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| a chattering or flighty, light-headed person. |
| a children's mummer's parade, as on the Fourth of July, with prizes for the best costumes. |
| X-ray astronomy | |
| —n | |
| the branch of astronomy concerned with the detection and measurement of X-rays emitted by certain celestial bodies. As X-rays are absorbed by the atmosphere, satellites and rockets are used | |
| x-ray astronomy
The study of celestial objects by measurement of the x-rays they emit. Because the Earth's atmosphere absorbs x-rays, x-ray detectors are usually carried into space on satellites. X-rays are emitted by high-energy objects such as active galactic nuclei, supernova remnants, x-ray binary stars, neutron stars, and the regions around black holes. Objects which do not produce their own x-rays can reflect radiation from nearby stars, making it possible to study the objects using x-ray astronomy; one notable example of this is the analysis of solar x-rays reflected by the Moon. |