Global science

More than a hundred years ago, Edward Charles Pickering, an astronomer at Harvard University in the United States, decided to "take" a picture of the entire night sky, or use thousands of pieces of debris recorded through a telescope to form a complete picture of the night sky. Today, these photos are sealed under thousands of glass negatives at the Harvard Observatory, the earliest detailed record of the universe. Although the idea for the all-sky map was originally put forward by Pickering, the daunting task was mainly accomplished by a group of women known as Harvard computers. Before the advent of computers made up of silicon chips and circuits, scientists in the fields of physics and astronomy used to rely on their hands to deal with complex computing tasks.

"it was up to people to examine the film containing thousands of stars and mark each star on the film," said Daina Bouquin, chief librarian of the Harvard-Smithsonian Astrophysics Center (Harvard-Smithsonian Center for Astrophysics). "it was a group of women who had worked silently for decades to analyze and create the first all-sky map."

The History of Hidden characters

Like the great women in the movie Hidden Figures, Harvard computers maintain the same mysterious identities and perform the same dazzling feats. Together, women, represented by Henrietta Swan Leavitt and Annie Jump Cannon, have made accurate observations of the trajectory and brightness of stars for the first time. These data construct today's understanding of the basic structure of the universe.

"between the end of the 18th century and the beginning of the 19th century, astronomy underwent a great change," Bouquin said. "our task has shifted from recording and describing the universe to understanding and discussing the physics of the universe." Bouquin is now leading the PHaEDRA project. The goal of the project is to translate years of work of Harvard computer into electronic data. But these records are so large for researchers that the project employs thousands of volunteers to comb through and analyze these astronomical observations. No matter where you are in the world, as long as you have a computer, you can participate in this research.

The volunteers' task was to add notes from the previous year's obscure notepad to NASA's online archives. Scientists today are still exploring the problems in these historical records. The work started by Harvard computer continues to this day.

The fossil record of the universe

Although astronomers have gradually deepened their understanding of stars, planets and galaxies, humans still know nothing about many fields. The universe is still slowly evolving, so starry records from a hundred years ago can provide observations and comparisons for astronomers today. "it's like you're going to do archaeological research, but you don't have a fossil record on hand," Bouquin said. These comparisons are based on the fossil records you need. "

At present, the work of Harvard computer is still locked in thousands of notes kept by the Harvard Observatory. These notes, a collection of decades of work, are filled with measurements and detailed labels of each glass negative, indicating the position, motion and properties of each star. PHaEDRA plans to convert these records into searchable electronic data to promote future astronomical research.

Citizen scientists are helping PHaEDRA to turn these handwritten notes into night sky records from more than a century ago for astronomers. This work is very important. This is because most of our understanding of the universe comes from observing the trajectories of stars. For astronomers, the older the records, the more they can learn.

Bouquin says the plan is now nearly halfway through. The project team has uploaded some of the data to the NASA Astrophysical data system (Astrophysics Data System), a large database created by astronomers and accessible to all scientists.

Cecilia Payne-Gaposchkin, another member of the Harvard computer, studied the spectrum of stars-the wavelengths of light emitted by stars. Her observations helped astronomers realize that stars are mostly made of hydrogen and helium. Before that, astronomers usually thought that the composition of stars was consistent with that of Earth.

"many of them have done very good work," Bouquin said. "it is wrong to erase their exploits." What is almost forgotten along with these "Harvard computer" observations are fleeting traces of history. The volunteers found many illustrations, notes and postcards in the corners of the old notebooks, which are all proof of the real existence of these outstanding women. Bouquin says volunteers on the PHaeDRA program know how to remove this personal information and let us know about the objective achievements of Harvard computers.

Without the efforts of modern citizen scientists, the valuable work of these female astronomical pioneers might have been lost in history forever. As historical records are restored page after page, these women who act as "computers" for astronomy and their discoveries are back in front of people.