Terra's Near-Polar Orbit
Flying at an altitude of 705 km, Terra orbits the Earth once every 98 minutes in a near-polar orbit. The spacecraft descends southward across the equator at 10:30 a.m., when cloud cover is minimal and its view of the surface is least obstructed. As Terra orbits, notice that the Earth is also spinning, so that adjacent orbits are offset somewhat at the equator and there is a small gap between the MODIS instrument's viewing swaths. It will take a little more than 1 day for these gaps to be filled on subsequent overpasses, so that MODIS will provide us snapshots of the entire surface of the Earth within every 2 days.