X-BandA frequency band of microwave radiation in which radars operate.
X-Ray BackgroundIn solar-terrestrial terms, a daily average background X-ray flux in the 1 to 8 angstrom range.
X-Ray BurstIn solar-terrestrial terms, a temporary enhancement of the X-ray emission of the sun.
X-Ray Flare ClassIn solar-terrestrial terms, rank of a flare based on its X-ray energy output. Flares are classified by the order of magnitude of the peak burst intensity…
X-RaysThe part of the electromagnetic spectrum whose radiation has much greater frequencies and smaller wavelengths than those of ultraviolet radiation.