What is the term for the darker, central part of a shadow from which the light source cannot be seen?

What is the term for the darker, central part of a shadow from which the light source cannot be seen?

• A. Umbra
• B. Penumbra
• C. Shadow
• D. Eclipse

Answer: (A)

The darkest, central part of a shadow where the light source cannot be seen is called the umbra. This region forms because the object blocks all rays from the light source, so no direct light reaches there. In a solar eclipse, for example, observers inside the Moon’s umbra would see the Sun completely blocked. Surrounding the umbra is the penumbra, a lighter area where only part of the light source is blocked, so the shadow is not as dark. Outside these regions is just a broader shadow where the Sun is visible again. The term shadow refers to any dark region caused by blocking light, and an eclipse is the event of one body moving into the shadow of another.

The darkest, central part of a shadow where the light source cannot be seen is called the umbra. This region forms because the object blocks all rays from the light source, so no direct light reaches there. In a solar eclipse, for example, observers inside the Moon’s umbra would see the Sun completely blocked. Surrounding the umbra is the penumbra, a lighter area where only part of the light source is blocked, so the shadow is not as dark. Outside these regions is just a broader shadow where the Sun is visible again. The term shadow refers to any dark region caused by blocking light, and an eclipse is the event of one body moving into the shadow of another.