Spatial resolution

The ground size of a single pixel. 30 m resolution means each pixel covers a 30 × 30 m square on Earth.

Why it matters

Resolution trades against coverage + revisit. You can have fine pixels OR frequent global coverage, rarely both from one sensor — that’s why NASA flies many satellites.

Where you’ll meet it

• Landsat sees the world in 30 m pixels (15 m panchromatic) — fine enough to pick out individual farm fields, but it only revisits every 16 days.
• MODIS trades detail for coverage with 250 m–1 km pixels, which is why it can image the whole globe daily for fires, clouds, and ocean color.
• Sentinel-2 lands in between at 10–20 m, popular for crop and forest mapping when Landsat’s pixels are a touch too coarse.
• SMAP soil-moisture data comes at a very coarse ~9–36 km because passive microwave signals are weak — a reminder that resolution depends on the physics, not just the optics.

In plain terms

Like camera megapixels, but for the planet — finer pixels see smaller things (a single field) but the file (and the satellite) can’t cover everywhere often.