The Spectrum Satellites See

Every Earth-observing satellite is a set of decisions about which slivers of the electromagnetic spectrum are worth measuring. Here they all are on one axis, drawn to scale.

The axis is logarithmic, so each step to the right is ten times the wavelength. Drag across it to zoom into a range, double-click to pull back out, shift-drag to slide sideways. Sentinel-2's thirteen bands live inside a stretch narrower than the word "Microwave".

How to read this

Ribbon: the named regions, with the visible slice painted in its own colours and the radar letter bands below.
Atmosphere: how much of a clear sky a wavelength gets through. Every notch in that curve is a gas eating the signal, and the label inside it names the culprit: water vapour, carbon dioxide, ozone, oxygen. Bands go in the windows between them, never in the walls.
Surfaces: below 2.5 µm, the fraction of sunlight each material sends back. Above 3 µm, its emissivity: how efficiently it radiates its own heat. A good absorber is a good emitter, so the two are complements, and together they describe the surface across the whole chart.
Rows: each mission's bands at their true position and width. Radar bands are hairlines because a SAR transmits one nearly pure tone.
Hover a band for its job. The bar underneath tracks your cursor wavelength and what it can see through.
Click a sensor name or a ribbon segment to zoom straight to its range. The strip above the chart shows which slice of the whole spectrum you are looking at: drag it to move around, and clear the zoom with the × or the escape key.

Jump to

Layers

Sensors

Surface response

Spectral index

Band positions and widths come from published instrument specifications (Sentinel-2A MSI, Landsat 8/9 OLI-2 and TIRS-2, GOES-R ABI and GLM, JPSS VIIRS, Sentinel-1 C-SAR, NISAR L and S band). Radar wavelengths are computed from centre frequency and chirp bandwidth. The reflectance, emissivity, atmospheric transmission and penetration curves are stylised: they carry the shapes that drive band design, not laboratory measurements.

drag across the chart to zoom into a range

Cursor wavelength

Clear-sky transmission

Reflectance here

Bands at this wavelength

What it sees through

This wave, actual size