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| Observing the Moon ： ウィキペディア英語版 |
Lunar observation
The Moon is Earth's largest natural satellite and the nearest major celestial object. Observing the Moon can be accomplished by using a variety of instruments ranging from the naked eye to large telescopes. For most people, the Moon is the only celestial object upon which surface features can be discerned with the naked eye (some people with good eyesight can see large sunspots on the surface of the Sun using handheld solar filters).
==Optimal viewing times==
Contrary to popular belief, the Moon should ideally not be viewed at its full phase. During a full moon, rays of sunlight are hitting the visible portion of the moon perpendicular to the surface. As a result, there is less surface detail visible during a full moon than during other phases (such as the quarter and crescent phases) when sunlight hits the Moon at a much shallower angle. In addition, the brightness of a full moon as compared to a phase where a smaller percentage of the surface is illuminated tends to wash out substantial amounts of detail and can actually leave an afterimage on an observer's eye that can persist for several minutes. First quarter (six to nine days past new moon) is generally considered the best time to observe the Moon for backyard stargazers. It is true that if one views the Moon during this time, a smaller percentage of the surface will be seen at a time, however the detail will be vastly more impressive. Shadows and detail are most pronounced along the "terminator", the dividing line between the illuminated (day side) and dark (night side) of the Moon.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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