What does a complete blood count measure? A CBC measures the amount of 3 types of cells in your blood: White blood cell count. A white blood cell count, also called a leukocyte count, measures the total number of white blood cells in a sample of blood.
In the umbra, the light from the Sun is completely blocked by the Earth. Our lunar observer would see a total solar eclipse; we see the Moon darkened, but glowing a dull red from light scattered by the Earth's atmosphere.
Solar eclipses occur only at a new moon, when the moon passes between the earth and the sun: the moon is entirely backlit and so it's visible only as a shadow. (You can actually see it a very little bit due to earthshine, the light reflected by the earth, onto the moon, and then back.)