Satellite images are tools that help us understand the nature of our physical environment and our impact on the environment. The images below are taken from the Landsat satellite as part of a collaborative effort of the US Geological Survey (USGS) and NASA. The images show all of Lancaster County as well as parts of surrounding counties. The Susquehanna River can be seen running from upper left to lower right on the images. The upper Chesapeake Bay is at the bottom of the images.
Landsat collects images using specific wavelengths of light that a sensitive to different features. Combining different wavelengths or bands to highlight specific feature creates the four images below.
Each image is offered at three different resolutions. The images on this page are low resolution best for understanding regional characteristics. By selecting medium resolution you may browse the image at a high enough resolution to see individual farm fields and roads. The high resolution images must be down loaded, unzipped and browsed in Photoshop, Canvas or similar software.
The medium resolution images offer greater resolution for browsing. Individual farm fields are visible at this resolution. concussion.
TM BANDS 3,2,1 (RGB)
This true-color TM band combination creates a natural-looking image. The visible bands (3,2,1) penetrate shallow water and detail water turbidity, currents, bathymetry, and sediment plumes. Smoke plumes are most apparent in this band combination. Healthy vegetation appears in shades of green; soils show as browns and tans.
This band combination is useful for bathymetric and coastal studies. Precise land-water boundaries are more readily delineated using band combinations which include the infrared wavelengths.
TM BANDS 4,3,2 (RGB)
This TM image combines near-infrared Band 4 with visible Bands 3 and 2. Using Band 4 results in more defined water boundaries than in the 3,2,1 image, yet the two visible bands still reveal some water detail and give information about the wetlands and flooded areas.
By displaying the band that senses peak chlorophyll reflectance (Band 4) as red, strong red hues result. The human eye easily discriminates subtle tone variations in this color, and information can be gleaned about the conditions and variety of vegetation. Generally, deep red hues indicate broad leaf and/or healthier vegetation while lighter reds signify grasslands or sparsely vegetated areas. Densely populated urban areas are shown in light blue.
This TM band combination gives results similar to traditional color infrared aerial photography
TM BANDS 4,5,3 (RGB)
This combination of near-infrared Band 4, mid-infrared Band 5, and visible Band 3 offers added definition of land-water boundaries and highlights subtle details not readily apparent in the visible bands alone.
Inland lakes and streams can be located with greater precision when more infrared bands are used. With this band combination, vegetation type and condition show as variations in hue (browns, greens, and oranges), as well as in tone.
The 4,5,3 (RGB) band combination demonstrates moisture differences and is useful for analysis of soil and vegetation conditions. Generally, the wetter the soil, the darker it appears.
TM BANDS 6,4,2 (RGB)
This image demonstrates Landsat TM sensor’s unique ability to measure invisible energy. Collecting data from the infrared regions significantly expands the vision of Landsat TM data users.
This image is a combination of mid-infrared Band 7, near-infrared Band 4, and visible Band 2. The 7,4,2 (RGB) combination retains the benefits of the infrared bands yet presents vegetation in familiar green tones. Mid-infrared Band 7 helps discriminate moisture content in both vegetation and soils.
Urban areas appear in varying shades of magenta. Grasslands appear as light green. The light-green spots inside the city indicate grassy land cover – parks, cemeteries, golf courses. Olive-green to bright-green hues normally indicate forested areas. (In general, coniferous forests tend to be darker green than deciduous.)
Three Mile Island Map