“As of June 4, 2007, the USGS will be releasing selected Landsat 7 image data of the United States through the Web (glovis.usgs.gov or earthexplorer.usgs.gov). These data are of high quality with limited cloud cover.”

Read article at USGS Newsroom
TPE Link- Essentials of Geography: Aerial Photographs and Remote Sensing

Image: Fires burned east of San Diego after a helicopter accidentally clipped power lines. Courtesy NASA (Source)