Astronomers have discovered the closest black hole to Earth to date, using data from the European Space Agency’s (ESA) Gaia space probe. This new method based on the properties of binary star systems is expected to detect more dormant black holes in the future. In June 2022, ESA published the third complete Gaia observational dataset (Gaia DR3). Based on selection criteria for a system of luminous stars and massive invisible companions orbiting each other, the researchers identified six candidates. When two objects orbit each other as a binary star system, each of them usually has an elliptical orbit. Gaia DR3 contains partial data for 168,065 such ellipses. Through orbital calculations and fitting, the researchers found the object “Gaia BH1” that best matched the known data. The results of the study revealed that Gaia BH1 is a system with a sun-like star and an invisible object with an orbital period of 185.6 days. This invisible object has about 10 times the mass of the Sun. The distance between the star and its companion is about the same as the average distance between the Earth and the Sun. If Gaia BH1 were another star, it would have to be much brighter than its companion. Conversely, neither Gaia’s data nor subsequent observations showed light from the second star. Therefore, this invisible object is considered a black hole.
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