Meanwhile, different measurement methods have produced conflicting results throughout the years. Observations based on nearby cosmic objects like Cepheid variable stars and supernovae suggest a faster expansion rate. This corresponds to a younger Universe of roughly 13 billion years. <\/p>\n
In contrast, measurements based on the cosmic microwave background, the faint afterglow of the Big Bang<\/a>, indicate a slower expansion, as well as a slightly older Universe of about 14 billion years. <\/p>\n \u201cMeasuring the age of stars<\/a> is, in itself, a complex challenge, but we now live in an era in which the quantity and quality of available data allow us to achieve unprecedented precision and, for the first time, statistically significant results,\u201d Tomasetti said.<\/p>\n To address the challenge, the research team placed their focus on the ages of the oldest stars in the galaxy. Because the Universe cannot be younger than the stars it contains, accurately measuring the ages of the oldest stars in the Milky Way can provide a robust lower limit on the age of the Universe.<\/p>\n Clues from ancient stars<\/p>\n For the project, the team utilized an existing catalogue of stellar ages developed at AIP, which contains age estimates for over 200,000 stars in the Milky Way<\/a>. Data from the European Space Agency\u2019s Gaia mission provided precise measurements of stellar distances and spectra.<\/p>\n This information made it possible for the scientists to determine stellar properties with unprecedented accuracy. The team utilized the dataset to select a carefully vetted sample of the oldest stars with the most reliable age measurements. <\/p>\n They prioritized quality over quantity, and filtered out objects that might distort the results. The final sample included about 100 ancient stars, whose ages were determined using the StarHorse computational framework.<\/p>\n Cristina Chiappini, PhD, a senior scientist at AIP, noted that the Gaia mission has effectively turned the Milky Way into a near-field cosmology lab. \u201cWe can now estimate stellar ages with unprecedented precision,\u201d Chiappini said. <\/p>\n \u201cThe next breakthrough will be accuracy, anchoring the Galactic timeline with far greater certainty,\u201d she concluded in a press release<\/a>. \u201cThe HAYDN mission concept, with AIP participation, aims to provide that decisive step.\u201d<\/p>\n Future data releases from Gaia are expected to further improve age estimates and could refine measurements of both the Universe\u2019s age and the Hubble constant.<\/p>\n![\"\"](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2026\/03\/Z22.jpg\" "\\"200,000")
The value of the Hubble constant is one of the most debated questions in modern cosmology.
Credit: Elena Tomasetti<\/a><\/p>\n