Spectral band

A specific range of wavelengths a sensor measures. Each band captures how much light of that color (visible or invisible) a surface reflects or emits.

Why it matters

Different materials have distinctive spectral signatures — healthy vegetation reflects near-infrared strongly, water absorbs it. Combining bands reveals what’s on the ground.

Where you’ll meet it

• MODIS carries 36 bands from visible to thermal infrared, feeding products as different as the NDVI vegetation index, sea-surface temperature, and cloud detection.
• Landsat 8/9 OLI/TIRS split light into 11 bands — including a “coastal aerosol” band for shallow water and two thermal bands for surface temperature.
• Hyperspectral sensors like EMIT (on the ISS) record hundreds of narrow contiguous bands, fine enough to fingerprint specific minerals in dust source regions.
• Sentinel-2 MSI offers dedicated red-edge bands that sharpen the line between healthy and stressed crops — a band choice driven purely by vegetation’s spectral signature.

In plain terms

Like separating white light through a prism — each band is one slice of the rainbow, including slices our eyes can’t see (infrared, ultraviolet).