Chapter 6 The Invention of the Telescope: “Magic Tubes” Children invented the telescope! Playing with the discarded lenses the children of a spectacle maker placed two lenses one in front of the other and saw a nest in a belfry some distance away and they excitedly showed their father who then proceeded to make the first telescope. At least that’s one of the stories surrounding the sudden appearance the device in 1608 that would be the pivotal instrument of modern astronomy. Like most urban legends, this story is impossible to verify and is probably not true, but it is a good story and everybody likes a good story. It is certainly better than having some individual noticed this particular property of lenses then figured or experimented with different combinations to get the magnification without the inversion and placed them in a tube with the ability to focus. No one really knows who invented the telescope. The device first appeared in Holland and quickly spread throughout Europe, being marketed as “Magic Tubes,” in 1608. Hans Lippershey of Middelburg was the first to apply for a patent. Jacob Metius of Alkmaar also applied for a patent for “seeing faraway things as though they were nearby.” The States General (the national government) in Hague discussed the patent applications of both. The device consisted of a combination of a convex and a concave lenses in a tube with a magnification power of 3 or 4 times. The agency denied awarding the patent to either applicant, not because they considered it a bad idea, but because it was so easy to copy and so widespread; it could not be protected. The agency awarded Metius a small stipend for his efforts and commissioned Lippershey to build several binocular versions for which he was paid very well. The Concept Behind the Telescope The concept behind the telescope is rather simple and the technology needed to build one had already existed for a millennia before the first telescope was built in 1608. The telescope is based on the innate property of the lens to refract light, that is, change its direction and actually project an image. If you take any large magnifying glass any hold it parallel close to a wall, you will see an image cast on the wall. It is inverted and a bit distorted, but it is a real image of what ever is reflecting the light. This is the basis on which your eye and the camera work. If you raise the same magnifying to see a distant object you will see an inverted image of the object. You may have to adjust the distance of the magnifying glass to your eye to bring this into sharp focus, but there is no magnification just an inverted image. However if you get a second, smaller magnifying glass (shorter focal length) and align in front of the first then you will see a magnified inverted image. The amount of magnification depends on the ratio of the focal lengths of respective magnifying glasses. This is basic concept of the refracting telescope. Galileo and the Telescope

Galileo Galilei was the first to use the Dutch invention to systematically observe celestial bodies and record his observations. Taking the basic design, that is a convex objective lens and a concave eyepiece and improved on it making more suitable for astronomical observations. He made it with greater magnifying power by having a larger objective lens with a longer focal length and an eyepiece with a shorter focal length. He eventually made a telescope about 20X magnification. The magnifying power of a telescope is calculated by dividing the

focal length of the objective lens by the focal length of the ocular lens. For example if the focal length of the objective lens is 30 inches and focal length of the eyepiece lens is 1 inch the power in

this instance would be 30X. There were two main factors limiting the meaningful magnification of a telescope; the size of the objective lens, which determines the amount of light gathered and the minimum size of the eyepiece that can be reasonably seen by the human eye. In perfect viewing conditions, magnification is limited to about 60 X per inch of the objective lens. Galilean Telescopes A typical Galilean telescope was configured with a plano-convex objective (the lens toward the object) with a focal length of about 30-40 inches., and a plano-concave ocular with a focal length of about 2 inches. The ocular was in a little tube that could be adjusted for focusing. The objective lens was stopped down to an aperture of 0.5 to 1 inch and the field of view was about 15 arc-minutes. The instrument's magnification was 15-20 power. Even the finest glass was full of little bubbles and had a greenish tinge (caused by the iron content of the glass); the shape of the lenses was reasonable good near their centers but poor near the periphery (hence the restricted aperture); the polish was rather poor. The limiting factor of this type of instrument was its small field of view--about 15 arc-minutes--meaning that only a quarter of the full Moon could be accommodated in the field. Over the next several decades, lens-grinding and polishing techniques improved gradually, as a specialized craft of telescope makers slowly developed. But although Galilean telescopes of higher magnifications were certainly made, they were almost useless because of the concomitant shrinking of the field. Galileo and the Moon Galileo’s observations of the moon with a telescope gave an eloquent explanation for the “spots” on the moon and ravaged the long held perception of the perfection of the universe. In that hypothesis the moon had to be a perfect sphere and smooth.

Figure 21 Typical Galilean telescope with mount 1609

Figure 20 Galileo Galilei 1564-1642

The moon is the only celestial body that has features discerned by the human “naked” eye. These “spots” presented a problem for Aristotle whose philosophy exhorted the perfection of the universe but the “spots” existed and they were permanent. He finally conceded that perhaps “corruption” from the earth had contaminated the moon. Other explanations were offered (the moon was a mirror and the spots were a reflection of something, that the moon had different densities and thus different reflective qualities) but Galileo had dashed all of these. The moon was not smooth. It was pitted with mountains, depressions, craters and valleys. His analysis of the observations were extensive and his conclusions accurate. He clearly explained the reasons for the phases of the moon and the relationship with the earth. From the moon the earth would also display all the phases from “new earth” to “full earth,” and further at new moon, you would see “full earth.” Galileo and the Phases of Venus When Galileo turned his telescope Venus he knew that that the Copernicus’ model of the solar system was correct even if the parallax predicted by the model could not be detected. The phases of Venus could only be explained by the planet orbiting the Sun, not the earth. The universe was simply a lot bigger than what they had conceived. Discovery of Jupiter’s Moons In January 1610, Galileo made a series observations of Jupiter making a discovery that shook the world and assaulted mankind’s ego. Every thing did not revolve around the earth. Besides providing another clue that indeed the earth was not the center of the universe. It destroyed the prevailing concept of gravity; that everything fell to the earth. Galileo initially named the four moons of Jupiter ‘Medicean Stars,’ but in the later named his discovery Cosmica Sidera (“Cosimo’s Stars”) however the prevailing names (Io, Europa, Ganymede and Callisto) were chosen by a contemporary, Simon Marius who also claimed to have discovered the moons of Jupiter. This led to a dispute with Galileo

Figure 22. Galileo’s sketch of the sidereal moon

accusing him of plagiarism. Of course, Simon Marius, a German astronomer, took umbrage at the accusation in a dispute that was not settled until long after both were dead. In 2003 a jury in The Netherlands examined the evidence extensively and ruled in favor of Marius’ independent discovery of the moons. After converting the date on Marius’ observation in the Julian calendar to the Gregorian calendar, Marius staring taking notes on the observation one day later than Galileo. Simon Marius and Galileo, both very competitive, like most of the scientists of the time, never reconciled each fiercely protective of their work and deprecating of their rivals. Marius commented that Galileo really didn’t invent the telescope, which, of course was true. Galileo never claimed to be the inventor of the instrument. He just improved it and used it very well. Kepler suggested the mythological names Marius used for the moons. Galileo and Mars Through his telescope Galileo saw Mars as a simple disk without any features yet over a period of time of careful observations he was able to discover the nature of Mars’ mysterious orbit. Mars is indeed orbiting around a fixed point but it was the sun not the earth. In the Ptolemaic system, Mars’ retrograde motion was handled with epicycles but the cyclical brightening and dimming of the planet remained a mystery. With his telescope, Galileo was able estimate the change in size of Mars and from there calculate distance. The dimming and brightening was due the change in distance from the earth. Both, the retrograde motion and the change in brightness of the planet were explained by the Copernican solar system theory. Galileo and the Mysterious Planet When Galileo first turned his attention to the furthest known planet, as a tri-planet system. He drew it as a big circle with two smaller circles on either side almost touching the center circle. Other observers with telescope describe it as an oval planet. A few years later he once more observed Saturn, sketched a circle with equal sized loops on each side describing as a planet with “handles.” In a later session, adding to the mystery of the nature of the outermost planet the “handles” disappeared. Of course, we now know that Galileo had sketched the rings of Saturn at different stages of obliqueness to us. When the rings are edge on to us, they disappear. Saturn and the Moons of Mars Connection

“They have likewise discovered two lesser stars, or satellites, which revolve around Mars, whereof the innermost is distant from the center of the primary exactly

three of his diameters, and the outermost five: the former revolves in the space of ten hours, and the latter in twenty-one and a half.”

This is a quote from Jonathan Swift’s satire, Gulliver’s Travel that was published in 1726. Voltaire also mentions the twin moons of Mars in one of his fictional works. Asaph Hall didn’t discover the moons of Mars until 1877 more than a hundred and fifty years after Jonathan Swift published his novel. Of course this generated all kinds of fantastic tales to explain Swift’s source of this knowledge. His source probably had a more mundane origin: Kepler on a misconstruction of Galileo’s anagram announcing Saturn’s tri-form. When Galileo turned his telescope to Saturn he announced his findings to his colleagues in the form of an anagram, a common practice at that time to protect information from rivals before it was analyzed it and published. Galileo sent the following anagram telling its recipients it contained a coded message of his latest findings. smaismrmilmepoetaleumibunenugttauiras The intended solution was: altissimum planetam tergeminum obervavi “I have observed the highest planet triform” Kepler, who had an uncanny ability to detect patterns and sequences and thus very good at solving puzzles had a second solution. salve umbistineum geminatum martia proles “Be greeted, double knob, children of Mars.” There is no doubt that Kepler had Mars in mind when he worked the anagram. Galileo’s Daughter Like Tycho Brahe before him, Galileo Galilei never married the woman that bore his children and thus his three children (2 girls and a boy) like those of Tycho were considered illegitimate. Unlike Tycho, Galileo was not a descendant of a wealthy, noble family whose illegitimate children were recognized by the state and given every privilege, in his case the children were just considered bastard with no privileges.

Galileo had three children out of wedlock with Marina Gamba. Marina died in 1612 leaving the three minor children; Virginia age 12, Livia age 11 and Vincenzio age 5. The stigma of being illegitimate combined with the lack of a dowry, made the girls unfit for marriage. Shortly after Virginia turned 13, Galileo placed both girls in the Convent of San Mateo in nearby Arceti. The girls were too young to make such a decision for themselves. Through the offices of Cardinal Maffeo Barberini, one of his admirers, Galileo obtained a dispensation to be placed in the convent and remained there for the rest of their lives. Virginia took the name of Maria Celeste when she took the veil three years later. The name honors the Virgin Mary and her famous father’s profession—astronomy. The 124 letters she wrote to her father that have survived give a glimpse at the austere, short life of a nun. The letters that Galileo obviously treasured show a sweet, loving daughter, who greatly admired her father. Her sentence structure was long, complicated but very clear. Her transitions even in the most mundane subject were smooth showing a mastery of the language. The details in these passages provide a vivid image of the austere life she led without resentment. The convent was poor and did not have the wherewithal to feed its inhabitants and keep the complex in good order. Suor Maria Celeste managed the finances of convent initiating projects to raise funds and through the influence of her famous father obtained donations to keep San Mateo afloat. Galileo physically made repairs of the buildings and committed himself to keep the clock in good working order. Maria Celeste expressed great interest in her father’s work, discoveries, theories and correspondence with other astronomers. There is evidence that she helped prepare/edit copy for publication. Her letters show she would certainly be capable of such an endeavor. Galileo described Maria Celeste as “a woman of exquisite mind, singular goodness, and most tenderly attached to me.” Shortly before the Inquisition found Galileo guilty of heresy for his view that the earth was not the center of the universe, he moved to a house in Arceti within view of the convent. It was here that that the disgraced Galileo spent the rest of his life under house arrest. His loving daughter volunteered to recite part of the prayers assigned to him as part of his rehabilitation. Maria Celeste, who had always been sickly, contracted dysentery and died on April 2, 1634, aged 33.

My great admiration for Galileo diminished when I learned the fate of his daughters. In fact, I was horrified; how could a father place his daughters in a convent at such a young age? It would seem like I would do anything; raise a dowry, somehow legitimize their birth, just to give the girls just another option. However the letters paint an image of a loving, caring father who considered the limited options available for his daughters. The convent provided a relatively safe environment and an education. This lack of options ruled by unfathomable traditions that dictate the roles we must play based on gender, race, ethnic group or religion is so wasteful of mankind’s primary resource, the mind. Development of the Astronomical Telescope Early refracting telescopes, like the kind Galileo made, were designed to magnify an erect image. If the main purpose of the telescope is to see terrestrial objects an inverted image would be inconvenient. Galileo accomplished this by using a plano-convex objective (positive) lens and a concave eyepiece with the eyepiece lens set inside the focal length of the objective lens. The magnification (power) of the instrument is determined by the ratio of the focal length of the objective lens and the focal length of the eyepiece. However, the limiting factors of Galileo’s telescope were the field of view and resolution that depend on focal length of lenses and diameter of the objective lens respectively. With his most powerful instrument, he could only see one fourth of the moon. Christiaan Huygens figured the way to break this barrier to make both the objective and ocular positive lenses. The image would be inverted, but when you’re looking at star it doesn’t matter. Huygens invented the astronomical telescope. Christiaan with his brother Constantijn turned from designing to actually building the astronomical telescope. They could not find anyone that could grind a lens to their specifications, so they started grinding their own. It was difficult because of all the secrecy, but they found the technique and later even built a machine to help with the grinding task. With the acceptance of the astronomical telescope, the limit on magnification caused by the small field of view of the Galilean telescope was temporarily lifted, and a "telescope race" developed. To minimize optical defects (errors in curvature) and chromatic aberration (rainbow effect around bright images), objective lenses were made with rather shallow curvature. This meant objective lenses with long focal points. Beginning in the 1640s, the length of telescopes began to increase. From the typical Galilean telescope of 5 or 6 feet in length, astronomical telescopes rose to lengths of 15 or 20 feet by the middle of the century. Huygens’ 23-foot telescope with about 100 times magnification and the field of view of 17 arc-minutes was typical for the mid 17th Century. The advantage of the longer focal length meant higher magnification but you had by a very cumbersome instrument and a dimmer image.

Johannes Hevelius, a Polish brewer turned astronomer built a series of long focal length telescopes of 18m (about 60 ft.), 21m (about 70 ft.) and his biggest toy having a focal length of 46m (about 150 ft.) for his observatory, Sternemburg. He assembled his two smaller telescopes on top of the roof of three adjacent buildings. Hevelius used a mast 27.4 m (about 90 ft.) and a large crew to lift the objective end of the telescope into position for observing. As clumsy as these devices seem to handle, to find anything and to track, Hevelius used them very effectively publishing the most complete atlas of the Moon the Selenographia in 1647. His atlas was the first to name general features on the Moon, like “seas” then went on to name specific canyons, craters, etc. This atlas helped astronomers to study the Moon and became the standard handbook for a hundred years. Most of the names were long and cumbersome like the telescopes thus dropped in the modern Moon maps.

The large telescope did not fit on the rooftop so it had to assembled and used in an open field. The tube had to be built very strong to keep the lenses properly aligned and thus quite heavy. He needed a rather large crew to transport, assemble and use the telescope. It could be used only on the calmest night, the slightest breeze would flex the tube and the alignment lost. This telescope was seldom used. Astronomers built larger telescope with far longer focal lengths, over 300 feet, but the instruments were just too difficult to use.

The Aerial Telescope In the late 17th Century, Christiian Huygens came out with a new “concept” telescope, a tubeless instrument. The device consisted of an objective lens mounted inside a short iron tube mounted on

Figure 23 Johannes Hevelius' 18m Telescope

Johannes Hevelius assembled his telescope on the rooftop. He built a frame on sliding table to allow a few degrees of lateral as well vertical adjustment for observation.

Figure 24 Johannes Hevelius’ 46m Telescope

a swiveling ball-joint on top of an adjustable mast. The eyepiece was also mounted in a short iron tube and the two lenses were connected kept aligned with a taut cord or cable. The objective lenses grew in diameter as the focal lengths got longer. The Huygen brothers made objective lenses of 200 mm (8 in.) and 220 mm (8.5 in.) with focal lengths of 52 m (170 ft.) and 64 m (210 ft.} respectively. Huygens also devised an ingenious method for aiming the telescope. Extra long focal length telescopes were now practical.

Other astronomers made several variations of the aerial Telescope. Giovanni Cassini, the Italian born French astronomer used an aerial telescope in the

Paris observatory quite extensively. He found several moons around Saturn, One of the first to see the “Red Spot” on Jupiter and the first to detect a division in the ring of Saturn. He expressed the opinion that the rings were composed of “swarms” of moonlets too small to be seen individually. Adrirn Auzout made telescopes with focal lengths of 300 to 600 ft. and proposed making a huge aerial telescope of 1000 ft. in length so he “observe animals on the Moon.” He never got to see the animals. The Invention of the Reflecting Telescope Even the best, clearest, blown glass of the time had bubbles, impurities and imperfections that caused distortion in the image as you looked through it. In making lenses, opticians would select the clearest part of the glass plate and make that the center of the lens. Astronomers would often stop down, that is, cover the outside rim of the lens, and only use the center portion of the lens. Galileo would often stop down a three-inch lens to make a one-inch aperture. Besides the distortions caused by the imperfections of the glass and errors in the curvature of the lens you had the great bane of the singlet objective chromatic aberration caused the variations in focal lengths of the different frequencies of light characterized by the “rainbow” effect around bright images. Sir Isaac Newton Sir Isaac Newton is generally credited with for the invention of the reflecting telescope, that is, using mirrors instead of lenses in its construction and, indeed, produced the first working model in 1668. However the magnifying effect of concave mirror was well known and had been used by monks since medieval times. Leonardo da Vinci used concave mirrors to study the planets. Father Niccolo Zucchi built a reflecting telescope in 1616, but was unhappy with image and returned to making and using refractors. Any notes Father Zucchi may have made on his reflecting telescope

Figure 25 Huygen's Aerial Telescope

have not survived so we have no idea how he solved the problem of seeing the image without blocking it. Newton solved it by using a small flat mirror to reflect the cone of light to the side. Newton replaced the objective lens with a 6 in. (150 mm) metal mirror. He experimented with different alloys for reflectivity and found the mixture of six parts copper and two parts tin was almost as reflective as far more expensive and quick to tarnish silver. The primary delivered a converging cone of light to a flat secondary mounted at a 45° angle to the optical axis which directed the light to a focus outside the tube where an eyepiece could be placed. The telescope solved the chromatic aberration problem that had had plagued the refractors, but not the spherical aberration, that is the blurriness caused by the spherical nature of the mirror. Newton knew he need a parabolic shape for his mirror, but had given up on grinding non-spherical shapes. Father Marin Mersenne Father Marin Mersenne is better known for his work on music theory, Harmonie Universelle, published in Paris in 1636. The book, the most complete description of music theory in France at that time covered all aspects theoretical, theological, stylistic, acoustical and most important mathematical. In this section, Mersennes proposed a very advanced design for a reflecting telescope. He solved the viewing problem by adding a secondary reflective surface to project the converging cone of light through a hole in the center of the primary. This was the prototypical Gregorian or Cassegrainian design. The full implications of his work would not be understood until the twentieth century. Mersenne never built this telescope. His friend, Rene Descartes dissuaded him from this project, not because he thought it was a bad idea, but because the technology did not exist to make such precise curves on mirrors that at the time were made of tarnishable metal. Rene Descartes was right on this score, errors in curvature are much more forgiving in refractive lens than on reflective mirrors.1 James Gregory 1 Sant, Joseph (2016). The Early Reflecting Telescope: Cassegrain, Mersenne, and

Figure 27 Mersenne's Telescope Design

Figure 26 Newton's Reflecting Telescope

The telescope had a 6 in. concave spherical metal mirror as the primary.

James Gregory published his reflecting telescope design, later to be known as the Gregorian telescope, in 1663 but was not built until Robert Hooke made one in 1673. The design calls for a concave parabolic primary to collect light and direct it to a focus before a concave ellipsoid secondary mirror that reflects the immerging cone of light through a small hole in the center of the primary to the eyepiece behind the telescope. A concave parabolic mirror is needed to transform a plane wave of energy into a spherical wave to correct spherical aberration. Thus all reflecting telescope called for a parabolic concave primary mirror but those are very difficult to make at that time so most telescopes had spherical mirrors or at best approximately parabolic. Robert Hooke made the telescope with a spherical mirror.2 William Herschel William Herschel, an English astronomer of German origins, had a rather late vocation in the field for which he is best known. He immigrated to England as a musician becoming an accomplished music teacher, performer and composer. In studying the theory of music he came across Robert Smith’s Harmonics and that led to Smith’s A Compleat System of Opticks. Learning about telescopes whetted his appetite to view the night sky. Herschel began his study of the sky with refractors actually building four of varying apertures and lengths in 1773. He was not satisfied with the of the moon and the planets; he wanted to survey the whole sky--deep sky objects, little fuzzy blurs that looked like clouds and clusters of stars and for that you needed more aperture. He rented a Gregorian telescope and found that the reflector instrument was far easier to use than the refractor because the heaviest part, the mirror, was at the bottom. Herschel found great success in building Newtonian telescopes. It is with these that he started survey of the sky if the cataloged stars were truly singular of actually multiple stars. He was surprised on the number of binary and multiple star systems he found. In

2 Gregorian telescope. (2015, August 30). In Wikipedia, The Free Encyclopedia. Retrieved 02:56, August 7, 2016, from https://en.wikipedia.org/w/index.php?title=Gregorian_telescope&oldid=678664691

Figure 28 Gregorian Telescope Design The concave primary reflects a cone of light to a focus point in front of the concave secondary that in turn reflects the cone of light through a hole in the center of the primary to the eyepiece in the back of the telescope. The Gregorian telescope projects an erect image.

trying to determine the separation between these star systems he recognized the need for greater resolution. Increased focal length gives increased magnification and increased aperture gives increased resolution. William Herschel got “aperture fever,” a common malady among astronomers, building a series of ever larger telescopes culminating with his crowning achievement a forty foot long telescope with a four foot mirror. In making larger mirrors, he soon exceeded the capability of the local foundry so he started casting and grinding his own mirrors. His mirrors were made with an alloy composed of copper, tin and antimony in varying proportions. The Great Forty-Foot

With the £4000 grant from King George III, William Herschel built the largest telescope in the world at the time. It used a 120 cm (47.2 in) primary mirror with a 1200 cm (39.4 ft.) focal length. Herschel made his own eyepiece and with this telescope he could over 6,000 times magnification. William Herschel constructed the giant telescope between 1785 and 1789. It was not the standard Newtonian design; Herschel eliminated the secondary mirror and instead tilted the primary mirror to reflect the cone of light to a viewing cage near the top of the telescope. The 40

ft. tube, made of iron, was built with a hump to allow for the viewing cage and not obstruct the converging cone of light deflected to the side. Two mirrors were cast for this telescope. The first, a metal plate made of copper and tin and a little arsenic to improve finish, was two inches thick and weighed 1023 pounds. After the plate was ground and polished to the right shape, Herschel found that with the center 0.9 inch thinner than the edge the plate was to thin to hold the shape correctly. He had a second metal plate cast of double the thickness. However he used the original mirror while the second was being polished to remove tarnish.3 A Planet Named George 3 40-foot telescope. In Wikipedia, The Free Encyclopedia. Retrieved August 14, 2016 from https://en.wikipedia.org/wiki/40-foot_telescope

Figure 29 Great Forty-Foot

Figure 30 Herschelian Design

With the help of his brother Alexander and especially the assistance of his sister Caroline, William started a project to survey the complete sky. On March 13, 1781 he came across an object that didn’t quite look like a star. At first he thought it might be a comet and determined it was in orbit, but he could not detect a coma. His surveys had already brought renown to this talented household among the scientific community; this discovery sealed it. Herschel had discovered the seventh planet. As a 6th magnitude object, it is actually visible to the naked eye, but it is small and its 84 year orbit around the sun is so slow, the ancients missed in identifying it as one of the “wondering” stars. William Herschel became famous overnight catching the attention of King George III who had a keen interest in science. In 1782, the king offered a pension and the post of royal astronomer provided he moved near Windsor castle “so he could look through his telescope.” At age 43 William Herschel started his professional career as an astronomer. Herschel named the discovered planet Geogium Sidus in honor of his patron, King George III. The name was never popular outside of England and eventually took Johann Bode’s suggestion to name for the Greek god, Uranus, the father of Saturn.4 Caroline Herschel: A Cinderella Story The first woman to discover a comet, officially recognized in a scientific position and received membership into the prestigious Royal Society, Caroline Lucretia Herschel was the eighth child of Jewish oboist, Issac Herschel, and his illiterate bellicose wife, Anna Ilse Moitzen. At age ten Caroline was struck with typhus. The disease stunted her growth, never growing past four feet three inches, and affected her vision in her left eye. She got a cursory education learning to read/write and elementary arithmetic like all her siblings but denied the benefits of extended home schooling. Her mother did not see the purpose of Caroline learning music, dressmaking, needlepoint or even French when she was simply too ugly to marry. As the youngest surviving girl she was loaded with house chores in preparation for the only the only career open to her: housemaid. A more unlikely candidate to be an accomplished astronomer is hard to even image.

4 William Hershel, (2016 August 7) In Wikipedia, The Free Encyclopedia. Retrieved 17:10. August 9, 2016 from https://en.wikipedia.org/wiki/William_Herschel

Figure 31 Replica of William Herschel Telescope

Her brothers, William and Alexander rescued the deformed, diminutive lady from a life of servile servitude from the clutches of their mother by proposing that Caroline join them in Bath, England on a trial basis as a singer for in William’s church performances. Anna agreed to release Caroline as her maid only with the assurances that William would pay her for the services of a full-time maid. At age twenty-two, Caroline left Hanover and joined her brothers at Bath. She agreed to do household chores, learned to play the harpsichord and started singing lessons becoming an accomplished singer in Williams’s oratorio concerts. She was now in demand as a singer and well on her way to total financial independence in her musical career. William was also doing well in his musical career when he got interested in telescope making leading into study of the sky. It is hard to determine if Caroline coincidently got interested in astronomy as her brothers or if she entered the field out of a sense of duty to her brother. In either case there is no doubt that if there was some pretense at the start, it evaporated becoming genuine and intense. She started in this new field as an assistant to William recording his observations of deep sky objects in his twenty-year project to survey the complete sky, culminating in the publishing of the most complete star catalog of the time, the New General Catalogue (NGC) with about 2500 objects. The catalog now contains 7,840 objects. Caroline used a smaller Newtonian telescope to study the sky on her own. In her survey of the sky she discover an open cluster and fourteen new nebulae. On August 1, 1786 she discovered the first of eight comets she would discover over her lifetime. In 1787, King George III recognized Caroline as an astronomer and hired her as William’s assistant paying her a small pension making the first woman paid for scientific work. After William’s death in 1822, Caroline returned to Germany but continued to work on their catalog of nebulae. The Royal Astronomical Society awarded Caroline Herschel a gold medal in recognition for her contributions to science in 1828 and seven years later inducted her as an honorary member of the society. She died in 1848 at age 97. She penned the inscription that is on her tombstone: "Theeyesofherwhoisglorifiedherebelowturnedtothestarryheavens."5

5 http://www.space.com/17439-caroline-herschel.html 15 august 2016