The Hubble Space Telescope (HST) was launched into low Earth orbit in 1990 and remains in operation. The HST is named after the astronomer Edwin Hubble, and is one of NASA's Great Observatories. Hubble's orbit outside the distortion of Earth's atmosphere allows it to take extremely high-resolution images, with substantially lower background light than ground-based telescopes. Hubble has recorded some of the most detailed visible light images ever, allowing a deep view into space and time. Many Hubble observations have led to breakthroughs in astrophysics, such as accurately determining the rate of expansion of the universe.