That means the moon was completely in the shadow of the Earth.

它意味着月球完全处于地球的阴影之下。

For example, when there's a lunar eclipse, the shadow of the Earth is cast on the Moon.

例如，当月食发生时，地球的影子会投射到月球上。

What it was a total lunar eclipse, what does that mean? That means the moon was completely in the shadow of the Earth.

什么是月全食，那意味着什么？这意味着月球完全处于地球的阴影之下。

So something like the sun that's bigger than the Earth and is able to cast a shadow of the Earth on the moon can actually show you the shape of the Earth.

像太阳这种比地球大的东西，能够在月球上投射地球的阴影，从而真实地给你展示地球的形状。

During a total lunar eclipse the shadow of the Earth will cross gradually over the surface of the moon, but once the moon has entered the umbra, completly blocking the sun's light, the moon will often look reddish.

在月食的整个过程中，地球阴影会逐渐扫过月球表面，但是一旦月球进入地球暗影完全接收不到太阳光，月球通常看起来会是淡红色。