宇宙微波背景

现存最古老的光，在大爆炸后 38 万年宇宙首次变得透明时发出。此后宇宙膨胀已把它的来源带到 450 亿光年之外。地图来自 Planck；太阳周围的球壳就是那道光的来处，再远处什么也看不见。从外面看，这个球体是我们自身视界的图像，而不是一个地方。

当前距离

453亿 ly

光发出于

138亿年前

温度

2.725 K

地图

ESA Planck, SMICA

The cosmic microwave background, or relic radiation, is microwave radiation that fills all space in the observable universe. With a standard optical telescope, the background space between stars and galaxies is almost completely dark. However, a sufficiently sensitive radio telescope detects a faint background glow that is almost uniform and is not associated with any star, galaxy, or other object.

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