Optical astronomy

Optical astronomy studies celestial objects through ultraviolet, visible, and infrared light. It uses ground-based and space-based instruments to collect and analyze this radiation.

Optical telescope: An instrument that collects and focuses light from distant objects to produce an image or measurement. Its mirrors or lenses gather the ultraviolet, visible, or infrared light optical astronomers study.
Exoplanet transit: An apparent dip in a star’s brightness when an orbiting planet passes in front of it. Repeated optical brightness dips can reveal a planet’s size and orbital period.
Galileo Galilei: An Italian astronomer and physicist who made telescopic observations that transformed early modern astronomy. His telescope observations of the Moon, Jupiter, and Venus established telescopic astronomy as a powerful method.
Radio astronomy: The study of celestial objects through radio-frequency electromagnetic radiation. Radio waves reveal phenomena and structures that optical observations cannot directly detect.
Charge-coupled device: A semiconductor image sensor that converts incoming photons into electrical signals. CCD cameras record faint optical images with high sensitivity and precision.
Stellar classification: The organization of stars into types based mainly on their spectra and surface temperatures. Optical spectra place stars into classes and indicate their temperatures and evolutionary states.
Isaac Newton: An English physicist and mathematician who developed the reflecting telescope and a theory of gravity. His reflecting telescope design helped overcome chromatic aberration in lens-based instruments.
X-ray astronomy: The study of celestial objects through X-ray radiation. X-rays trace extremely hot and energetic environments, unlike the cooler sources prominent in optical light.
Adaptive optics: A technique that corrects image distortion by rapidly reshaping a telescope mirror. It counteracts atmospheric turbulence that blurs ground-based observations.
Galaxy morphology: The classification of galaxies by their visible structure, such as spiral arms or elliptical shape. Optical images show the structures used to classify galaxies and study their evolution.

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