Revisit (temporal resolution)

How often a satellite re-images the same place. Daily, every 16 days, every 91 days — depends on orbit + swath.

Why it matters

Fast-moving phenomena (storms, fires, floods) need frequent revisit; slow ones (ice sheets, land cover) tolerate sparse revisit. Match the satellite to the question’s tempo.

Where you’ll meet it

• GPM (Global Precipitation Measurement) constellation produces near-global rain maps roughly every 30 minutes (IMERG) — fast enough to follow storms as they grow.
• MODIS/VIIRS revisit daily, which is why they anchor NASA’s near-real-time fire and flood alerts.
• Landsat returns to the same scene every 16 days; pairing Landsat 8 and 9 effectively halves that to ~8 days for change detection.
• ICESat-2 repeats its ground track on a ~91-day cycle, well matched to slowly evolving targets like ice-sheet elevation and forest height.

In plain terms

Like how often a security camera sweeps back to the same spot — miss the moment and you wait for the next pass.