Posted by A.S. on March 3, 2014, 5:25 p.m.
The actual distance to the Pleiades - the High Precision Parallax Collecting Satellite (Hipparcos) measured the parallax of the Pleiades and determined a distance of 385 light years. This was significantly different from other measurements made by means of actual to apparent brightness measurement or absolute magnitude. The anomaly was due to a systematic bias in the Hipparcos data when it comes to star clusters; the Hipparcos results for clusters are consistently closer than they should be.