the branch of astronomy that studies celestial objects by means of the x-rays emitted by them.
When X Always = 10
Roman numerals are a collection of symbols that make up the number system that was used by the ancient Romans. Today, Roman numerals are more commonly used in titles, to number parts of works, in music theory, and on clock faces. Where do you see Roman numerals most often? The Symbols The Roman numeral system uses only seven symbols: I, V, X, L, C, D, …
The Truth Is In The X-Files
Read more in this article about some frequently asked questions and fun facts related to our definitions.
Compare x-ray(def 1b).
Origin of x-ray astronomy
First recorded in 1960–65
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
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
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.