Which example illustrates passive remote sensing?

Which example illustrates passive remote sensing?

• A. A drone using LiDAR to measure soil depth
• B. A satellite capturing sunlight reflected from Earth’s surface
• C. An active radar imaging system
• D. A weather satellite measuring precipitation

Answer: (B)

The correct choice illustrates the principle of passive remote sensing, where sensors detect natural energy that is reflected or emitted from the Earth's surface rather than providing their own energy source. In this instance, the satellite captures sunlight that is reflected from the Earth's surface. This process relies on ambient light, such as sunlight, to illuminate objects, allowing the sensor to collect data on features such as vegetation, water, or urban areas based on how they reflect different wavelengths of light. The other examples provided involve active sensing methods, where the sensors emit their own energy to gather information. For instance, a drone using LiDAR actively sends out laser pulses to measure distances, enabling it to gauge soil depth based on the time taken for the pulses to return. Similarly, an active radar imaging system emits microwave signals and analyzes their reflections. While a weather satellite does measure precipitation, this activity often involves the use of radar or similar technology that sends out signals, which falls under active sensing rather than passive. Therefore, option B accurately represents passive remote sensing, showcasing the reliance on reflected sunlight to gather data.

The correct choice illustrates the principle of passive remote sensing, where sensors detect natural energy that is reflected or emitted from the Earth's surface rather than providing their own energy source. In this instance, the satellite captures sunlight that is reflected from the Earth's surface. This process relies on ambient light, such as sunlight, to illuminate objects, allowing the sensor to collect data on features such as vegetation, water, or urban areas based on how they reflect different wavelengths of light.

The other examples provided involve active sensing methods, where the sensors emit their own energy to gather information. For instance, a drone using LiDAR actively sends out laser pulses to measure distances, enabling it to gauge soil depth based on the time taken for the pulses to return. Similarly, an active radar imaging system emits microwave signals and analyzes their reflections. While a weather satellite does measure precipitation, this activity often involves the use of radar or similar technology that sends out signals, which falls under active sensing rather than passive. Therefore, option B accurately represents passive remote sensing, showcasing the reliance on reflected sunlight to gather data.