Space factStars
The Pleiades, also called the Seven Sisters, is an open star cluster: a group of stars that formed together from one cloud of gas. Measurements by the Hubble Space Telescope put it about 440 light-years from Earth.
A light-year is the distance light travels in one year, so the light you see from the Pleiades left the cluster about 440 years ago. The distance comes from Hubble’s Fine Guidance Sensors, which refined earlier estimates of how far away the cluster sits. ESA/Hubble’s object data rounds the same distance to 450 light-years, so treat the figure as approximate.
440 light-years
Distance to the Pleiades star cluster