Side-by-side photographic glass plates and images by James Webb show how telescope technology has evolved since the 1800s

• In the 19th and early 20th centuries, astronomers cataloged the universe on glass photographic plates.
• Astronomers are still studying these plates, which serve as a record of the sky spanning nearly 100 years.
• Compared to faint objects stamped on plates, images from the James Webb Space Telescope show dramatic improvements in telescope technology.

Today, mankind’s most advanced telescopes allow astronomers to peer deep into the universe. NASA’s newest and most powerful astronomical workhorse, the James Webb Space Telescope, has been providing sharp images of the most distant objects in the universe since July.

Long before astronomers developed the advanced technology for telescopes like Webb, they cataloged the universe using an early form of glass plate photography.

For nearly 100 years, beginning in the late 19th century and well into the 1980s, astronomers used glass photographic plates about as thick as window panes to capture light from stars, clusters, and stars. other celestial objects. To map the sky, they painstakingly hand-positioned a telescope over an object for an extended period of time. Exposures were made on glass plates coated with photosensitive emulsions, with astronomers later developing the plates like film in a darkroom.

Astronomers meticulously studied these sheets of transparent glass, which were negatives, dotted with dark spots of stars and other cosmic objects.

Acc. 90-105 – Science Service, Archives, 1920s-1970s, Smithsonian Institution Archives

The resulting plates – the first photographic atlases of the sky – allowed astronomers to establish a classification system for stellar objects, which eventually served as a record of the sky spanning nearly a century.

Astronomers still use these transparent plates because they provide insight into the stellar past and the evolution of our universe. Compared to Webb’s infrared images, photographic plates of the same parts of the night sky show how technological developments have led to clearer and deeper views of the cosmos.

“We’ve gone from the human eye to photographic plates, and now to electronic devices, in the case of the James Webb Space Telescope,” Giovanna Giardino, Webb scientist at the European Space Agency, told Insider. “Leaps in technology have allowed us to have larger telescopes, which can see fainter objects,” Giardino added.

Compared side by side, images of the same cosmic objects taken on old-fashioned photographic plates and by Webb show just how far our ability to capture and study the cosmos has come.

Harvard College Observatory, Collection of Astronomical Photographic Glass Plates

The Carina Nebula, an assembly of gas and young stars, 7,600 light-years away and four times larger than the Orion Nebula, was first discovered in 1752. It is a vast region of formation of stars and is home to extremely massive young stars, including Eta Carinae – a volatile system containing two massive stars that orbit closely around each other.

The Harvard College Observatory has a collection of more than half a million glass plates, including one taken in Arequipa, Peru in 1896 using a 24-inch telescope that faintly captured the nebula over a larger part of the sky.

In July, Webb also captured an image of the Carina Nebula, but there is a dramatic difference in scale between the two images. Nico Carver, a librarian at the Harvard College Observatory, told Insider that Webb’s magnification ability is 100 times better than what astronomers could capture in photographic glass plates.

“Webb is a marvel of technology. It’s very advanced instrumentation,” Giardino said, adding that Webb’s ability was made possible by advances in telescope technology over time. “Science is always based on what we know,” Giardino said.

Harvard College Observatory, Collection of Astronomical Photographic Glass Plates

Galileo Galilei made the first detailed observations of the planet in 1610 with a small telescope.

The first images of the gas giant show, top left, show faint bands of cloud and the Great Red Spot, a huge storm that has been swirling around for centuries. The image of the glass plate was taken in 1889 at Wilson’s Peak, Nevada, using a 13-inch telescope, according to Carver.

Courtesy of the Carnegie Institute for Science; NASA, ESA, Jupiter ERS team; image processing by Judy Schmidt

Recent images from Webb, captured in July and released in August, show the planet’s turbulent atmosphere and the Great Red Spot in remarkable detail. The telescope also spotted Jupiter’s thin rings, made up of dust particles from debris, and auroras visible at Jupiter’s north and south poles.

The image of Jupiter’s glass plate, top left, is from the Carnegie Institute, which maintains a collection of 250,000 glass plates from the Las Campanas Observatory in Chile and the observatories of Mount Wilson and from Palomar, California.

Courtesy of Carnegie Institute for Science/NASA, ESA, CSA and STScI

Stephan’s Quintet, a set of five galaxies located 290 million light-years from Earth in the constellation Pegasus, was first discovered in 1877. Four of the five galaxies interact gravitationally in a slow-motion merger. The fifth galaxy is much closer to Earth, about 40 million light-years away.

The quintuple is faintly visible in the image of the glass plate taken in 1974, top left. On July 12, when Webb released his first batch of images, one captured Stephan’s Quintet in unprecedented detail.

Harvard College Observatory, Collection of Astronomical Photographic Glass Plates

According to Giardino, one of the main reasons Webb can take such sharp photos of the cluster of galaxies is because of its ability to detect infrared light. Webb’s image is a huge mosaic of nearly 1,000 images, according to NASA, containing more than 150 million pixels.

More pixels allow astronomers to capture higher-resolution views of the cosmos, according to Giardino. “It was a huge improvement,” she said.