The Hubble Space Telescope (HST) is a space telescope in low Earth orbit with a 2.4 meter main mirror capable of observing near ultraviolet, visible, and near infrared light. It was launched in 1990 and remains in operation (following five servicing missions) as of 2015.

The Hubble Space Telescope (HST) is a space telescope that was launched into low Earth orbit in 1990, and remains in operation. With a 2.4-meter (7.9 ft) mirror, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared spectra. The telescope is named after the astronomer Edwin Hubble.

Hubble's orbit outside the distortion of Earth's atmosphere allows it to take extremely high-resolution images with negligible background light. 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.

When launched the main mirror of Hubble was ground incorrectly and was therefore unable to focus light properly. The telescope was designed to be serviced by Space Shuttle missions, so in 1993 the first servicing mission installed the Corrective Optics Space Telescope Axial Replacement (COSTAR) to act as "spectacles" to correct the spherical aberration.

When asking questions relating to Hubble observations keep in mind that this is the "Space Exploration" stack exchange. While we will likely try to answer you questions the Astronomy stack exchange may provide better answers depending on the subject of your question.