Nighttime (ascending) Landsat scenes can be searched for, then either downloaded or requested for processing through EarthExplorer.
To search for nighttime scenes, you can use either the daytime (descending) path/row, nighttime (ascending) path/row, or the coordinates of your area of interest. If none of this information is known, you can select your area of interest on the map.
Note: Nighttime path/row numbers are not the same as daytime path/row numbers.
To search for nighttime (ascending) scenes, follow these steps:
If you know the daytime path/row or coordinates, and want to know the nighttime path/row, access the WRS-2 Path/Row to Latitude/Longitude Converter.
Note: If the coordinates are known, you can skip step 1.
Note: Cloud cover values for night scenes will always be zero for Landsat 7 images. This FAQ explains why.