Stars aren't supposed to simply disappear, yet countless bright objects that once appeared in the sky in the 1950s no longer do.
To try to solve the mystery, scientists have turned to a growing field known as citizen science, in which everyday individuals of all ages around the globe can take part in research projects that aim to answer real scientific questions about our surroundings, be it on Earth or in space. The Vanishing & Appearing Sources During a Century of Observations (VASCO) citizen science project, which began in 2017, dives into the archives to see how the stars are changing.
"In the citizen science project, we compare images from the 1950s with modern images of the sky," Beatriz Villarroel, the principal investigator of the VASCO project, an astrophysicist at the Nordic Institute for Theoretical Physics in Sweden, and lead author on a new paper describing the project, told Space.com in an email. "The ultimate goal is to identify an object that is clearly visible in several old images, but no longer visible today."
So volunteers with the project are examining 150,000 candidate "vanishing stars" that come from a 2020 study (opens in new tab) to see whether objects in the 1950s images can be found in modern images. The project has examined 15,593 candidate image pairs within the data, or approximately 10% of all the candidates, and have identified 798 objects they classify as "vanished."
The "vanished" stars might turn out to be anything from a flaring star or a supernova to the afterglow of a gamma-ray burst.
The research also contributes to the search for extraterrestrial intelligence, or SETI, as well, according to Jamal Mimouni, an astrophysicist at the University of Constantine 1 in Algeria and a co-author on the paper, who noted that traditionally, SETI has been led by scientists who focus on radio astronomy. VASCO takes a different approach, considering "vanishing stars" a potential sign of advanced civilizations.
"It may be said to be another twist to SETI," he told Space.com in an email. The search comes closer to home, as well, he said. "We are also interested in searching for ET artifacts in orbit around the Earth, by looking for fast solar reflections (glints) from satellites and space debris in pre-Sputnik images."
And the VASCO project isn't only for adults. An off-shoot project, VASCO-Kids, allows younger astronomy fans to take part in scientific studies as well.
"The goal of VASCO-Kids is to popularize the global VASCO project around the world targeting pupils and kids of young age in general, and it also aims to use this project as a powerful support for kids' education in astronomy," Echeima Amine-Khodja, a veteran amateur astronomer who recently finished her master's in astrophysics from University Constantine 1 and who has worked with VASCO and VASCO-Kids for two years, told Space.com in an email.
Since VASCO is available to the public, the web interface (opens in new tab) is designed to be user-friendly to allow individuals from all scientific backgrounds to examine images for "vanishing" stars. VASCO-Kids is an example of public engagement for younger audiences who get to use the web interface to assist in the project.
The VASCO citizen science project has already earned some accolades in the scientific community. Villarroel received the L'Oreal-UNESCO's For Women in Science prize in Sweden in 2021 for her work on the VASCO project, and then the L'Oreal-UNESCO's For Women in Science "International Rising Talents" prize in 2022, making her the first Swede to receive the award. Several studies based on VASCO searches have also been either submitted or published in several journals, including The Astronomical Journal, Acta Astronautica and Scientific Reports (opens in new tab).
As VASCO continues, the project looks to improve its methods, including by strengthening the artificial intelligence the project uses and by gathering infrared and optical images of some of the "most interesting candidates."
"Being part of the VASCO citizen science project helps the person to learn more and develop new skills and practice scientific research like a real scientist," Hichem Guergouri, an astrophysicist at the CERIST research institute in Algeria and a co-author of the paper, told Space.com in an email. "The results that we may find from the citizen science project could even lead to some amazing big new discoveries which anyone would love to have their names part of, so I encourage everyone to join the VASCO citizen science project."