Side by side photographic glass plates and images by James Webb show how telescope technology has evolved since the 19th century

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

Today, mankind’s most advanced telescopes enable astronomers to see far 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 cutting-edge technology for telescopes like Webb, they cataloged the Universe with an early form of glass plate photography.

For nearly 100 years, beginning in the late 1800s and ending in the 1980s, astronomers used photographic glass plates about the thickness of window panes to capture light from stars, star clusters, and other celestial objects. To map the sky, they laboriously positioned a telescope on an object by hand over a long period of time. The recordings were made on glass plates coated with light-sensitive emulsions, which astronomers later develop like film in a darkroom.

Astronomers meticulously studied these clear panes of glass, which were negatives dotted with dark smudges of stars and other cosmic objects.

The resulting plates — the earliest photographic atlases of the sky — allowed astronomers to create a classification system for stellar objects that ultimately served as the sky’s record for almost a century.

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

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

In comparison, images of the same cosmic objects captured on old-fashioned photographic plates and by Webb show how far our ability to capture and study the cosmos has progressed.

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

Harvard College Observatory has a collection of more than half a million glass plates, including one taken in Arequipa, Peru, in 1896 with a 24-inch telescope that captured the nebula faintly against a larger section of 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 Harvard College Observatory, told Insider that Webb’s magnification capability is 100 times better than what astronomers could capture on photographic glass plates.

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

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

Early images of the gas giant show faint cloud bands in the upper left and the Great Red Spot, a violent storm that has been swirling for centuries. According to Carver, the glass plate image was taken at Wilson’s Peak, Nevada, in 1889 with a 13-inch telescope.

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

The glass plate image of Jupiter in the upper left is from the Carnegie Institute, which maintains a collection of 250,000 glass plates from Las Campanas Observatory in Chile and Mount Wilson and Palomar Observatories in Calfornia.

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

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

According to Giardino, one of the main reasons Webb is able to get such sharp images of the galaxy group is its ability to detect infrared light. Webb’s image is a giant mosaic of nearly 1,000 images, containing more than 150 million pixels, according to NASA.

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