- Also called twinkling, variation in the brightness,
wavelength, and mean position of stars caused by turbulence high in
Earth's atmosphere which changes irs refractive
index. Planets don't exhibit this because the scintillations from
different points on the surface are not in phase,
and the fluctuations are lost in the general illumination. For astronomical
purposes, the inconvenience of the effects of scintillation is reduced
by siting observatories at high altitudes and through the use of adaptive
optics, and is almost entirely avoided by using telescopes carried
by balloons, rockets, or artificial satellites.
- Rapid changes in the detected intensity of radiation from compact
cosmic radio sources due to disturbances in ionized gas at some point
between the source and Earth's surface (usually in Earth's upper atmosphere).