The Role of Images in Astronomical Discovery Read online

  preparations for injections and preservations in wax casts or organs in jars. These highly

  illustrated publications have played an important role in training students, future surgeons

  and midwifes.17 In Chapters 9–11, I will describe how atlases of galaxies have fulfilled a

  similar role for astronomers.

  More broadly, several of the most famous artists of world art history have produced sub-

  lime works illustrating nature. Leonardo da Vinci (1452–1519) and Rembrandt van Rijn

  (1606–1669) were among the greatest illustrators of natural scenes. They gave to the art of

  scientific drawing its lettres de noblesse. Beyond their artistic value and technical achieve-

  ment, sketches and drawings have played a profound epistemological role.

  Finally, illustrations are the visual tool to convey the reality of what has been observed.

  Images allowed the test of independent verification or reproducibility by other observers. In

  earth sciences, drawings and illustrations were a guarantee that the researchers themselves

  had been in the field. “A savant had to show that he had indeed seen these features with his

  own eyes, that he had been there and studied them for himself, before he could establish any

  credibility or authority to pronounce on their scientific explanation.”18 This was particularly

  true for the geologists, volcanologists and naturalists of the nineteenth century, such as

  Charles Lyell, Louis Agassiz and Charles Darwin (Fig. 2.2).19

  Drawing Celestial Objects

  Astronomy has its own challenge. The technical set-up and atmospheric conditions under

  which astronomical observations are conducted are highly important and affect what is

  viewed. The faintness of most celestial objects has always required the use of the finest

  instruments with large collecting light power. In spite of using the best instruments, “neb-

  ulae” appeared fuzzy, featureless and colourless. The temperamental nature of the atmo-

  sphere easily blurred or extinguished the images seen through the eyepiece. If astronomical

  16 L. Daston and P. Galison, Objectivity, New York: Zone Books, 2007, pp. 69–82.

  17 There is an extensive discussion of atlases of anatomy in L. Daston and P. Galison, The Image of Objectivity, Representations, No. 40, Special Issue: Seeing Science (Autumn, 1992), Berkeley: University of California Press: pp. 81–128.

  18 M. J. S. Rudwick, Bursting the Limits of Time: The Reconstruction of Geohistory in the Age of Revolution, Chicago: University of Chicago Press, 2005, p. 42.

  19 C. Lyell, Principles of Geology, New York: D. Appleton and Company, 1872.

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  2. Portraying Cosmic Whirlpools

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  Fig. 2.2 View looking up the Val del Bove, Etna. In November, 1828, Charles Lyell made the draw-

  ing on which the engraving is based. From Lyell (1830–1833), Principles of Geology. Courtesy of

  Bibliothèque, Université Laval.

  sketching followed a rather conservative development, it was considered for a long time far

  superior to what early photography could deliver.

  In the pre-telescopic age, drawings of celestial objects dealt mainly with bright objects

  such as the Moon, comets, meteor showers or various asterisms. On a grand scale of visual

  representation, several splendid atlases of the sky with stars superimposed on the mytho-

  logical figures of constellations were produced: for example, the superb Uranometria of

  the German lawyer and celestial cartographer Johannes Bayer (1572–1625) in 1603. Dan-

  ish astronomer Tycho Brahe (1546–1601) ran his own press at Uraniborg and he illustrated

  his books very well. Brahe’s famous figure of the stella nova depicting the great supernova

  of 1572 in the constellation of Cassiopeia continues to be used by modern astronomers.20

  In Sidereus Nuncius of 1610, Galileo Galilei presented several drawings of asterisms, or

  remarkable groupings of stars. Notable is Galileo’s sketch of stars in the belt and sword of

  the Orion constellation, where he distinguished stars visible with the naked eye and those

  seen only with the aid of his telescope.

  Indeed, with the advent of the telescope, things changed dramatically by allowing views

  of a multitude of new objects. Sketching became essential to report and communicate the

  “new worlds.” Words and written descriptors were not sufficient. As reproducibility by dif-

  ferent observers was an important component of the verification process, drawing became

  20 Tycho Brahe, Astronomae Instauratae Progymnasmata, Frankfurt, 1610.

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  Part I – Images and the Cosmos

  an essential tool.21 However, the faintness of many of the objects under study and the tur-

  bulent atmosphere remained continuous challenges.

  Studied with the telescope, the Moon was an instant favorite for sketching and graphic

  reporting. Within months of each other, English astronomer Thomas Harriot and Galileo

  made the first known drawings of the Moon as viewed through low-magnification tele-

  scopes. Harriot is considered to be the first to have observed the Moon through a telescope

  as per his drawings executed on 26 July 1609, around 0900 hrs. As the number of telescopes

  and users grew, our natural satellite was mapped in its entirety during the first few decades

  of the seventeenth century.

  Mapping and drawing of the Moon culminated with the publication of Selenographia,

  sive Lunae description, in 1647; this supreme work was the milestone achievement of

  Danzig mayor and master brewer Johannes Hevelius (1611–1687). For this formative work,

  Hevelius has been called the founder of lunar topography. With telescopes improving over

  the next two centuries, drawings of the Moon continued to be valued. Lunar drawings even

  became the indicator of the power and quality of any new instrument. A climax was reached

  when Scottish astronomer and engineer James Hall Nasmyth (1808–1890) presented his

  drawings of the Moon “to educate the eye” at the 1851 Great Exhibition in London where

  he received a gold medal.22

  In 1659, Dutch astronomer and physicist Christiaan Huygens (1629–1695) published his

  highly illustrated book, Systema Saturnium. In this work, Huygens summarized his research

  on Saturn, its system of rings and its satellite, Titan, which he had discovered in 1655. The

  sketching work was very well presented and emphasized Huygens’ interpretation of the

  nature of the rings. The book became the definitive work about the saturnian world, in part

  because of the extent and quality of its illustrations.

  Drawing the Dazzling Sun

  The Sun is bright and, for early observers, its surface showed interesting features such as

  sunspots and faculae (see Fig. 0.8). As these features appeared and dissolved with time,

  tracking their changes became the driver for daily sketching of the solar surface. Harriot,

  Galileo, German Jesuit astronomer Christopher Scheiner (1573–1650), Frisian/German

  astronomer Johannes Fabricius (1587–1616) and several observers took turns at mapping

  the solar surface and its transient sunspots. Astonishingly, early observers used no eye pro-

  tection of any sort. Quickly peeping at the blinding image of the Sun, they got glimpses of

  its dazzling surface. Thankfully, the much safer and more reliable technique of projectin
g

  the solar image, introduced by Scheiner, was adopted.

  The discussion of the nature of sunspots led to an interesting and controversial exchange

  between Galileo and Scheiner. Galileo was promoting an explanation that sunspots were

  21 S. Schaffer, On Astronomical Drawing, in Picturing Science, Producing Art, C. A. Jones and P. Galison (editors), New York: Routledge, 1998, pp. 441–474.

  22 J. North, Cosmos: An Illustrated History of Astronomy and Cosmology, Chicago: University of Chicago Press, 2008, p. 489.

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  2. Portraying Cosmic Whirlpools

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  Fig. 2.3 Drawing of the large 1859 sunspot group. The white light flare is indicated as A, B, C and

  D, features that evolved over minutes but were caught by astronomer Richard Carrington. From Car-

  rington (1859), Monthly Notices of the Royal Astronomical Society.

  truly part of the surface of the Sun. Scheiner, anonymously hiding under the pseudonym

  Apelles, claimed for some time that they were satellites around the Sun. The observations

  and sketches of the Sun were the main themes of the first astronomy book on the Sun pub-

  lished in Italian and Latin in 1613 (see Fig. 0.8).23 The book presented numerous sketches

  of the solar surface; for example, the evolution of the solar surface and its spectacular dis-

  play of sunspots can be followed over several weeks of the month of June 1612 (Fig. 0.8).

  The features sketched are very familiar to a modern observer of the Sun.24

  Some of the historical solar drawings have been used to reconstruct the historical record

  of solar activity. Interesting or new solar phenomena were discovered and recorded with

  the aid of drawings. German astronomer Wilhelm Tempel (1821–1889) made a drawing of

  the solar corona during the eclipse of 18 July 1860. By coincidence, it captured a coronal

  mass ejection in progress, a phenomenon that we recognize today as most important for

  space weather and solar–terrestrial interactions. On 1 September 1859, British astronomer

  Richard Carrington observed an intense solar flare in white light; the rare event lasted only

  five minutes, but he made an accurate drawing of it (Fig. 2.3).25 Carrington, “the last serious

  23 On Sunspots: Galileo Galilei & Christoph Scheiner, Translated and introduced by E. Reeves and A. van Helden, Chicago: University of Chicago Press, 2010.

  24 H. Bredekamp, Galilei Der Künstler: Der Mond, Die Sonne, Die Hand, Berlin: Walter De Gruyter Inc., 2009.

  25 R. Carrington, Description of a Singular Appearance Seen in the Sun on September 1, 1859, Monthly Notices of the Royal Astronomical Society, 1859, Vol. 20, pp. 13–15.

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  and most tragic of grand amateur astronomers,” had discovered solar flares.26 He accurately

  sketched this particular event; it was so powerful that it appeared as an unusual imprint, a

  sharp localized harsh brightening of the solar photosphere. He correctly related the solar

  event to the powerful magnetic storm that hit the Earth 16 or 17 hours later. Reporting on

  Carrington’s observation, the Royal Astronomical Society commentator cautiously stated:

  “While the contemporary occurrence may deserve noting, he [Carrington] would not have it

  supposed that he even leans towards hastily connecting them. ‘One swallow does not make

  a summer’.” However, Carrington had recorded the right “swallow.” We know that major

  geomagnetic storms are triggered by solar flares.

  Drawing Sidereal Condensations and “Nebulae”

  Until the beginning of the twentieth century, “nebulae” were a mixed bag of objects and no

  one made a distinction between local fluorescent gas clouds, objects members of the Milky

  Way, and the giant external stellar systems, the “island-universes” known today as galaxies.

  Even poorly resolved star clusters were called “nebulae.” Drawing, sketching and portray-

  ing of “nebulae” became the vogue. However contrary to the Moon or the Sun, “nebulae”

  turned out to be frustratingly difficult objects to draw.

  The first known (and preserved) drawing of a nebula is attributed to Giovanni Batista

  Hodierna (1597–1660) for his sketch of the Orion Nebula, a nearby gas cloud made fluores-

  cent by ultraviolet light from a few very luminous embedded young stars. A self-educated

  mason and shoemaker, Hodierna had become a priest and an astronomer. An enthusiastic

  supporter of Galileo, he studied nebulous objects, noting differences between comets and

  “nebulae.” He surmised that comets were made of terrestrial matter, while “nebulae” were

  made up of stars. He listed and described 40 objects that appeared nebulous to the naked

  eye but resolved into stars with the aid of the telescope. He used the degree of resolvability

  to classify “nebulae.” French astronomer Guillaume Jean-Baptiste Le Gentil (1725–1792)

  is also attributed an early sketch of the Orion Nebula.

  As we saw in the previous chapter, French astronomer Charles Messier (1730–1817) was

  mainly interested in comets. Nevertheless, Messier made several drawings: among his most

  famous are those of Messier 31/32/110 (the Andromeda Galaxy and its two companions)

  and of Messier 42 (the Orion Nebula). The first trio of objects are now recognized as genuine

  galaxies while the latter is the archetype of star-forming regions.

  At the end of his 1811 summary paper on the thousands of “nebulae” and star clusters

  that he recorded with Caroline, William Herschel showed two plates with engraving of

  “nebulae,” illustrating their multiple shapes and degrees of condensation (Fig. 2.4).27 The

  illustrated “nebulae” are a mixed bag and are drawn as blurry patches, some with appen-

  dices. Our modern eye, trained by photography and a better knowledge of the range of

  26 A. Chapman, The Victorian Amateur Astronomers, Independent Astronomical Research Astronomy in Britain 1820–1920, Chichester: Wiley, 1998. pp. 40–41.

  27 W. Herschel, Astronomical Observations Relating to the Construction of the Heavens, Philosophical Transactions of the Royal Society of London, 1811, Vol. 101, pp. 269–336.

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  Fig. 2.4 Drawings of several “nebulae” by astronomer William Herschel, one of two plates he pub-

  lished in the Philosophical Transactions of the Royal Society of London (1811). Courtesy of Omar

  W. Nasim.

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  Part I – Images and the Cosmos

  objects, does recognize the different types of “nebulae”: the true nebulae as luminescent

  gases of star-forming regions or the planetary nebulae of dying stars, or the more regularly

  shaped extragalactic “nebulae,” or galaxies. Herschel proposed an interpretation of the neb-

  ular shapes using the conceptual frameworks of Isaac Newton’s law of gravitation and the

  Nebular Hypothesis. The gravitational force, he surmised, determines the shape and the

  degree of condensation. Herschel even speculated that comets might be the most advanced

  stage of nebular condensation.

  The advent of several telescopes boosted interest in nebulous objects. “Gradually, neb-

  ula hunting was becoming a pursuit of its own right, althoug
h for long it was held in less

  esteem than comet hunting.”28 As the nineteenth century moved forward, imaging “neb-

  ulae” became an art and a science as waves of astronomers attempted to catch the elu-

  sive and diaphanous shapes. These efforts have been discussed and analyzed in depth by

  Omar W. Nasim in a superbly illustrated monograph presenting the works of several emi-

  nent observers: John Herschel, Samuel Hunter, Ebenezer Mason, William Lassell, Wilhelm

  Tempel and those of the Third Earl of Rosse’s team.29 Although astronomers drawing “neb-

  ulae” were completely ignorant or incorrectly conceived their nature, they managed to pic-

  ture the objects reasonably well most of the time. The reproducibility by drawings of the

  same object by different observers remained questionable and some sketches are impossible

  to relate to the objects captured by modern photographs. Nevertheless, overall, in answer to

  the question of the beginning of this chapter, it can be said that it is possible to draw objects

  without a clue of what they are. A most dramatic example is the engraving of the great

  nebula in Orion by the Fourth Earl of Rosse.30 When compared to a fine black-and-white

  modern photograph, the precision of the details and overall shape seen in the drawings are

  stunningly similar.

  William Parsons and the Leviathan

  The systematic use of drawings as faithful representations of “nebulae” observed through

  telescopes enjoyed a significant boost with the work of the Third Earl of Rosse, William

  Parsons (Fig. 2.5) and his team of skillful observers at Birr Castle, Ireland.

  For a time a member of Parliament, Parsons ran one of the most ambitious and origi-

  nal scientific enterprises of the nineteenth century.31 Well endowed through marriage with

  family land and fortune, Parsons leveraged these assets to realize and empower his pas-

  sion for astronomy. His wife Mary Field, Countess of Rosse (1813–1885), a fine pio-

  neer photographer herself, wholeheartedly supported her husband’s astronomical projects.

  “Mary was an intellectual young woman, perhaps no great beauty, as she appears thin and

  28 J. North, Cosmos: An Illustrated History of Astronomy and Cosmology, Chicago: University of Chicago Press, 2008, p. 443.

  29 O. W. Nasim, Observing by Hand: Sketching the Nebulae in the Nineteenth Century, Chicago: University of Chicago Press, 2013.