Images of the earth's dayglow emissions at ultraviolet wavelengths, primarily those of atomic oxygen at 130.4 nm, reveal regions of transient intensity decreases to ~ 5% to 20% of surrounding values over areas estimated to be ~ 2,000 km2. The duration of these transient decreases in intensities is ~ several minutes. Approximately 10 out of these events occur each minute in the dayside upper atmosphere. The diurnal variation of the rate of occurence is qualitatively similar to that for radar meteors.