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| | Surface Brightness |
 | | The concept of surface brightness is crucial for urban and suburban observing, and indeed, for deep-sky observing of all kinds. |
 | | When an object is twice as far away, it appears one quarter as bright; however, it also appears to be half as big, or one quarter the area, so the surface brightness, or brightness per unit area, remains the same. |
 | | To make matters worse, amateur astronomers frequently use the term brightness to mean both integrated brightness and surface brightness in the same paragraph, and also often use it to denote the subjective impression of brightness, which depends both on surface brightness and on integrated brightness. |
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