A lunar eclipse is, in contrary to a solar eclipse, quite common and this happens when the Moon lies in Earths shadow. Three types exist: total, when the Moon crosses entirely within the Earth's umbra,  partial, when the Moon crosses partially into the Earth's umbra and penumbral, when the Moon crosses only the Earth's penumbra.

Interesting to know is that during a total eclipse, the Moon remains visible because of light scattering in the Earth's atmosphere. In this "filter", the red color is dominant, for the same reason as "our sky" turns red when light goes to thicker atmospheric layers during sunsets or sunrises. It remains unpredictable how dark the red colors will turn out and this all depends on how much dust and cloudiness is present in Earth's atmosphere. In case of major volcanic eruptions, a lot dust is blown in our atmosphere resulting in very dark colors on the Moon.     

The picture shows a total lunar eclipse which began at 2344LT on March 3 and ended at 0058LT on March 4. On one side (this case the left) more scattered light passes through Earth's atmosphere reaching the Moon.