What distinguishes an occulting light?

An occulting light is characterized by a specific pattern where the duration of light exceeds the duration of darkness. This means that when observing this type of light, the intervals of illumination are longer than the intervals of darkness, which makes it a unique signaling pattern among various marine navigational lights.

The design of an occulting light is intended to provide clear and recognizable signals to mariners, ensuring that the light can be easily perceived and identified against its darker phases. This pattern helps differentiate it from other light types, reinforcing its role in guiding vessels safely through navigable waters.

In contrast, the other descriptions do not accurately capture the essence of an occulting light. For example, if the period of darkness exceeds the light, it would not be classified as an occulting light, and claiming equal periods does not convey the specific signal benefits that this light configuration provides.