The Hubble Space Telescope, which was launched in 1990 and is still in use, has examined the universe mostly at optical and ultraviolet wavelengths.

哈勃太空望远镜于1990年发射，目前仍在使用中，主要在光学和紫外线波长下对宇宙进行了探测。

This shift in wavelengths is known as redshift and the result is that the most distant objects emitting visible light are invisible to telescopes tuned to optical wavelengths.

这种波长的偏移被称为红移，其结果是发射可见光的最远物体对于调谐到光学波长的望远镜是不可见的。