Astronomical Seeing

Elizabeth A. Kessler

Eighth Anniversary Image of Hubble’s Smash Hits

Based on the large number of Hubble images and their widespread circulation, it is easy to assume that their production was the telescope’s primary purpose. The elements fundamental to astronomical observing since the late nineteenth century – light, telescopes, and cameras – support such a conclusion. Each seems grounded in an experience of vision. Light enables seeing, whether reflected off of objects or emitted by them. Telescopes extend that vision by allowing humans to see images of distant objects and scenes. Lenses, whether part of the optical system of an eye or of a telescope, project images. Photographic cameras record pictures. Since the invention of the camera it has been understood as a surrogate for the human eye. As William Henry Fox Talbot writes, ‘[The Camera] may be said to make a picture of whatever it sees. The object glass is the eye of the instrument – the sensitive paper may be compared to the retina’ (1992: 87).1 At its most basic, astronomical observation – a word that itself connotes sight – depends on vision as well as on the devices that enhance and imitate it.

Star Cluster NGC 2074 in the Large Magellanic Cloud

However, if the same elements of astronomical observation are understood in terms of the physical processes at work, a different notion emerges, one that places greater emphasis on abstract data and underplays the senses. Scientists separate light from vision when they define it as measurable energy; instead, it becomes a series of numeric values that corresponds to wavelength or intensity, attributes that the naked eye may or may not discern and never with the precision of an instrument. Reducing light to its measurable properties and subtracting out the sensory elements subtly changes how one understands the instruments used for recording the cosmos. The telescope becomes a device not for seeing but for magnifying measurable quantities of light. A camera is a technology not for taking pictures but for recording how many photons a distant object emits. With the use of digital cameras that record becomes a numeric value. Reframed in these terms, the Hubble Space Telescope turns into an instrument for collecting data about the amount and type of energy in different regions of the cosmos, data that can be analyzed through reason.

Arguably, both ways of understanding the Hubble Space Telescope are correct. It is simultaneously an instrument of vision that returns pictures and a device that collects numeric data. As such it embodies what the historian of science Peter Galison identifies as a common tension within science, that between images and data.2 As one might expect, each mode of representation has a different function within science. While images show the specificity and complexity of the world in a manner that engages human intuition, data invite logical analysis and abstraction. Considered in these terms, a possible connection between the telescope and Kant’s sublime lies within the very makeup of its observations. Their dual nature, the fact that they are simultaneously understood as appealing to the senses and to reason, has the potential to bring together the two faculties that the philosopher saw as fundamental to the sublime.

A Glowing Pool of Light: Planetary Nebula NGC 3132

Rather than take up the aesthetic experience, Galison focuses on the separate uses of these different modes of representation as well as the translation from one to the other. Through examples from several different areas of science he demonstrates that both have a place within the pursuit of scientific knowledge, and he carefully states that he intends ‘neither to bury the scientific image nor to sanctify it’ (2002: 301). Scientists, however, have often adopted a far less diplomatic stance. Galison’s aphoristic summary of the attitudes of scientists – ‘We must have images; we cannot have images’ – speaks to the ambivalence of their attitudes toward visual representations (300). The rap on images is familiar; the senses are easily tricked and deceived, whereas the analysis of numeric data calls on the certainty of reason. While images may have their place, numbers and logic come out ahead. No scientist would replace the terms in Galison’s phrase and suggest a ban on data.

Despite the preference for quantitative methods, the practices of astronomers push against this. Even as some demean images, others find them scientifically and aesthetically valuable; sometimes the same person holds both views. Considering science in a wider context and as a human endeavor makes evident the variety of anxieties and concerns that orbit around images. The history of the Hubble Space Telescope, perhaps more markedly than any other scientific project, illustrates that science is a very human endeavor. It is subject to shifts in plans, mistakes, and equally remarkable moments of success. The place of images through this history – from the ambivalence that dogs them to the embrace embodied by programs like the Hubble Heritage Project – underscores the critical place of the senses in astronomy. As discipline, it never fully abandons images and therefore it is possible to experience the sublime because the imagination, a critical element of the aesthetic experience and one that Kant associated with the senses, is not left behind.

Cone Nebula (NGC 2264): Star-Forming Pillar of Gas and Dust

While ambivalence toward images characterizes all branches of science, astronomy’s relationship to seeing and picturing is an especially vexed one. Unlike other scientists such as biologists or chemists who can probe and manipulate the materials and phenomena they study, astronomers can only look. The notions of light, telescopes, and cameras discussed above already establish the centrality of vision, and the history of astronomy’s engagement with these elements only further solidify the connection. Astronomy’s history intertwines with that of optics, and astronomers such as Kepler and Newton contributed to scientific understandings of vision and light. Galileo’s telescope stands out as the first instrument to radically amplify our sensory experience. Astronomers also assisted with the development of devices for making images. John Herschel corresponded frequently with Talbot about chemical methods for fixing light, and he gave the name ‘photography’ to the process developed by Talbot (see Schaaf, 1992). In more recent years, astronomers have helped to enhance the performance and adaptability of digital detectors, a now omnipresent imaging technology.

The practice within astronomy of producing one pictorial representation for scientific analysis and another version for public display both confirms and complicates attitudes toward images (see Lynch & Edgerton, 1988). The sociologist of science Michael Lynch and the art historian Samuel Edgerton document this approach in an ethnographic study focused on image processing that they conducted in the late 1980s. When the researchers asked about aesthetics, the astronomers repeatedly discussed the pictures they made for public presentations, magazines, and journal articles. While many took great pride in these photos, the astronomers considered images made for display as separate from their research agendas as well as less important. The language they used revealed their underlying ambivalence toward visual representations, and they often referred to the polished color images as ‘pretty pictures’.3

As an aesthetic category, a peculiar ambiguity distinguishes prettiness from other sensory experiences.4 To judge something as pretty both acknowledges the sensual pleasures it provides and points to its inadequacies, a lesser position underlined when the word is modified as ‘more than pretty’ or ‘merely pretty’. A woman who is called pretty may feel genuinely complimented but also wonder why she does not measure up to the standard of beauty. Although a notch above the ordinary, prettiness is common and conventional enough to approach the banal. I might notice a pretty scene in passing, but it does not absorb my interest. It is something that catches my attention briefly and then disappears, remembered, if at all, as only a vaguely pleasurable experience. Even when pretty shifts from adjective to adverb, it tempers the word it accompanies. A pretty good day could always be better. The possibility of a higher aesthetic level that has not been reached, one that would elicit a response of much greater depth and value, stands behind every use. Prettiness makes no claim of distinctiveness, but apologizes for what is missing.

Butterfly Emerges from Stellar Demise in Planetary Nebula NGC 6302

In its focus on shallow pleasurable sensations, prettiness shares some attributes with Kant’s notion of the agreeable. In The Critique of Judgment he defines the agreeable as ‘what the senses like in sensation’. The sublime brings into relationship the sensible and the supersensible, the imagination and reason. In contrast, the agreeable is based entirely on sensations and elicits only an increasing appetite for such sensations. In the end, the agreeable does not ‘contribute to culture, but it belongs to mere enjoyment’ (Kant, 1987: 126).5 Kant’s most colorful and amusing characterization comes when he describes it as ‘all those charms that can gratify a party at table such as telling stories entertainingly, animating the group to open and lively conversation, or using jest and laughter to induce a certain cheerful tone among them . . . the whole point is the entertainment of the moment, not any material for future meditation or quotation’ (173). The agreeable and the pretty share an emphasis on fleeting sensual enjoyment that does not linger or resonate.

The lesser position of astronomical images made for display derives most immediately from their pictorial nature. The phrase ‘pretty pictures’ implies a comparison to representations in another mode, namely, numbers and mathematics. Pictures cannot match the precision and elegance of equations or calculations. Also, their specificity closes off the possibility of making abstract and general statements about the nature of the cosmos, statements that are possible through statistical analysis. The highest aesthetic regard then belongs to a different system of representation, and pretty pictures falter before scientists even evaluate their sensual qualities. By their very definition as pictures, they cannot attain the beauty of mathematics.

Hubble’s Deepest View of Universe Unveils Never-Before-Seen Galaxies

Nonetheless, not all astronomical images are tagged as pretty. Many examples of great interest to scientists are blurry, black and white, and difficult to decipher. They show astronomers details that lay at the edge of the telescope’s resolution, where noise and signal are difficult to distinguish. As Lynch and Edgerton argue, these pictures have aesthetic aims too, in particular a desire to make clear what is obscure. But astronomers do not make claims about their attractiveness or expect them to evoke emotion, at least not in the usual sense. Instead, they position these images as akin to numeric data, requiring reason and logical thought for their analysis. In some regards, the production of highly polished, colorful images compensates for astronomers’ reliance on vision and visual representations. Creating two categories of images – one explicitly judged as less valued but aesthetically compelling –opens up the possibility for images that might avoid the pitfalls that accompany visual representations.

Some scholars, most notably the art historian James Elkins, have responded to the divide between images for display and those for scientific analysis by calling for more attention to less self-consciously aesthetic astronomical images. Elkins writes in Six Stories from the End of Representation that ‘outside the poison well of sentiment and sensationalism there is a truly lovely desert of astronomical images that do not try to be pretty’ (2008: 89). While such images raise another set of questions about aesthetics, some of which Lynch and Edgerton answer, and while they contribute to the advancement of science in a different way from those made for public display, Elkins’s harsh dismissal of the colorful views of the cosmos fails to acknowledge their larger cultural significance. It also accepts with little question the aesthetic judgments of the scientists, whose relationship with images is far from simple.

[…T]he Hubble images evoke the sublime, not mere prettiness, and engage both the senses and reason. Unlike many NASA missions, which last for a few weeks or even years, the Hubble Space Telescope has returned images for more than two decades, including world-famous icons like the view of the Eagle Nebula. Other large observatories have longer histories, but they do not have the marketing juggernaut of NASA behind them. The Hubble Heritage Project, a group dedicated to the regular release of visually compelling images, also makes the telescope unique. While press or public relations offices for other observatories regularly release images, no other astronomical research center boasts a group that functions as a hybrid of science, art, and public relations. Furthermore, the Hubble’s years in orbit also largely coincide with the rise of the Internet as a widely available communication medium, and the telescope’s images circulate online more widely than perhaps any other set of scientific representations.

The Eagle Has Risen: Stellar Spire in the Eagle Nebula

This apparent embrace of images emerged against a backdrop of ambivalent attitudes about images. As such the history of the Hubble Space Telescope, an instrument associated both with the promise of extended vision and marked by the difficulties of achieving it, offers an opportunity to consider how this ambivalence plays out and how astronomers attempted to resolve this tension in the case of the Hubble images. We can trace several aspects of this uncertainty through the history of the Hubble Space Telescope images from the early planning stages of the instrument through the formation of the Hubble Heritage Project in 1997. Four sets of images function as benchmarks in this history: representations of the telescope that predate its launch, photographs used to promote the Hubble’s primary camera, the Hubble’s view of the Eagle Nebula, and the images produced by the Hubble Heritage Project. These different moments illustrate the variety of anxieties that accompany images and image making, from uncertainty about extending vision through technological means to the fear that the senses will overtake reason. In the end, several astronomers and the institutions that support them recognized the value of seeing the Hubble’s return as simultaneously engaging both imagination and reason, thereby deepening the relationship of these images to notions of the sublime.

Eagle Nebula (M16) Pillar Detail: Portion of Top


1 Emphasis in the original.

2 Galison first explored these two modes of representation through the material culture of particle physics and an analysis of the instruments employed in this context. While some instruments were image-making devices, others were logic devices, which counted phenomena. See Galison, Image and Logic. Galison identified the same tension in other physical sciences in a later essay titled ‘Images Scatter into Data, Data Gather into Images’.

3 The phrase is not unique to astronomy but used in other scientific disciplines as well. Also, the idea of producing one set of images for scientific analysis and another for public display has a long history that crosses disciplinary boundaries. For one example, see Jennifer Tucker on Victorian images of bacteria in Nature Exposed, 159-93.

4 For a longer reflection on prettiness in the Hubble images, see Kessler, ‘Pretty Sublime’, 57-74.

5 One might also align prettiness with kitsch, which the art critic Clement Greenberg also described as an easily consumed sensory pleasure with no effect on culture. Greenberg, however, opposes kitsch with the avant-garde. While I have already demonstrated the value of the sublime for understanding the Hubble images, with their reliance on established visual tropes they could not be considered avant-garde.


Galison, P. (1997) Image and Logic: A Material Culture of Microphysics. Chicago: University of Chicago Press.

Galison, P. (2002) ‘Images Scatter into Data, Data Gather into Images’. In Iconoclash (eds), B. Latour and P. Weibel. Cambridge, MA: MIT Press, 300-23.

Kessler, E.A. (2011) ‘Pretty Sublime’. In Beyond the Finite: The Sublime in Art and Science (eds), R. Hoffman & I. Boyd White. Oxford: Oxford University Press, 57-74.

Lynch, M. & Edgerton Jr., S.Y. (1988) ‘Aesthetics and Digital Image Processing: Representational Craft in Contemporary Astronomy’. In Picturing Power: Visual Depiction and Social Relations (eds), G. Fyfe & J. Law. London: Routledge, 184-221.

Schaaf, L.J. (1992) Out of the Shadows: Herschel, Talbot, and the Invention of Photography. New Haven: Yale University Press.

Talbot, W.H.F. (1992) ‘The Pencil of Nature’. In Henry Fox Talbot: Selected Texts and Bibliography (ed.), M. Weaver. Santa Barbara, CA: ABC-Clio, 75-104.

Tucker, J. (2005) Nature Exposed: Photography as Eyewitness in Victorian Science. Baltimore: Johns Hopkins University Press.


This is an excerpt from Elizabeth A. Kessler’s book, Picturing the Cosmos: Hubble Space Telescope and the Astronomical Sublime (Minneapolis and London: University of Minnesota Press, 2012). Copyright 2012 by the Regents of the University of Minnesota. We are grateful to the Press for granting us permission to republish it here.

All images have been taken from HubbleSite, a website of the Space Telescope Science Institute (STScI). Material credited to STScI on this site was created, authored, and/or prepared for NASA under Contract NAS5-26555. The website states that ‘no claim to copyright is being asserted by STScI and [the material] may be freely used as in the public domain in accordance with NASA’s contract’.

Elizabeth A. Kessler teaches at Stanford University. She has been awarded fellowships by the Smithsonian Institution National Air and Space Museum.

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