The new findings are based on 11 years of observations of Gliese 581 using the HIRES spectrometer on the Keck I Telescope at the W. M. Keck Observatory in Hawaii. The spectrometer allows precise measurements of a star's radial velocity (its motion along the line of sight from Earth), which can reveal the presence of planets. HIRES (the High Resolution Echelle Spectrometer), designed by Vogt, is the largest and most mechanically complex of the Keck's main instruments. HIRES breaks up incoming starlight into its component colors to measure the precise intensity of each of thousands of color channels. Its spectral capabilities have resulted in many breakthrough discoveries, such as the detection of planets outside our solar system and direct evidence for a model of the Big Bang theory.