English: Gemini North, one half of the international Gemini Observatory, a Program of NSF’s NOIRLab, uses a laser beam traveling through Earth’s atmosphere to adjust its adaptive optics. Like many large research telescopes today, Gemini North uses adaptive optics — bending its mirrors to compensate for atmospheric turbulence or “seeing”, which can blur the images of distant objects like stars and galaxies. The laser beam, seen here as a pink-orange stripe on the sky, travels into the upper atmosphere where it creates a bright spot of light that provides a reference point for the telescope to follow, and correct for, the atmospheric turbulence. This long-exposure photograph shows the laser tracking its target near the zenith, appearing to paint the sky with light. The stars appear as trails as they revolve around the north celestial pole during the long exposure.