Journey Into Darkness

 

Nonfiction – by Peter Jekel



The real meaning of enlightenment is to gaze with undimmed eyes on all darkness.

Nikos Kazantzakis

Astronomy rarely if ever causes the public to protest, and protest loudly, due to a controversy. Sure, astronomers, astrophysicists and cosmologists may disagree with one another in terms of a theory, observation or hypothesis, but the disagreements making their way into mainstream media are unheard of. Never in the history of astronomy was there more mainstream controversy than when Pluto was demoted by the International Astronomical Union from a planet to a dwarf planet in the Kuiper Belt of our solar system in 2005. The controversy was somewhat ironic as well since Pluto really did not garner a lot of attention after its discovery being that the world was on the edge of the solar system.

Pluto survived its demotion and perhaps gained notoriety as a result. With the publicity around the demotion coupled with the flyby by NASA’s New Horizons spacecraft on July 14, 2015, Pluto’s importance grew. Pluto went from being the ninth planet in the solar system, to a dwarf planet to one of the most interesting worlds out there. 


 

The history of the discovery of Pluto began in the 1840’s when French mathematician Urbain Le Verrier analyzed the anomalies of the motion of the planet Uranus (Neptune had not yet been discovered).  Once the planet Neptune was discovered in 1846, the anomalies of Uranus’ orbit still were not satisfied. Another planet had to be out there beyond Neptune.

 

It was not until 1906 that American astronomer Percival Lowell began his search for the predicted ninth planet. Lowell was an astronomer who knew how to engage the public’s curiosity. After all it was Lowell who publicized the “canali” of Mars discovered and hinted as being construction projects of an intelligent race by Italian astronomer Giovanni Schiaparelli in 1877. In fact, Lowell wrote three books on the topic. For his work on Pluto, he used the term Planet X in all likelihood to enhance the mystique around his work. Even though he relished the limelight, he did good work. In 1909, he and fellow astronomer William Pickering suggested the coordinates of the location of the mysterious Planet X. In fact, Lowell actually did discover Pluto but failed to recognize the world’s image captured on two photographs that he had taken from his Lowell Observatory on March 19 and April 7, 1915. Though Lowell did not officially discover Pluto, it was his pioneering efforts behind the search for Planet X that led to its eventual discovery. 

 

Due to a legal battle between Lowell’s widow—Lowell died in 1916—and the Lowell Observatory, the search for Planet X was put on hold until 1929. American astronomer, Clyde Tombaugh, was given the task of resuming the search for Planet X. He did not let his backers down as he discovered Pluto on February 18, 1930. The discovery was kept secret, though, until March 13, Percival Lowell’s birthdate. Not science fiction, but fiction nonetheless, Michael Byers wrote the novel Percival’s Planet that dramatizes the search and eventual discovery of Pluto by Tombaugh.

 

The newly discovered world was named Pluto after the Roman god of the underworld, perhaps in keeping with the fact that Pluto lies in the near perpetual darkness of what was considered the edge of the solar system at the time. Some have hinted that the planet’s name may also have another reference to Lowell’s work, with the first two letters of the planet being the same as the initials of Pluto’s astronomer cheerleader Percival Lowell.

 

Ironically, horror writer H. P. Lovecraft started writing his novella Whisperer in the Darkness, (it was published in August 1931) in February 1930 about the ninth planet being used as an alien base of operations almost concurrently with the time of the dwarf planet’s actual discovery.

 

Since Pluto appeared as just a point of light in the night sky, it garnered little interest amongst astronomers. Its average distance from the Sun is approximately 6 billion kilometers. In fact, if one were able to stand on Pluto and look back at the Sun, you would see a disc that appears as bright as a full moon in the Earth’s night sky. In spite of being discovered, Pluto remained as isolated as it ever was.

 

Pluto garnered a small flurry of excitement when in 1978, James Christy and Robert Harrington, both of the United States Naval Observatory, discovered a moon orbiting Pluto. At first, they initially thought that the bulbous projection on the photograph of Pluto was just a smudge. However, continued observations demonstrated that the “smudge” would eclipse 6.4 days later and would continue to do so on a regular basis; the “smudge” became a moon orbiting the main dwarf planet, Pluto.

 

The moon was named Charon, after the ferryman who transported the souls of the dead across the River Styx to Pluto, god of the underworld. Charon has the unique feature in the solar system of being the only known satellite to travel in an asynchronous orbit with its “parent” planet.

 

Pluto and Charon are not so much a planet (or dwarf planet) and its satellite, but a double planet. In spite of support for this proposal, the International Astronomical Union, in August 2006, abandoned the idea. Nonetheless, no one can deny that the link between Pluto and Charon is indeed unique amongst the objects of the solar system.

 

Initial estimates of the size of Pluto and Charon were based on the fact that the two objects eclipsed each other regularly and therefore, were thought to be almost the same size. In 1994, with the clarity offered by the Hubble Space Telescope accurate measurements of Pluto and Charon were actually calculated. Pluto has a diameter of 2320 kilometers and Charon’s is 790 kilometers. Most interesting though is that Charon orbits Pluto at a distance of only 19,000 kilometers, a mere baby step in the vastness of the solar system.

 

The discovery of Charon also allowed astronomers to calculate the mass of Pluto (1.3 X 1022 kilograms) and also of Charon (0.16 X 1022 kilograms), based on their respective orbits around one another. The orbits of Pluto and Charon have a very peculiar interaction in that both bodies are locked tidally against one another.

 

One novel, by Bob Shaw, The Ragged Astronauts, seems to have been written with Pluto and Charon in mind. A major difference though is that Shaw’s worlds are more habitable for humans than the icy cold of Pluto and Charon.

 

It is truly amazing how our knowledge of Pluto has expanded since 1978. Pluto is now known to not only have one moon but five. In addition to the already discovered Charon, Styx, Nix, Kerberos and Hydra were subsequently identified.

 

In 2012, some astronomical observations indicated that Pluto had a quasi-moon called 15810 Arawn. A quasi-moon is a body that has a co-orbital resonance and stays with the parent planet for many orbital periods. New observations from New Horizons disproved this original theory. 


Two of the new moons were discovered by astronomers of the Hubble Space Telescope’s Pluto Companion Search Team as part of astronomical preparations for the New Horizons mission. On May 15, 2005, they discovered Nix and Hydra. On July 20, 2011, they discovered Kerberos, while searching for rings around Pluto and finally Styx was found on July 7, 2012 in an effort to forecast potential hazards to the New Horizons spacecraft. 

At least one science fiction author wrote of the moons of Pluto. In Simon Petrie’s “The Man Who…,” miners find anomalous features on Kerberos. 

 

It is believed that the moon system of Pluto was created by a collision of a large object with Pluto not unlike the object that impacted Earth early in her history to eject material that would eventually become our Moon. The nearly circular orbits of Pluto’s moons suggest that this is most likely rather than being captured objects of the Kuiper Belt as might be expected. 


Interestingly enough, science fiction writer Edmond Hamilton wrote a novel in 1940, Calling Captain Future, where he describes Pluto as having three moons. Though he predicted the moons’ discoveries in 1970 in the novel, he was not far off since Charon itself was first found in 1978.


There are several theories to explain the origin of Pluto itself. At least one science fiction author, Clifford Simak, suggested an artificial origin for Pluto in his short story, “Construction Shack.” James Hogan’s Gentle Giant series, describes, in the first novel, Inherit the Stars, that Pluto is actually one of the remains of the planet Minerva that exploded in the asteroid belt of the solar system around fifty thousand years ago.  


An early theory is that Pluto is an escaped moon of Neptune. One has to look at Neptune’s interesting moon, Triton, to understand this theory. Triton orbits its home world in a retrograde fashion, the only moon in the solar system to do so. This origin theory suggests that Pluto and Triton collided in the distant past. Pluto was ejected by the cataclysmic collision into its current highly eccentric orbit. Alternatively Triton’s orbit was spun around due to the energy of the collision. Larry Niven’s first novel of his Known Space series, World of Ptavvs, suggests this very origin for Pluto. Recent calculations of the planetary dynamics of both worlds have come into conflict with this theory; in fact, scientists now claim that this origin theory for Pluto is impossible.


Instead Pluto, since it was demoted to a dwarf planet, is now classed as the largest member of the Kuiper Belt. The Kuiper Belt is a circumstellar disc that orbits the Sun from around thirty to fifty astronomical units (an astronomical unit is the distance between Earth and the Sun). Ironically, though named after Dutch-American astronomer Gerard Kuiper due to the fact that he hypothesized its existence, Kuiper felt that nothing would be found today as he postulated that gravity would have played havoc with the area and swept the bodies either out of the solar system or into its inner reaches long before the present day. The Kuiper Belt is similar to the asteroid belt of the inner solar system in that it is made up of mainly small bodies (mostly under 100 kilometers in diameter) left over from the solar system’s formation.  However unlike the asteroid belt in which the objects are predominantly rocky or metallic, the Kuiper Belt objects are mainly made of ices of  methane, ammonia and water.


Pluto now has a size competitor in the Kuiper Belt. Eris, discovered in September 2006 by a team at Palomar Observatory is more massive than Pluto but Pluto still retains its size title in that it is slightly larger by volume. Eris even has its own moon, named Dysnomia. One author, Hugh Walters, wrote a novel, Passage to Pluto, about the discovery of another large world near Pluto which astronauts in the story dub Planet X.

 

Though the Kuiper Belt is considered lifeless mainly due to the cold, some science fiction authors have not been deterred and have come up with biologically credible possibilities. Camelot 30K by Robert Forward and “Sunpeople” in Vacuum Diagrams by Stephen Baxter both extrapolate heavily with low temperature chemistry to hypothesize life forms at these extreme reaches of the solar system. So never say never and when we delve further into what we know of Pluto, now a Kuiper Belt object, one will see why.

Much like its Kuiper Belt companions, Pluto’s orbit is very different from that of the planets. In fact, this was but one major piece of evidence that moved Pluto from planetary status to that of a dwarf planet. It orbits the Sun every 248 years. In addition, unlike the other planets which orbit in almost circular orbits along a relatively flat ecliptic, Pluto has a highly eccentric orbit that is inclined at over seventeen degrees to the ecliptic, more in keeping with its Kuiper Belt brethren.


Until the arrival of New Horizons, not a lot was known about the surface of Pluto. Now astronomers see a world of wonders. Most of the surface of Pluto is shrouded in an ice sheet predominantely made up of frozen nitrogen with a small amount of methane and carbon monoxide. Sounds boring until you start looking more closely. The surface of Pluto is probably one of the most colourful in the solar system. Colours of black to red to orange and yellow have been detected on the planet. The colours are likely due to patches of tholins which are created by charged particles from the distant Sun, reacting with frozen surface nitrogen and methane. Charon also has a number of colours on its surface much like Pluto due to tholins. Instead of frozen nitrogen, though, Charon’s surface is made predominantely of water ice.


There are mountains on Pluto mainly in the western area known as Sputnik Planum. They are not like any mountains that we have here on Earth. Instead they are made predominantely of water ice and literally float on top of the nitrogen ice, thereby acting more like giant icebergs than true mountains. Some of these mountains of ice extend up to forty kilometers across and reach up to five kilometers above the surface. These “mountains” are estimated to be only around ten million years old, relatively young in light of the fact that Pluto is literally billions of years old.

 

Pluto’s sister world Charon also has interesting geological features. Deep canyons run along the equatorial belt for up to one thousand kilometers and can be as deep as nine kilometers in parts. One photograph by New Horizons shows a mountain feature that has literally stumped geologists as to its origin. The feature appears to be a large mountain that is sitting in a pit described by scientists from the New Horizons project as ‘a mountain in a moat.”

 

In the western part of Sputnik Planum is a series of dunes formed by wind. Like the mountains of Pluto, the dunes are not anything like what we have here on Earth. Instead of silica sand dunes as we have on Earth, the dunes of Pluto are likely made up of methane ice particles around two to three hundred micrometers in diameter. Even in the weak sunlight hitting the surface of Pluto, there is enough energy to sublimate the nitrogen ice which in turn, lofts the methane ice particles into the thin atmosphere which blows them lightly around.   


Whereas a lot of the surface of Pluto is smooth, other parts look pitted. Some areas show evidence of enormous fissures which appear as if the crust of Pluto has expanded and broken open. The likely explanation of this phenomenon is that there is a subsurface ocean that is slowly cooling thus stressing the ice surface. The sub-surface ocean is probably made up of water that exists at between 100 and 180 kilometers deep based on experiments carried out at Brown University. 


Where there is a water ocean there is also the possibility of life. Even before the speculation of an under ice ocean, life on Pluto has been speculated for years by writers.


In Robert Silverberg’s World’s Fair, 1992, he describes a mission to Pluto that collects five crab-like Plutonians to return to Earth for further study. Silverberg also wrote a short story with Pluto as the setting entitled “Sunrise on Pluto”; in that story, he describes an alien life form that survives on the planet. Stephen Baxter, in his short story, “Gossamer,” two women crash land on Pluto when the wormhole that they are travelling in collapses, only to discover a snowflake-like life form that reproduces in a complex interaction with Pluto’s large moon, Charon. Gregory Benford’s Sunborn  describes an intelligent life form that lives on Pluto along the shores of a nitrogen sea. In Larry Niven's "Wait it Out,” an explorer of Pluto becomes marooned but in his isolation he discovers a life form that uses extreme low-temperature chemistry and physics to survive the extreme cold.

Much like Lovecraft did earlier, several authors have looked at Pluto as a possible alien base. One, First Lensman, by E. E. Doc Smith, describes an alien race colonizing the cold planet, ignorant of the life-bearing world of Earth. Donald Wollheim wrote, Secret of the Ninth Planet, with Pluto serving as the base for an alien race bent on tapping our Sun’s energy to power their own civilization. In Kim Stanley Robinson’s Icehenge, mysterious monolithic monuments are found at Pluto’s north pole.


The surprises from Pluto and Charon keep on giving. At the south pole of Pluto, there appear to be ice calderas at the summits of two mountains called Wright Mons and Piccard Mons. They are both at least sixty kilometers wide and up to several kilometers tall. In shape and size they are very similar to the volcanoes of Hawaii, but instead of hot lava spewing out, they eject ices from below, further evidence of a buried subsurface ocean. Predating the discovery of these cryovolcanoes by New Horizons, Dr. Edward Rhodes wrote a novel entitled A Space Odd-yssey, about a hunt for space pirates which describes these cryovolcanoes.

 

Pluto is not alone either in the possibility of having a subsurface ocean. Its sister world, Charon may possess one as well. In 2007, observations by the Gemini Observatory indicated patches of water crystals and ammonia hydrates on the Charon’s surface, suggesting the possibility of cryo-geysers and cryo-volcanoes that are still active

The unusual surprises from the New Horizons spacecraft were not limited to Pluto’s surface, but to its atmosphere as well. Prior to the space mission, Pluto was thought to have a very expansive atmosphere; in fact it was speculated that the atmosphere would be seven to eight times the volume of Pluto itself. Though voluminous it still had a low atmospheric pressure at around one pascal or around 100,000 times less dense than the atmosphere of Earth. 

New Horizons flipped that idea on its head. Instead of a puffy slowly evaporating atmosphere, it has been found that it was instead rather thin, almost hugging the surface of the world. Other gases that have been found are methane and carbon monoxide. Due to the influence of high energy radiation, the carbon monoxide and methane react to form more complex organic compounds such as ethane, ethylene, acetylene, hydrocarbons and hydrogen cyanide. The concentration of hydrogen cyanide was totally unexpected. Temperatures at the surface are around -230 to -210 degrees Celsius. Interestingly enough, due to the methane in the atmosphere there is an actual greenhouse effect at play on Pluto. At thirty kilometers up into the atmosphere the temperature reaches a relatively balmy -163 degrees Celsius. Charon, on the other hand, is somewhat colder than Pluto with an average temperature of -258 degrees Celsius likely due to the lack of any sort of atmosphere.

Another intriguing feature of Pluto’s atmosphere that was discovered by New Horizons is that it possesses a multi-layered haze covering the entire dwarf planet to an altitude of over two hundred kilometers. Even though Pluto has a very low atmospheric density, the haze is appreciable enough to allow for the photography of the “invisible” night side of the dwarf planet, due to the scattering of light by the haze particles. Though not clear as to what the haze particles are, they are probably made up of non-volatiles synthesized from the atmospheric gasses under the influence of cosmic radiation.


New Horizons unfortunately did not stay in the vicinity of Pluto for a long time as its encounter with the dwarf planet was only meant to be a flyby before it ventured in the next decade into the Kuiper Belt and beyond. There is nothing officially being planned for a follow-up to Pluto. However, with all of the exciting and unexpected finds of the New Horizons spacecraft, there are very likely plans of another mission to Pluto being drafted as we speak, to try, probably behind closed doors, to complement the New Horizons historic flight.



References

 




 


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