Hubble Space Telescope

A space observatory launched in 1990 that observes ultraviolet, visible, and near-infrared light above Earth’s atmosphere. Its long operational life and sharp images have made it a major source of astronomical discoveries.

Low Earth orbit: An orbit around Earth at altitudes from roughly 160 to 2,000 kilometers. Hubble circles Earth in this region, completing an orbit about every 96 minutes.
Hubble Deep Field: A long-exposure image of a small region of sky containing thousands of distant galaxies. This 1995 observation showed how many galaxies occupy even an apparently empty patch of sky.
Lyman Spitzer: An American astrophysicist who advocated placing astronomical telescopes above Earth’s atmosphere. His proposals helped establish the scientific case for a large space telescope.
James Webb Space Telescope: A space observatory optimized for infrared astronomy, launched in 2021. Webb observes longer infrared wavelengths and operates much farther from Earth than Hubble.
Ritchey–Chrétien telescope: A reflecting telescope design that uses hyperbolic primary and secondary mirrors to reduce off-axis optical aberrations. Hubble’s two-mirror optical system uses this design to deliver sharp images across a wide field.
Hubble Ultra-Deep Field: An image assembled from Hubble observations of a small region of sky, revealing galaxies from the early universe. Its exceptionally long exposure pushed Hubble’s view farther back in cosmic time.
Large Space Telescope: A NASA project that developed into the Hubble Space Telescope. Hubble emerged from this long-running effort to place a powerful observatory in orbit.
Chandra X-ray Observatory: A NASA space telescope that observes X-rays from energetic astronomical objects. Chandra complements Hubble by studying high-energy light outside Hubble’s wavelength range.
Wide Field Camera 3: A Hubble instrument that images ultraviolet, visible, and near-infrared light. Installed during the final servicing mission, it expanded Hubble’s imaging capabilities.
Hubble constant: The present-day rate of expansion of the universe, expressed as recession speed per unit distance. Hubble observations of Cepheid stars helped refine measurements of this expansion rate.

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