每日一天文图（Astronomy Picture of the Day，APOD）网站是美国国家航空暨太空总署与密西根科技大学（MTU）提供的服务，经由网站，每天提供一张我们宇宙不同的影像或图片，并由专业的天文学家写上一份扼要的说明为其特色。照片呈现时不需要特别注明确实的拍摄日期，图像有时也会重复。但是，图片和描述经常与天文或太空探测的时事有关，图像可以是一张相片、在不同波长下拍摄的假色图，或是艺术家的构想。从1995年6月16日起的第一张开始，过去的影像都被APOD保存着。美国国家航空暨太空总署、国家科学基金会和密西根科技大学都主动的支持这个网站。图样的作者是自然人或不属于美国国家航空暨太空总署，因此APOD的影样不同于美国国家航空暨太空总署其它的影像集，经常只是拥有版权的。在**的国立成功大学物理系取得正体中文版的翻译授权，每日进行翻译工作。

Astronomy Picture of the Day (APOD) is a website provided by NASA and Michigan Technological University (MTU). According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer." The photograph does not necessarily correspond to a celestial event on the exact day that it is displayed, and images are sometimes repeated. However, the pictures and descriptions often relate to current events in astronomy and space exploration. The text has several hyperlinks to more pictures and websites for more information. The images are either visible spectrum photographs, images taken at non-visible wavelengths and displayed with false colors, video footage, animations, artist’s conceptions, or micrographs that relate to space or cosmology. Past images are stored in the APOD Archive, with the first image appearing on June 16, 1995. This initiative has received support from NASA, the National Science Foundation, and MTU. The images are sometimes authored by people or organizations outside NASA, and therefore APOD images are often copyrighted, unlike many other NASA image galleries.