Harvard College Observatory, Astronomical Photographic Glass Plate Collection
- In the 19th and early 20th centuries, astronomers catalogued the universe on glass photographic plates.
- Astronomers still study these plates, which serve as record of the sky spanning almost 100 years.
- Compared to faint objects stamped on plates, the James Webb Space Telescope's images show dramatic improvements in telescope technology.
Today, humanity'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 delivering 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 catalogued the universe using an early form of photography on glass plates.
For almost 100 hundred years, starting in the late 19th century and lasting until the 1980s, astronomers used glass photographic plates about as thick as window panes to capture light from stars, clusters, and other celestial objects. To map the sky, they painstakingly hand-positioned a telescope on an object for a long period of time. The 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 clear glass sheets, which were negatives, scattered with dark specks of stars and other cosmic objects.
Acc. 90-105 - Science Service, Records, 1920s-1970s, Smithsonian Institution Archives
The resulting plates — the earliest photographic atlases of the sky — allowed astronomers to establish a classification system for stellar objects, which ultimately served as record of the sky spanning almost a century.
Astronomers are still using these see-through plates, since they provide insight into the stellar past and the evolution of our universe. Compared with Webb's infrared images, photographic plates of the same parts of the night sky show how developments in technology led to clearer and deeper views of the cosmos.
"We went 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 jumps have allowed us to have bigger 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 how much our ability to capture and study the cosmos has advanced.
Webb spots the stunning Carina Nebula hidden in field of stars
Harvard College Observatory, Astronomical Photographic Glass Plate Collection
The Carina Nebula, an assemblage of gas and young stars, 7,600 light-years away and four times as large as the Orion Nebula, was first discovered in 1752. It's a vast, star-forming region and home to young, extremely massive stars, including Eta Carinae — a volatile system containing two massive stars that closely orbit 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 against a larger patch of sky.
In July, Webb also captured an image of the Carina Nebula, but there's a dramatic scale difference 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 a very advanced instrumentation," Giardino said, adding that Webb's ability was made possible through advancements in telescope technology over time. "Science is always building on what we know," Giardino said.
Webb took crisp images of Jupiter's turbulent storms, clouds, and light shows
Harvard College Observatory, Astronomical Photographic Glass Plate Collection
Galileo Galilei made the first detailed observations of the planet in 1610 with a small telescope.
Early images of the gas giant show, above left, show faint bands of clouds and the Great Red Spot, an enormous storm that has been swirling for centuries. The glass plate image was taken in 1889 at Wilson's Peak, Nevada, using a 13-inch telescope, according to Carver.
Courtesy of Carnegie Institution for Science; NASA, ESA, Jupiter ERS Team; image processing by Judy Schmidt
Recent images by 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 of dust particles from debris, and visible auroras at Jupiter's northern and southern poles.
The glass plate image of Jupiter, above left, is from the Carnegie Institute, which maintains a collection of 250,000 glass plates taken from the Las Campanas Observatory in Chile and Calfornia's Mount Wilson and Palomar observatories.
Webb's clear views of interacting galaxies offer sharper detail than faint glass plate images
Courtesy of Carnegie Institute for Science/NASA, ESA, CSA, and STScI
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 fivesome is faintly visible in the glass plate image taken in 1974, above left. On July 12, when Webb released its first batch of images, one captured Stephan's Quintet in unprecedented detail.
Harvard College Observatory, Astronomical Photographic Glass Plate Collection
According to Giardino, one of the main reasons Webb can take such sharp pictures of the group of galaxies is because of its ability to detect infrared light. Webb's image is an enormous mosaic of nearly 1,000 images, according to NASA, containing more than 150 million pixels.
More pixels allows astronomers to capture higher-resolution views of the cosmos, according to Giardino. "This was a huge improvement," she said.
from Business Insider https://ift.tt/KXHTIQx
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