2025年10月17日
艾达与达克堤利: 小行星与卫星
影像提供: NASA, JPL, Galileo Mission
说明: 这颗小行星有一颗卫星。1993年，伽利略号探测器在前往探索木星系统的途中，于其漫长的星际航行中遇见并拍摄了两颗小行星。它拍摄的第二颗小行星，艾达（243 Ida），被发现拥有一颗卫星。这颗微小的卫星名为达克堤利（Dactyl或称为艾卫），直径仅约1.6公里，在影像中可见于右侧的小点。相比之下，艾达要大得多，长约60公里，宽25公里。事实上，达克堤利是人类首次发现的小行星卫星。然而现在，已知许多小行星都有卫星。小行星名称Ida和Dactyl取自希腊神话。
明日的图片: 3D
Due to the lapse in federal government funding, NASA is not updating APOD website. We sincerely regret this inconvenience.
由于美国联邦政府资金中断，NASA目前暂停更新APOD网站。对此带来的不便，我们深感抱歉。
英文原文:
Explanation: This asteroid has a moon. The robot spacecraft Galileo enroute to explore the Jovian system in 1993, encountered and photographed two asteroids during its long interplanetary voyage. The second minor planet it photographed, 243 Ida , was discovered to have a moon. The tiny moon, named Dactyl , is only about 1.6 kilometers across and seen as a small dot to the right in the image . In contrast, Ida is much larger, measuring about 60 kilometers long and 25 km wide. In fact, Dactyl is the first moon of an asteroid ever discovered. But now many asteroids are known to have moons. Minor planet names Ida and Dactyl were taken from Greek mythology.
