Description: 有质量的物体会使经过其引力影响范围附近的光线发生弯曲。爱因斯坦的广义相对论预言了这种效应，并在 1919 年日食期间首次被观测到，测量发现太阳附近几颗恒星发出的星光发生了弯曲。引力透镜作用在质量非常大的物体上最为明显，如星系或星系团。如果地球上的观测者正在观测一个光线被（"透镜"）弯曲的遥远天体，这个天体的成像会出现扭曲。这种扭曲总是意味着光线的（缩小）放大，通常能让我们更好地看到暗淡的背景天体。当透镜有足够的质量集中在一个小角度区域时，同一背景物体就会产生多个图像，每个图像的光线到达观察者的时间都不同。测量这些所谓的 "时间延迟 "是确定银河系外哈勃常数值的最佳方法之一。另一方面，来自透镜的多幅图像可以让我们利用建模分析精确地确定其质量。这是一种非常有用的方法，可以用来寻找星系的质量，特别是星系团的质量。

Related Terms:

• 暗物质
• 银河系
• 星系团
• 超大质量黑洞
• 哈勃参数

Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher
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