was intended to designate an additional class of small planets, not to designate a class of non-planets. In its unauthorized vote, the IAU essentially misused the term “dwarf planet” based on the fiction that dwarf planets are fundamentally different compositionally than their larger counterparts, a position proved false by the findings of the Dawn and New Horizons missions.
Even Neil Tyson is on record saying he has no problem with dwarf planets being considered a subclass of full planets!
As the article writers note, New Horizons found Pluto to have active geology; diverse features including windswept dunes, varied terrains, a layered atmosphere, cryo-volcanism, interaction between atmosphere and surface, and a likely subsurface ocean. Some complex features discovered on Pluto exist elsewhere in the solar system only on Earth and Mars!
To make matters worse, the article never acknowledges the alternative geophysical planet definition, which is preferred by most planetary scientists, beyond a vague mention of a 2017 proposal that “defined a planet as a round object in space that’s smaller than a star.” This is a major disservice to the proposal, presented to the Lunar and Planetary Science Conference that year, which centers planet definition on an object’s intrinsic properties rather than on its location, which the IAU definition does.
Most problematic is the article’s inherent assumption that only the IAU has the ability or power to determine what a planet is. Conveyed throughout this article, that sentiment can be seen in the statement noting Alan Stern and David Grinspoon’s 2018 Washington Post article urging reconsideration of planet definition “have fallen on deaf ears so far, and it seems unlikely theIAU will revisit the controversy any time soon.”
If such pleas to the IAU fall on deaf ears, and the organization refuses to
address new data returned by the Dawn
and New Horizons missions, then it is
time to consider other venues for this discussion. The notion of science being
decided by any type of “authority” went out with Galileo’s discovery of Jupiter’s
moons over 400 years ago. A science publication like Space.com should know better than to appeal to any “authority”
regarding scientific matters.
Finally, the article falls back on attributing opposition to the IAU decision to emotion, as seen in its Mike Brown quote, “Nostalgia for Pluto is not a very good argument, but that’s basically all there is. Now, let’s get on with reality.”
This comment is not only demeaning; it is also blatantly false. Scientists, amateur astronomers, and members of the public oppose the IAU definition not because of nostalgia or emotion but because the geophysical definition, which classifies objects first and foremost by their intrinsic properties, simply makes more sense based on what we have discovered about these objects. Brown does not get to unilaterally end the debate and get the last word simply because he wants to do so.
There are so many scientists and publications that articulately present the other side of this debate. I urge Space.com to do a better job in presenting this fascinating controversy to give readers a comprehensive understanding of both positions, allowing them to decide for themselves where they stand.
The authors of this article are right on one thing: This debate will continue for the foreseeable future.
Sources in response to those presented
in the Space.com article:
Note: I wrote the response to the IAU statement and to Siegel’s Forbes article and embrace my role in
this debate on Twitter with the handle @plutosavior
.
I have covered the New Horizons mission for the website Spaceflight Insider since 2014 though the opinion expressed here is solely my own and not necessarily that of the site or its editors.
“Responding to the IAU: Pluto and the Developing Landscape of the Solar System,” a point-by-point rebuttal to the IAU statement:
http://laurelsplutoblog.blogspot.com/2013/02/responding-to-iau-pluto-and-developing.html
https://www.hou.usra.edu/meetings/lpsc2017/eposter/1448.pdf
“An Organically Grown Planet Definition,” by Alan Stern and Kirby Runyon, https://astronomy.com/magazine/2018/05/an-organically-grown-planet-definition#.Wv3x0d97CCI.blogger
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