It demonstrates that an indirect method sensitive to a planet’s gravitational pull can tell you where to look and exactly when to look for direct imaging. “This is sort of a test run for the kind of strategy we need to be able to image an earth. Such a planet will be much closer to its star and so will spend a large amount of time either in front or behind that star, making it impossible to see. Finding a planet like our own remains an ultimate goal for astronomers. Ultimately, this combined approach will allow us to target other Earths. This is because Gaia’s fourth data release (DR4), which will be based on 5.5 years of data (nearly double the baseline for DR3) will make it much easier to spot which stars are wobbling. This method of targeting stars for exoplanet discovery is going to accelerate. Gaia’s stellar motion for the next 400 thousand years From this database, the team identified a number of stars that appeared to change position on the night sky in a way that suggested they were each orbited by a giant planet. Measuring the position of a star on the sky is known as astrometry. This catalogue combines data from Gaia with that from ESA’s previous star mapping mission, Hipparcos, to provide a 25-year baseline for comparing the precise positions of stars. In particular, they used the Hipparcos-Gaia Catalogue of Accelerations. In his attempt to load the dice in favour of success, he and colleagues turned to the Gaia mission to look for stars that literally wobbled on the sky. “We wanted a different strategy,” says Thayne Currie, National Astronomical Observatory of Japan (NAOJ), Hilo, Hawaii and the University of Texas-San Antonio. ![]() Out of hundreds of stars surveyed in this way, only a handful have yielded planets. Most direct imaging searches are ‘blind’, meaning that they simply target stars based on their age and distance and hope that a planet will be seen. Because nature does not make many of these types of planets, astronomers would like to know exactly where to look.
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