金星凌日和天文单位：四个世纪以来不断提高的精度
Transits of Venus and the Astronomical Unit: four centuries of increasing precision
摘要：
自第一次天文观测以来，只有七次金星凌日被观测和研究：1639年，1761-69年，1874-82年和2004-12年。测量天文单位一直是研究这一罕见现象的主要目标之一，也是确定行星大气及其性质、了解黑滴现象和测量太阳直径的主要目标之一。1639年J·霍罗克斯观测到的凌日被更详细地介绍。
英文摘要：
Only seven transits of Venus have been observed and studied up to now since the first astronomical observations with the telescope: 1639, 1761-69, 1874-82 and 2004-12. The measurement of the Astronomical Unit has been one of the main goal of the study of this rare phenomenon, as well as the identification of the planetary atmosphere and its properties, the understanding of the black drop phenomenon and the measurement of the solar diameter. The transit of 1639 observed by J. Horrocks is presented in more detail.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
