Keep the shuttle flying: Fwd: he Strange Discovery of Planet X and a World Like No Other

Sent from my iPad

Begin forwarded message:

From: "Gary Johnson" <gjohnson144@comcast.net>
Date: June 7, 2015 at 9:50:44 PM CDT
To: "Gary Johnson" <gjohnson144@comcast.net>
Subject: FW: he Strange Discovery of Planet X and a World Like No Other - Part 2

AmericaSpace
For a nation that explores
June 6th, 2015
Five Weeks to Pluto: The Strange Discovery of Planet X and a World Like No Other (Part 1)
By Ben Evans

Artist's concept of NASA's New Horizons spacecraft during closest approach to Pluto on July 14. Image Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)
In the dark, outer reaches of the Sun's realm lies a world unlike any other. Discovered in the spring of 1930, Pluto—named by an Oxford schoolgirl, who was fascinated by classical mythology—was for three-quarters of a century considered the ninth planet in the Solar System, before a major reclassification in 2006 demoted it to its present status as a dwarf planet, a trans-Neptunian object and the largest known body in the Kuiper Belt. Since then, it has proven the butt of much cruel humor, with fierce debate on whether it should be reinstated as a "planet" or if it should retain its somewhat less lofty descriptor. Thirty-eight days from now, on 14 July, our final first-time, close-up glimpse of the last of the "classical" nine planets will be made, as New Horizons reaches the climax of its 9.5-year voyage. Over the coming weeks, AmericaSpace's New Horizons Tracker and a series of articles by Mike Killian, Leonidas Papadopoulos and myself will cover the discovery and exploration of Pluto to date, the many trials and troubles faced by those who desired to send a spacecraft there and the unfolding developments as New Horizons seeks to make this unknown world known.
For many of us, born and raised long before 2006, it was simple and taught through nursery rhymes and schooltime songs: Pluto was the ninth planet in the Solar System, although it was known that the dynamics of its highly elliptical orbit—which carries it out of the ecliptic, the plane on which the other major planets circle the Sun—caused it to periodically draw closer to its parent star than Neptune, moving into eighth place for a while, then receding back to ninth. And since the dawn of the Space Age, humanity has long desired to visit each of these worlds, which had hitherto appeared as little more than points of light in telescope eyepieces. Mercury, the innermost planet to the Sun, was first imaged by Mariner 10 during a pair of flybys in March and September 1974; Venus by Mariner 2 in December 1962; Mars by Mariner 4 in July 1965; Jupiter by Pioneer 10 in December 1973; Saturn by Pioneer 11 in September 1979; and Uranus and Neptune, both by Voyager 2, in January 1986 and August 1989. And now, in the summer of 2015, New Horizons will pass and observe Pluto for the very first time.
Whichever way one looks at it—whether you believe Pluto to be a planet or not—our first visit by a machine fashioned by human hands promises to be an epochal moment in the history of our species; an illustrator of how far we have come, figuratively and literally, in just a handful of decades. Yet the discovery of tiny Pluto came about through a peculiar set of circumstances, influenced by the unexpected motions of its far larger sibling, Neptune. Discovered in September 1846, it soon became clear that Neptune did not appear to follow its predicted orbital path, even after experts in celestial mechanics had taken the combined motions and perturbations of the other planets into account. In the early part of the last century, the U.S. astronomer Percival Lowell tasked himself with finding an unseen "Planet X", a new world beyond Neptune, and it is an unfortunate footnote of history that the man who founded the Lowell Observatory in Flagstaff, Ariz., and proclaimed that artificial canals existed on Mars never realized how close he came to finding Pluto.
Percival Lowell, pictured in 1914 observing Venus. It was during these last two years of his life that he attempted to find Planet X…and almost succeeded. Photo Credit: Wikipedia
Lowell conducted several telescopic and photographic searches of the heavens from 1905 onwards, all within the level of the Solar System's ecliptic plane and all without success, but a few years later he happened to attend a lecture by his friend, William Pickering of Harvard University, who described a graphical plot of the motion of Uranus as a predictor of a trans-Neptunian planet. Pickering nicknamed the hypothetical object "Planet O" and speculated that it might lie 52 Astronomical Units (AU)—about 5 billion miles (8 billion km)—from the Sun and take 373 Earth-years to accomplish a full revolution of its parent star. Drawing on Pickering's theory, Lowell refined his own calculations and by 1909 was in a position to predict with reasonable confidence that an unknown planet lay 47.5 AU, or 4.4 billion miles (7.1 billion km), from the Sun and took 327 Earth-years to complete an orbit. He also suggested that it was less than half as massive as Neptune itself.
Lowell understood that Neptune, discovered just a few decades earlier, had simply not been observed for long enough in its 165-Earth-year orbit for full perturbations of its motion by another planet to be readily apparent. As a result, he relied upon the smaller and less obvious perturbations on Uranus—discovered in 1781 and whose 84-Earth-year orbit had therefore been fully observed during at least revolution of the Sun by Lowell's time—to assist with his calculations. In July 1910, Lowell started a second telescopic search for Planet X, whilst in tandem Pickering published estimates for three more trans-Neptunian objects, which he labeled "P", "Q" and "R". Unfortunately for Pickering, his prediction that Planet Q was 20,000 times more massive than Earth drew much scorn and criticism from his contemporaries. Sadly, his prediction of where Planet O may reside actually turned out to be tantalizingly close to where Pluto was ultimately found in February 1930.
As for Lowell, he spent the remaining years of his life, until his death in 1916, searching without success for the mysterious new world. He labored under the assumption that Planet X carried a mass seven times larger than Earth—approximately half as massive as Neptune—and took the form of a low-density object with a high albedo, similar to the giant gaseous planets and revealing an easily visible disk with a diameter of one arc-second and an apparent magnitude of 12-13. During his endeavors, he identified 515 asteroids, 700 variable stars and—without realizing—in March 1915, two of his photographic plates revealed a faint object, somewhere between 15th and 16th magnitude, which later turned out to be Pluto. With the benefit of hindsight, it seems unlikely that Lowell even looked at the two plates, for the faint object was far dimmer than anything like the kind of magnitude he expected for Planet X. His brother, George, subsequently wrote with a hint of sadness: "That X was not found was the sharpest disappointment of his life".
Thirteen years after Lowell's death, in January 1929, a 22-year-old Kansan farmboy named Clyde Tombaugh joined the staff of the Lowell Observatory. He had no formal training in astronomy, but had so impressed the observatory's director, Dr. Vesto Slipher, with his remarkable sketches of Mars and Jupiter that he was offered a job. Tombaugh's first assignment was to search for Planet X and, to achieve this end, he utilized the Lowell Observatory's 13-inch (33 cm) telescope to acquire 14 x 17-inch (35 x 43 cm) photographic plates by night, in tandem with a "blink comparator". The latter alternately shone a light through one plate, then another, so that any object which appeared in both plates—like an apparently motionless star—would appear steady and unmoving. On the other hand, if an object turned up on one plate, but not the other, or in different places on both plates, it would "blink" noticeably.
Clyde Tombaugh, an American astronomer who discovered Pluto in 1930. Photo Credit: AP
By thus enabling Tombaugh to flip backwards and forwards betwixt plates, the effect was akin to perusing a picture-book and carried obvious benefits for finding a new planet, which would be expected to "move" against a seemingly stationary backdrop of stars. Significantly, he focused on the entire zodiac, rather than the regions suggested by Lowell, and over the course of his first year at the observatory he observed almost two million stars, before reaching the constellation of Gemini. His attention was drawn to a pair of photographic plates taken six days apart, on 23 and 29 January 1930, which revealed a faint speck, moving gradually across the sky, close to the star Delta Geminorum. A third plate, of somewhat lesser quality, served as confirmation of the new planet's motion. "On 18 February 1930, I suddenly came upon the images of Pluto," Tombaugh later wrote. "The experience was an intense thrill, because the nature of the object was apparent at first sight."
He walked straight into Slipher's office with the news. "Doctor Slipher," he announced triumphantly, as described by Ken Croswell in Planet Quest: The Epic Discovery of Alien Solar Systems, "I have found your Planet X!" It lay just six degrees from one of two locations suggested by Lowell. After several more nights of observations, the discovery was verified and on 13 March—what would have been Percival Lowell's 75th birthday—it was telegraphed to the Harvard College Observatory (HCO) at Harvard University in Cambridge, Mass., and formally announced to the world.
In spite of the euphoria, the diminutive new world was far from what had been anticipated by Lowell, Slipher, Tombaugh and the bulk of the astronomical community who fervently believed in the existence of Planet X. Occupying a highly elliptical orbit, which carries it out of the ecliptic plane, ranging as close as 30 AU (2.7 billion miles or 4.4 billion km) and as far as 49 AU (4.6 billion miles or 7.4 billion km) from the Sun, Pluto proved so tiny and so dark that it revealed no visible disc and was six times dimmer than Lowell had predicted. Right from the outset, it had a tough time earning scientific recognition as a fully fledged "planet". The German-born U.S. astronomer Armin Leuschner suggested as early as 1932 that its dimness and high orbital eccentricity made it more likely to be an asteroid, its course severely perturbed by a close passage to Jupiter, or even a long-period comet, whilst others published mathematical presumptions that irregularities in Uranus' orbital motion were probably not induced by a mysterious outer planet after all.
Notwithstanding its nature, the discovery of the new world prompted the search for a name. And not just any name, for it resided further from the Sun than any other known planet in the Solar System, in a dark and gloomy realm, where incident sunlight was the tiniest fraction of the quantity that we receive on Earth. It was this location, this darkness and this gloom, which led to the name "Pluto" being suggested: though not by a panel of academics, but, as will be described in tomorrow's AmericaSpace article, by an 11-year-old schoolgirl from the English city of Oxford.

Copyright © 2015 AmericaSpace - All Rights Reserved

AmericaSpace
For a nation that explores
June 7th, 2015
Five Weeks to Pluto: The Strange Discovery of Planet X and a World Like No Other (Part 2)
By Ben Evans

A computer-generated impression of the view from the surface of Pluto. The Sun looks like a very bright star on the sky (upper right), while Charon, Pluto's biggest satellite looms large near the horizon (at left). NASA's New Horizons mission will replace our artistic impressions of the planet and its moons with real high-resolution images of their landscapes. Image Credit: ESO/L. Calçada
Thirty-seven days from now, on 14 July, NASA's New Horizons spacecraft will sweep past the dwarf planet Pluto, its large companion Charon, and a system of at least four tiny moons, as it reaches the climax of a 9.5-year voyage to unveil a group of the Solar System's farthest known celestial bodies. In doing so, as described in yesterday's AmericaSpace article, it will bring full-circle our first-time exploration of each of the traditionally accepted nine planets in the Sun's realm. Although Pluto was demoted back in 2006 to the status of a dwarf planet, a trans-Neptunian object, and the largest known body in the Kuiper Belt, and has proven the butt of much cruel humor, fierce debate still exists on whether it should be reinstated as a fully fledged "planet" or if it should retain its somewhat less lofty descriptor. Over the coming days and weeks, AmericaSpace's New Horizons Tracker and a series of articles by Mike Killian, Leonidas Papadopoulos, and myself will cover the discovery and exploration of Pluto to date, the many trials and troubles faced by those who desired to send a spacecraft there, and the unfolding developments as New Horizons seeks to make this unknown world known.
Following confirmation of the new world's discovery on 13 March 1930, the news spread across the world. Reading of the discovery in The Times on 14 March, whilst sat at breakfast table in a well-to-do dining room in Oxford, England, was retired Bodleian librarian Falconer Madan and his 11-year-old granddaughter, Venetia Burney. The young girl had been learning about classical mythology at school and suggested to her grandfather that the new world should be named "Pluto," after the ancient Roman god of the underworld. "I was quite interested in Greek and Roman myths and legends at the time," she explained in a January 2006 interview for the BBC, adding that astronomy also left an indelible mark on her. "At school, we used to play games … putting lumps of clay at the right distance from each other to represent the distances of the planets from the Sun. Some of the distances I can still more or less remember, so it was probably a good lesson to have had."
Venerated by the ancients as a stern and violent ruler, Pluto's original Classical Greek name was "Plouton" and today he is associated as the overlord of Hades, the chthonic land of the dead, to which the souls of the departed were ferried across the River Styx by the mysterious boatman, Charon. His name was subsequently Latinized to "Pluto" by the Romans, producing the current form of the name. He is perhaps best known as the husband of Persephone, whom he abducted from her mother, the goddess Demeter, and later forced to spend a third of each year with him in the dark, gloomy underworld, receiving the souls of the dead and dispensing judgment upon them.
Venetia Burney as a child, pictured at around the time that she chose the name for Pluto. Photo Credit: Wikipedia
Lying so far from the Sun, in such a dark and gloomy region of the Solar System, to Venetia Burney, "Pluto" was thus the ideal name for the new world. Her grandfather was so impressed that he contacted his friend, Prof. Herbert Hall Turner, director of the University of Oxford's observatory, who coincidentally happened to be at a meeting of the Royal Astronomical Society (RAS) in London, debating a name. "It was incredibly lucky in a number of ways," Burney—who subsequently became a teacher of mathematics and economics, married, and became Venetia Phair—explained in later life. "Firstly, I was lucky in having a grandfather who pursued the matter and knew Prof. Turner. And it is extremely lucky that the name was there. There were practically no names left from classical mythology. Whether I thought about the dark and gloomy Hades, I'm not sure."
For his part, Falconer Madan dropped a note off at Prof. Turner's house during one of his regular visits to the Bodleian Library. In Turner's mind, all of the names considered to date—which included Minerva, Zeus, Atlas, and Persephone—seemed unsuitable for the new world, with "Cronus" briefly considered a possibility, but dismissed as it was actually the Greek equivalent of Saturn. "I think Pluto is excellent," Turner later wrote to Falconer Madan. "We did not manage to think of anything so good at the RAS." He sent a telegram to his colleagues at the Lowell Observatory. "Naming new planet," he advised them, "please consider Pluto, suggested by small girl Venetia Burney for dark and gloomy planet." It was saddeningly fortuitous that Turner wrote when he did, for he passed away suddenly from a haemorrhage in August 1930.
On 1 May 1930, it was official and the new planet was named Pluto, decisively beating the other two finalists, Cronus and Minerva. Although it was generally well received, there were several individuals who disliked it, particularly Charles Freedom, superintendent of the U.S. Naval Observatory in Washington, D.C., who regarded it as "the prototype of Satan in many minds." Others paid tribute to the fact that the name's first two letters honored Percival Lowell, the man who had come so close to find the planet in his exhaustive searches. Even Lowell's friend, William Pickering, was fond of the name, joking that its first two letters offered a nod to his own and Lowell's calculations, as "Pickering-Lowell." For her part, Venetia Burney received a substantial reward of £5 from her grandfather—"he liked to have an excuse for generosity"—and passed blissfully into obscurity, re-emerging periodically into the limelight whenever "her" planet made the news.
Invited by NASA in January 2006 to attend New Horizons' launch from Cape Canaveral Air Force Station, Fla., she was forced to decline, on account of her advancing age. However, in June of that year, NASA announced that it had named New Horizons' student-built dust counter as "Venetia." "I feel quite astonished, and to have an instrument named after me is an honor," the 87-year-old retired teacher commented at the time. "I never dreamed when I was 11 that, after all these years, people would still be thinking about this and even sending a probe to Pluto. It's remarkable." In making the announcement, Dr. Alan Stern, New Horizons' Principal Investigator, commented that it was "fitting" that one of the spacecraft's should honor "her historic, early role in the saga of the ninth planet." She died in 2009.
Artist's conception of Pluto and Charon. Image Credit: ESO
In the decades after Pluto's discovery, significant reassessments were made about the new world, as its estimated size and mass continued to progress in a downward direction. At first, it was suspected to be about the same equatorial diameter as Earth, but 1949 observations by Gerard Kuiper, using the 200-inch (510-cm) telescope at Mount Palomar Observatory, operated by the California Institute of Technology in San Diego County, Calif., led him to the conclusion that it was sized midway between Mercury and Mars, with a mass about a tenth of Earth. However, even with such large astronomical instruments, it was difficult until as late as the 1970s to discern any significant detail about Pluto, other than a rotation rate of about 6.4 Earth-days and a handful of details about the nature of its highly elliptical orbit.
That situation began to change in 1976, when frozen methane was spectroscopically detected on the planet's surface by Dale Cruikshank, Carl Pilcher, and David Morrison of the University of Hawaii at Honolulu. Their work marked the first occasion that anything other than water ice or frozen carbon dioxide had been discovered spectroscopically, anywhere in the Solar System, and the presence of frozen methane implied that Pluto's surface must be highly reflective. Following this line of discussion further, the measured brightness and its known distance from Earth and the Sun suggested that Pluto must be about 0.01 Earth-masses, far smaller than previously supposed and smaller even than our Moon. Similar conclusions had earlier been reached by Dennis Rawlins, who measured albedo variations between Pluto and Neptune's large moon, Triton, and suggested that both bodies were of similar mass.
Two years later, in June 1978, U.S. Naval Observatory astronomer James Christy was in the process of examining an enlarged photographic plate of Pluto from April 1965, in tandem with more recent images from the 61-inch (1.5-meter) telescope at U.S. Naval Observatory Flagstaff Station (NOFS). He spotted a noticeable "bulge" apparently emanating from one side of the planet's disk. At first, it was supposed that the anomaly represented a default in the image, caused by improper alignment, and this suspicion endured for more than a decade. However, upon closer examination, Christy noticed that only Pluto itself appeared elongated in the image and he concluded the presence of a large attendant moon.
It remained possible, of course, that the distortion might be due to Pluto having an irregular shape, but subsequent mutual eclipses of the two bodies on five occasions between 1985-1990 confirmed the existence of the moon, which was named "Charon," after the boatman who ferried the souls of the dead across the River Styx to Hades. Despite being originally pronounced in Latin in a similar fashion to "Karen," the name also proved helpful to Christy himself, whose wife, Charlene, was nicknamed "Char." Yet the name was perfectly in harmony with Pluto itself. In ancient times, a coin—known as "Charon's obol"—was traditionally placed onto the tongue of a dead person, in order to pay the boatman for his service in conveying the soul across to Hades and into Pluto's realm.
Artist's concept of the New Horizons spacecraft during its planned encounter with Pluto and its moon, Charon. Image Credit: NASA
In the years after Charon's discovery, estimates were made by Robert Harrington of its orbit and the mass of Pluto itself; in effect, the moon had provided a significant breakthrough in our understanding of the ninth planet. The result confirmed that Pluto is about a fifth as massive as our Moon, thus nowhere near sufficient to have perturbed Uranus' or Neptune's orbits. Moreover, its relationship with Charon was less of a host-satellite one, and more of a "binary-planet." Charon orbits about 11,700 miles (18,800 km) from Pluto's surface, circling every 6.4 Earth-days, exactly matching the rotation rate of its larger partner. In the same manner as our Moon, Charon keeps the same face directed toward Pluto in perpetuity. However, unlike our planet, which spins 29.5 times for each lunar cycle, one side of Pluto always faces Charon and vice versa. An observer on Pluto's Charon-facing side would see the moon hanging in the sky, unchanging its position over the years, whilst an observer on the planet's space-facing side would not even know that his world possessed a moon.
Surprisingly, Charon's north-south motion—indicative of the fact that the pole of its orbit resides within the plane of the ecliptic—provided clear evidence that Pluto's own rotational axis was tipped very closely to the ecliptic, in a similar fashion to Uranus. It soon became apparent that Charon's orbital plane would be seen edge-on from Earth in the mid-1980s and proved extremely fortunate in terms of timing, for these mutual eclipses occur only twice in Pluto's 248-Earth-year orbit of the Sun. "We immediately appreciated our good fortune," explained Cruikshank in a chapter on Pluto, Triton and Charon for the fourth edition of The New Solar System. "Had Charon been discovered in, say, 1993, we would had to wait until the 22nd century to witness the next series of overlappings." The alignments enabled astronomers to spectroscopically monitor the faint emissions from the system, revealing an approximate diameter for Pluto about two-thirds the size of our Moon.
The combined density of the two worlds suggested a composition of 60-70 percent rocky materials, with 30-40 percent ices. Moreover, the rotational locking of the two worlds was suggestive of Charon being a large body, relative to its host, and celestial dynamicists have suggested that the size ratio between the two is closer than any other host-satellite pairing in the Solar System. Present estimates show Charon to be a little more than half the size of its host, with an equatorial diameter of about 750 miles (1,200 km), compared to Pluto's 1,470 miles (2,370 km). Spectroscopy has also revealed Pluto to be predominantly coated with ices of nitrogen and methane. This can be compared to less volatile water ices in the case of Charon, with patches of ammonia hydrates and water crystals detected in 2007, suggesting the possible presence of active cryovolcanism or cryogeysers, perhaps not dissimilar to those observed on Neptune's moon, Triton. Current thinking suggests that Charon's overwhelmingly icy composition may indicate that it was formed as a consequence of a giant impact into Pluto's icy mantle.
As will be explored in next weekend's series of Pluto and New Horizons articles, Hubble Space Telescope (HST) and advanced ground-based imagery over the past two decades has revealed significant inroads into our understanding of this strange system and, until mid-May 2015, these observations were the most comprehensive in our possession. As New Horizons draws closer to its date with destiny on 14 July, many of the questions surrounding both Pluto and Charon—and four other, smaller moons, named Nix, Kerboros, Hydra, and Styx, discovered between 2005-2012—will hopefully be resolved, as well as undoubtedly inspiring new questions.

Copyright © 2015 AmericaSpace - All Rights Reserved