Friday, April 24, 2015

25 years of Hubble images from space: strange, alien, phenomenal—and yet somehow, familiar.

This image created by the Hubble Space Telescope
is often referred to as the "Pillars of Creation." It has
been a common subject for painters such as Thomas Moran.


BY ELIZABETH A. KESSLER
Stanford University


On April 24, 1990, NASA launched the Hubble Space Telescope into its orbit above Earth. During its 25 years in space, astronomers have used Hubble data to develop vividly colored, highly resolved, and carefully composed pictures of nebulae, galaxies, and star fields. These sublime pictures now define how we see and imagine the universe.

To celebrate Hubble’s years of observing the cosmos, NASA has added a new image to the telescope’s gallery. The picture centers on Westerlund 2, a giant star cluster located in the constellation Carina, and it exhibits many of the characteristics made familiar by earlier Hubble images. This is not a universe in stark black and white, but the heavens on display in a full spectrum of vibrant hues—blues, reds, and purples. The sharply resolved details of the nebula give a sense of mass and volume to the pillars of gas and dust that reach out of its curving form. In the foreground, the gaseous clouds are dark, but they brighten as they recede into the distance. The change in contrast gives the picture depth. It invites us to explore the vastness and complexity of the nebula, to travel through what NASA’s press release describes as “a fantasy landscape of pillars, ridges, and valleys.” As with many other Hubble images, it’s a picture that evokes an experience of awe and wonder.

Many of the best-known Hubble images encourage this kind of response through a resemblance to landscape paintings and photographs of the American West. For example, the Hubble’s famous picture of a small region of the Eagle Nebula, often called the “Pillars of Creation,” orients the scene so the towers reach toward the top of the frame. The dramatic light that shines from behind pulls our eyes upward, further emphasizing the verticality and monumentality of the forms. It brings to mind the rocky towers that are icons of the American West, and a common subject for painters and photographers such as Thomas Moran, William Henry Jackson, and Timothy O’Sullivan. The color scheme chosen by astronomers who crafted the image lend support to the analogy. The hues map the relative wavelengths as registered through different filters on the Hubble’s camera, but it also means that we see towers of yellow, red, and brown with a blue-green sky in the background. In sum, the astronomers who translated the Hubble data into a picture carefully balanced the need for a scientifically valid image with the desire for aesthetically compelling one.

The similarity to the American landscapes encourages a particular response. The images show us strange and alien scenes, and they remind us about the vast size and scale of the cosmos and the celestial objects within it. But they also look familiar. They look like places that we could imagine visiting.

Despite the invitation, the Eagle Nebula and Westerlund 2 are too far away for humans or even our space probes to reach. They depict a frontier that we can only cross in our imaginations, or in a figurative sense, as astronomers learn more about the physical process at work in the universe.

Most of the time, astronomers and image processors at NASA and the Space Telescope Science Institute (the research center charged with the management of the telescope) have left it to our imaginations to take us over that frontier. (Movie fan—whether science fiction buffs or IMAX enthusiasts—have experienced a few fly-throughs based on Hubble’s images of nebulae and galaxies.) But with the 25th anniversary, we don’t have to rely on our imaginations or wait for the movie version. In addition to the still image, NASA and STScI have also developed and released animations that begin with a view of the night sky as seen from earth, travel to the location of Westerlund 2 and its surrounding nebula, and then into its sweeping cloud formations. For just a few moments, we float above that fantasy landscape before looking up the tightly clustered stars that the press release likens to a fireworks display.

It’s the fulfillment of the invitation issued by older Hubble images. Instead of stopping at the frontier of the image, we cross over it and indulge our senses with the spectacular scenery. It’s a thrillingly perspective, and it’s only too tempting to forget that we only see like this courtesy of the Hubble Space Telescope and those who translate its data into such sublime views.

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Elizabeth A. Kessler is author of Picturing the Cosmos: Hubble Space Telescope Images and the Astronomical Sublime. She teaches at Stanford University. She has been awarded fellowships by the Smithsonian Institution National Air and Space Museum and Stanford University.

"A gorgeously-illustrated and thoughtful new academic book. An analysis of space pictures unlike anything you've ever read before." —io9


"Readers of this book will never view Hubble images the same way again." —Library Journal

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