In astronomy we throw around the term “light-year” seemingly as fast as light itself travels. And yet actually measuring this distance is incredibly tricky. A star’s parallax — its tiny apparent shift once a year caused by our moving viewpoint on Earth — tells its distance more truly than any other method.
Accurate parallaxes of nearby stars form the base of the entire cosmic distance ladder out to the farthest galaxies. It’s a crucial science that’s about to take a giant leap forward. The European Space Agency’s long-awaited Gaia observatory — launched on Dec. 19, 2013 — is now ready to begin its science mission. Continue reading “GAIA is “Go” for Science After a few Minor Hiccups”