essential
likely
maybe
probably not
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Active vs passive remote sensing?
Plain English (default view) — short, conversational, lightly seasoned with science
🔬 Scientific / formula (revealed on click) — markdown + $$…$$ ok
- 👂 **Passive** — sensor only *receives* natural energy - Source: solar reflection or target's thermal emission - Examples: Landsat, MODIS, SPOT, IKONOS - Limit: needs the Sun (or warm objects for thermal) - 📢 **Active** — sensor emits its own pulse and measures the return - Works day or night, often through clouds - Examples: **Radar**, **LiDAR**, scatterometers Mnemonic: passive *listens*; active *shouts and listens*.
💡 Mnemonic / memory aid (shown on hover)
Passive = listens. Active = shouts and listens. Active works at night (radar/LiDAR don't need the sun).
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