ESA launched its Hipparcos mission on 8 August, 1989. Hipparcos pinpointed the positions of one hundred thousand stars. It turned slowly on its axis and repeatedly scanned right around the sky on different slants. Hipparcos measured angles between widely separated stars, and recorded their brightness, which were often variable from one visit to the next. Each star selected for study was visited about 100 times over four years. Reference: esa.int/Our_Activities/Space_Science/Hipparcos_factsheet, Retrieved 26 June, 2012
Posted on: Fri, 08 Aug 2014 08:00:00 +0000
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