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, the James Webb Space Telescope images show dramatic improvements in telescope technology.
Today, mankind’s most advanced telescopes allow astronomers to peer 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 the cutting-edge technology for telescopes like Webb, they recorded the universe using an early form of photography on glass plates.
For nearly 100 hundred years, beginning in the late 19th century and lasting until the 1980s, astronomers used glass photographic plates about the thickness of window panes to capture light from stars, clusters, and other celestial objects. To map the sky, they manually placed a telescope on an object for a long time. The exposures were made on glass plates coated with photosensitive emulsions, with the astronomers later developing the plates like film in a darkroom.
Astronomers carefully studied these transparent glass sheets, which were negatives, dotted with dark spots from stars and other cosmic objects.
The resulting plates—the first photographic atlases of the sky—allowed astronomers to create a classification system for stellar objects that eventually served as a record of the sky spanning nearly a century.
Astronomers still use these transparent plates as they provide information about the stellar past and the evolution of our universe. Compared to Webb’s infrared images, the photographic plates of the same parts of the night sky show how advances in technology have led to clearer and deeper views of the universe.
“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, a Webb scientist at the European Space Agency, told Insider. “Technological leaps 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 universe has come.
The Carina Nebula, a collection 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 star-forming region and home to young, extremely massive stars, including of Eta Carinae — a volatile system containing two massive stars that orbit each other closely.
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 in a larger patch 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 the Harvard College Observatory, told Insider that Webb’s magnification is 100 times better than what astronomers could capture on photographic glass plates.
“Webb is a marvel of technology. It’s a very advanced instrument,” 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.
Galileo Galilei made the first detailed observations of the planet in 1610 with a small telescope.
The first images of the gas giant show, upper left, faint bands of clouds and the Great Red Spot, a massive storm that has been swirling 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.
Recent images from Webb, taken 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 of dust particles from debris, and visible auroras at Jupiter’s north and south poles.
The glass plate image of Jupiter, top left, comes from the Carnegie Institution, which maintains a collection of 250,000 glass plates taken from the Las Campanas Observatory in Chile and the Mount Wilson and Palomar observatories in California.
Stephan’s Quintet, a collection of five galaxies 290 million light-years from Earth in the constellation Pegasus, was first discovered in 1877. Four of the five galaxies are gravitationally interacting in a slow-motion merger. The fifth galaxy is much closer to Earth, about 40 million light-years away.
The quintet is faintly visible in the plate glass image taken in 1974, upper left. On July 12, when Webb released his first batch of images, one captured the Stephan Quintet in unprecedented detail.
According to Giardino, one of the main reasons Webb is able to take such sharp pictures of the galaxy group is because of its ability to detect infrared light. The Webb image is a massive 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 universe, according to Giardino. “That was a huge improvement,” he said.
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