Knowra Ultraviolet astronomy Ultraviolet astronomy Ultraviolet astronomy studies celestial objects and phenomena through ultraviolet radiation. Because Earth’s atmosphere absorbs most ultraviolet light, observations generally require instruments above the atmosphere.
Ultraviolet spectrum : The region of electromagnetic radiation with wavelengths shorter than visible light and longer than X-rays. Its wavelength bands determine which ultraviolet phenomena instruments can observe.
Hot stars : Stars with high surface temperatures that emit a large fraction of their radiation at ultraviolet wavelengths. Their ultraviolet spectra constrain stellar temperatures, atmospheres, and evolution.
Sounding rocket : A rocket that carries scientific instruments on a brief suborbital flight before returning to Earth. Rocket flights first carried ultraviolet instruments above the absorbing atmosphere.
Optical astronomy : The study of celestial objects using visible-light radiation. Optical light reaches the ground more readily, while ultraviolet observations usually require space instruments.
Ultraviolet detector : A device that converts ultraviolet photons into measurable electrical signals or recorded images. Ultraviolet-sensitive detectors turn incoming photons into astronomical data.
Interstellar medium : The gas, dust, and energetic particles occupying the space between stars in a galaxy. Ultraviolet absorption lines trace its composition, temperature, and structure.
Orbiting Astronomical Observatory : A series of NASA satellites launched from 1966 to 1972 for observations beyond Earth’s atmosphere. These observatories made ultraviolet astronomy a sustained orbital research program.
X-ray astronomy : The study of celestial objects through X-ray radiation, using instruments above Earth’s absorbing atmosphere. X-rays trace more energetic emission than ultraviolet light and require different detectors.
Spectroscopy : The study of matter through its interaction with electromagnetic radiation as a function of wavelength. Ultraviolet spectra reveal temperatures, chemical abundances, and motions in celestial sources.
Stellar winds : Streams of charged particles flowing outward from stars into surrounding space. Ultraviolet spectral lines reveal wind speeds and mass loss from hot stars.
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