The Tempest
Non-fiction - by Peter Jekel
There can be no rainbow without a cloud and a storm. J. H. Vincent
When you look up into the night sky, you know that it is there, but you cannot see it – at least if you do not have any optical instruments. Neptune is the farthest planet from the Sun in our solar system since Pluto was relegated to the role of a dwarf planet of the Kuiper Belt in 2006; the Kuiper Belt is a band of icy objects beyond the orbit of Neptune. In keeping with its invisibility to the unaided eye, Neptune is the first planet that was initially discovered by the power of mathematics rather than by direct observation. After the discovery of Uranus in 1781 by Sir William Herschel, French astronomer and mathematician Pierre-Simon Laplace began work on the calculation of Uranus’ orbit in 1783. Fellow French astronomer, Alexis Bouvard subsequently created a set of tables in 1821 showing the orbits of Jupiter, Saturn and Uranus. Something was wrong with the orbit of Uranus. It was not behaving as expected.
In 1843, British astronomer and mathematician, John Couch Adams proposed the idea that the oddities of Uranus’ orbit may be due to an unseen planet and created several estimates of the new planet’s location. In 1845 and independently of Adams, French mathematician Urbain Le Verrier tried to discover mathematically the reason behind Uranus’ misbehavior. On September 23, 1846, German astronomer Johann Galle and Danish astronomer Heinrich Louis D’Arrest-Galle on the eyepiece of the telescope, with D’Arrest reading the charts—discovered the new planet based on the calculations of Le Verrier. In fact, the planet was found only one degree from the area predicted by Le Verrier. Adams’ calculations were found to be twelve degrees beyond the true location of Neptune.
It could be argued that Italian scientist, Galileo, actually was the discoverer of Neptune over 200 years earlier, as he did observe it on December 28, 1612 and again on January 27, 1613. However, due to the fact that Neptune appeared as a “fixed star” and was not recognized as a planet by Galileo, he did not go down in history as the planet’s official discoverer.
Shortly after Galle’s and D’Arrest’s discovery, the planet was named simply as “planet exterior to Uranus” or Le Verrier’s planet. Shortly thereafter, Galle himself suggested the name Janus for the newly discovered planet. Reverend James Challis, a British astronomer whose main claim to fame in astronomy was his inability to discover Neptune in spite of actually having seen it twice in September 1846, mainly due to a lack of diligence on his part, suggested the name Oceanus. Le Verrier felt that since he predicted the location of the new planet that he should be allowed to name it; his suggestion Neptune. However, the name failed to gain immediate traction. Another suggestion from France was to name the new planet Leverrier. Based on what we know of the world today, it could have been called Tempest due to its extremely volatile nature.
The name “Neptune” came to prominence again in later in 1846 when German astronomer Otto Wilhelm von Struve suggested it to the St. Petersburg Academy of Sciences. Now the world was ready for the name and it stuck. The planet would remain the farthest planet from the Sun until the discovery of Pluto in 1930. However, Pluto was demoted to the status of a dwarf planet in 2006 and Neptune reclaimed the crown. Interesting side note: For the period between 1979 and 1999, Neptune, even with Pluto still being recognized as an official planet, was already the furthest planet from the Sun due to the fact that the highly eccentric orbit of Pluto brought it closer to the Sun than Neptune.
Some early science fiction writers took on the opportunity of the newly discovered world to create their tales. In 1900, H. G. Wells wrote of the newly discovered Neptune in his short story, The Star. In the story Neptune’s orbit is altered when a wandering star enters the solar system wreaking havoc. Another early story was Olaf Stapleton’s 1930 epic Last and First Men. Neptune was chosen as the final home of a highly advanced humankind. In spite of their advanced technology, humankind in the story is extinguished when the Sun goes supernova. Today, as an aside, we do know that the Sun is not a massive enough star to go supernova.
When viewed through a telescope, Neptune appears a lot like its neighbouring world Uranus. However, when astronomers began to probe deeper and with observations from the Voyager 2 spacecraft flyby in 1989, they found that though there were similarities there were indeed some profound differences.
At least one science fiction author went beyond the idea of an unmanned probe like Voyager 2 and actually speculated about a manned mission to Neptune but due to technical difficulties, fell short of their ultimate goal. In Hugh Walters’ Nearly Neptune, a fire destroys the essential equipment aboard the space vessel just as they near Neptune.
Perhaps the main difference between Uranus and Neptune is that Neptune is extremely stormy; in fact, it is the stormiest planet in the solar system. Neptune has the wind speed record in the solar system with 2100 kilometers per hour winds being recorded. Kind of frightening when we consider that the most powerful tornadic storms on Earth rarely exceed wind speeds of 320 kilometers per hour. On Jupiter, another stormy planet, the wind speeds can reach up to 550 kilometers per hour—well short of Neptune’s intensity.
The planet also shows evidence of intense storm activity. In 1989, Voyager 2 found that the southern hemisphere had a storm system similar to the Great Red Spot on Jupiter. It was dubbed the Great Dark Spot. The Great Dark Spot disappeared five years later according to observations with the Hubble Space Telescope. However, scientists were able to find a new similar storm system in the northern hemisphere.
Other smaller storms were also discovered on Neptune by Voyager 2. “Scooter” which was a fast-moving system south of the Great Dark Spot. It acquired its name because it moved faster than the Great Dark Spot. Below “Scooter”, there was a Small Dark Spot, another storm in the southern hemisphere that later had disappeared in 1994 when the planet was observed again with the Hubble Space Telescope.
Why should Neptune be so volatile in its weather patterns? There are some obvious reasons for the high winds of Neptune, of course, such as the fact that as the size of a planet increases the greater its angular momentum…which translates into higher atmospheric movement—though Neptune is the smallest of the gas giants, at around seventeen times as large as the Earth. Its relatively short sixteen-hour days also contribute to higher wind speeds as the faster that a planet rotates, the faster the atmospheric turbulence. Low atmospheric temperatures also contribute to higher wind speeds as it reduces the viscosity of the gases that make up the atmosphere.
However, the known factors alone will not create the conditions being observed on Neptune. There has to be another variable. The likely explanation is the high internal heat of Neptune. This, interestingly enough, has been hypothesized to be due to the fact that the planet is still forming and collapsing inward, thus creating the excess heat. In fact, Neptune radiates over two and a half times as much energy as it receives from the Sun.
The atmosphere that feeds these enormous winds is made up predominately of hydrogen and helium with some methane. The methane of the atmosphere gives the planet its bluish colour, as methane absorbs the red of the visible light spectrum. As we venture further up into the atmosphere, the stratosphere, we find more and more complex hydrocarbons such as ethane and acetylene, probably created due to the reaction of methane with ultraviolet light. It is the higher presence of hydrocarbons in the stratosphere that gives Neptune a higher atmospheric temperature (average of -218 degrees Celsius) than its neighbor, Uranus (-224 degrees Celsius), which is actually significantly closer to the Sun with an average distance of 2.88 billion kilometers compared with Neptune’s average of 4.55 billion kilometers.
Another unusual observation of Neptune’s atmosphere in 2007 showed that the planet had a ‘relative’ hot spot at the south pole. ‘Relative,’ because it was only ten degrees Celsius higher than the rest of the planet. The most likely explanation for the hot spot is that the south pole has been tilted towards the Sun for the past forty Earth years, a quarter of a Neptune year, the equivalent of 164.79 Earth years. As the planet continues its travels around the Sun, the ‘hot spot’ will shift to the north pole. This ‘hot spot’ provides a system for the escape of methane deep in the atmosphere into the planet’s upper reaches. Research suggests the frequent release of methane into the atmosphere could result in diamond rainfalls.
Neptune, like the other gaseous planets, has a faint ring system. The first astronomer to mention them was English astronomer William Lassell (discoverer of the moon Triton in orbit around Neptune) in 1846. Unfortunately for Lassell, his observation could not be subsequently substantiated and was considered to be nothing more than an observational problem. In 1968, during a stellar occultation, astrophysicist Edward Guinan and his team at Vallanova University near Philadelphia, appeared to have discovered the first ring; however, when Voyager 2 made its flyby in 1989, it was found that the “ring” discovered by Guinan was actually the moon, Larissa. It was through the observations of Voyager 2, though, that Lassell was still vindicated. Neptune did indeed have a ring system.
Altogether there are six known rings: Galle, Le Verrier, Lassell, Arago and Adams along with a faint, sixth, unnamed ring. The rings consist of micrometer-sized dust particles made up of a mixture of ices and organic chemicals which give the rings a somewhat reddish tinge. Three of the rings are quite narrow—under one hundred kilometers in width. The other two, Galle and Lassell, are quite extensive, reaching widths of 2,000 to 5,000 kilometers. They are quite young and are hypothesized as being sourced by the destruction of a moon of Neptune when it wandered too close to the gravity well of the larger planet.
Interestingly enough, Alastair Reynolds wrote of this very idea in his short story, “Vainglory.” In the story, he describes the formation of Neptune’s ring system after the deliberate destruction of one of the planet’s moons, Naiad.
It is the outermost ring, the Adams ring, is actually the most interesting. It consists of a continuous ring embedded with five brighter arcs. The arcs are areas where the material appears to clump, all in apparent violation of any physical laws of nature. Currently, scientists are unable to explain the oddity, but one theory is that it may have something to do with an interaction with nearby moons of Neptune. Further work has to be done.
Neptune, like the other gas giants and the planet Earth, possesses a magnetic field and like Uranus, is strangely oriented to the rotational axis of 47 degrees. When scientists saw an unusual orientation of the magnetic field, they had to come up with a new theory to explain it. It is hypothesized that the dynamo that creates the magnetic field must be much closer to the surface of the planet than that of Earth, Jupiter and Saturn.
Not much is known about the interior structure of Neptune directly. Most of the theories about come from inferences made based on the planet’s radius, mass, rotation period, and the shape of the gravitational field. Below the atmosphere there is theorized to be an ice mantle rich in water, ammonia and methane. There may be a water-ammonia ocean. Deeper yet and due to the high pressures, there may be a superionic ocean where the oxygen may actually have crystallized into a mixture of hydrogen ions that float freely in the oxygen lattice work. If we venture deeper down still to around 7,000 kilometers, the methane there will be crushed into diamond crystals. The core of the planet is thought to be made of iron, nickel and silicate rock, slightly larger than the Earth.
At least one author, Mike Resnick, wrote about the possibility of life on Neptune, but suffice it to say, that in spite of being nominated for a Hugo and Nebula Award, it really was not meant to be taken seriously. The title of the science fiction comedy story is Elephants on Neptune. Simply put, the story is just about that, elephants on Neptune. Ben Bova’s posthumously published Neptune, part of his Grand Tour series, also explored the possibility of life on Neptune as well as its moons, but with a more serious spin to it.
As interesting as Neptune may be, it is one of its moons that intrigues scientists and science fiction writers alike. Neptune has fourteen known moons with one moon comprising almost 100% of the mass of the objects orbiting Neptune. That moon is Triton. Triton is even larger than the former planet, Pluto, with a diameter of 2710 kilometers.
It was discovered only seventeen days after the discovery of Neptune by English astronomer William Lassell. Since the moon has a retrograde orbit, the only moon in the solar system to do so, it is theorized that the moon was a capture from the rocks of the Kuiper Belt. Its spheroidal shape also adds to the evidence that it is a Kuiper Belt capture. In 1989, it was found that Triton has the record for being the coldest place in the solar system at a temperature -235 degrees Celsius.
Triton’s surface is mostly covered by frozen nitrogen, water and carbon dioxide. Other surface ices include methane and carbon monoxide. The ice’s red colour is thought to be the result of methane ice that is converted to tholins under bombardment from ultraviolet radiation from the sun. Tholins are molecules created out of simple organic molecules such as carbon dioxide, methane and ethane as well as nitrogen into complex organic molecules through interaction with ultraviolet or even higher energy radiation.
When Voyager 2 ventured by the moon, it found evidence of geyser-like eruptions that erupted nitrogen gas and dust from the interior of Triton; all the geyser activity takes place in the southern hemisphere between fifty and fifty-seven degrees latitude. Some of these eruptions can last up to a year and carry dust up to 150 kilometers from the source. The scarcity of craters on Triton suggests that the geological activity on the moon is still happening. There are also a number of ridges and valleys on Triton which appear to be the combination of freeze-thaw slip cycles combined with tectonic activity.
Further evidence of a geologically active surface on Triton includes a cantaloupe-like terrain in the western hemisphere. The depressions are up to thirty and forty kilometers in diameter. Their consistent size and smooth curves indicate that they are not impact craters, but something else. One idea is that they are the result of diapirism where lumps of less dense material push upwards through a layer of denser material such as rock.
Adding to the unusual nature of Triton is that fact that it contains a tenuous atmosphere, one of the few moons in our solar system to have one. Most of the atmosphere is made up of nitrogen along with some carbon monoxide and methane near the surface. Granted, it is very rarified, possessing a pressure of only 1/70,000 that of the pressure on Earth at sea level. In 1997, however, Earthbound observations seem to indicate that the moon may have a slightly denser atmosphere than was originally predicted from data provided by Voyager 2.
Triton has obviously stimulated the imaginations of science fiction authors far more than the parent planet. Some authors have seen the moon as a possible site for human colonization. In Samuel Delany’s novel, Triton, humans have colonized much of the solar system, including the moon Triton. Piers Anthony, in his novel, Macroscope, the protagonists terraform an area on the moon for settlement.
Other authors have looked at the moon as a site for ancient astronauts. In Christopher McKitterick’s Transcendence, one of the storylines takes place on the moon of Triton where an alien artifact has been found. Jeffrey Carver, in his Neptune Crossing, a pilot explores the moon, only to fall through the ice where he discovers an ancient alien artifact, and there becomes host to one of the aliens that existed on the moon at one time. Gordon Eklund’s novel, A Thunder on Neptune, is a tale of the exploration of Neptune and Triton which includes the discovery of a life form on Neptune.
Neptune has another moon, Nereid, that appears to have captured the interest of at least one science fiction writer. Nereid is the third largest moon of Neptune and was discovered in 1949 by American astronomer Gerard Kuiper. Like Triton, it was probably a captured body of the Kuiper Belt. Larry Niven, in his novel, Ringworld, describes an Outsider settlement on Nereid; Outsiders are alien many-limbed aliens called cat o’ nine tails.
When the planet Neptune was discovered, it truly proved the power of mathematics in astronomy. Unfortunately, mathematics only allowed us to find this needle in a haystack. From the exploration of the world by astronomers and the Voyager 2 spacecraft, we found more and more about the world and its moons. We found a world that was stranger than anything that mathematics could have predicted and even now we still are looking for answers to explain the data. NASA had at one time proposed the Neptune Orbiter that was to be launched in 2016, which would have answered our many questions about the planet. Unfortunately, the project was shelved. There is hope, however, on the horizon, as there is still a project that was first proposed in 2015 by NASA, the Triton Hopper, that is still in the planning stage. Let us hope that this project stays viable.
Shakespeare’s play The Tempest has been classified as the best of all of his works, in addition to being his last. It is a play full of mystery and magic, not unlike the world that truly could bear the same name, the world that awaits us at the outer reaches of the solar system.
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