This image taken by the space probe Galileo at a distance of 2, 400 km captured IDA and its tiny companion, dactyl.

这幅照片由太空探测器伽利略号离小行星2,400公里处拍摄，依达与其卫星达克图清晰可见。

youdao

That is good enough to see shifts caused if a star's companion is another star, but it cannot detect the tiny wobbles caused by orbiting planets.

ECONOMIST: A roadmap for planet-hunting