re Reserve. This large area of deciduous forest, savannah, and wetland is protected as a national park. On the left edge of the scene is Mahajamba Bay. This shallow bay contains Madagascar’s largest mangrove ecosystem, with tidal mudflats along the edges of the mangroves.
Vredefort Impact Structure, South Africa October 14 ,2015
The Vredefort Impact Structure is the oldest and largest known impact crater on Earth. The entire crater is believed to have been about 300 kilometers (186 miles) across and was formed when an asteroid struck the Earth over 2 billion years ago. The asteroid that produced the crater is thought to have been about 5–10 kilometers (3–6 miles) in diameter.
The crater’s outline is now mostly hidden because of weathering and erosion. The only remaining visible feature is the crescent-shaped Vredefort Dome, shown in the center of this Landsat 8 image. The remnant dome is thought to have formed as a direct result of the impact. The southeastern portion of the dome has been covered over time by features that were formed later.
The Vaal River cuts across the dome remnant and its different rock layers. The city of Parys sits along the Vaal River near the dome. The multicolored geometric shapes to the left and right of the dome are related to agricultural land use.
The Landsat 8 optical sensor includes numerous spectral bands that can be used in various combinations, allowing users to accentuate and study specific features on the Earth's surface. This false color image uses a combination of visible and invisible (shortwave infrared) wavelengths to highlight the geological features of the area, in contrast to the surrounding agricultural and urban land use.
Nauru is the world’s smallest island country, with only 21 square kilometers (8 square miles) of land area. Since the early 1900s, the tiny island has been mined for its rich phosphate reserves. By 2000, most of the phosphate deposits had been exhausted, and the strip mining and associated activities had denuded up to 80% of Nauru’s surface. The mining left extensive damage to Nauru’s surface and ecology, but in recent years there have been efforts to rehabilitate the affected areas.
These two Landsat images are false-color composites. The red tones indicate a strong signal from Landsat's near-infrared (NIR) band, which is used by landscape scientists to monitor the presence and condition of vegetation and forested areas. In this type of image, a deep red color indicates actively growing vegetation and forest, while non-vegetated or poorly vegetated areas will have less red tone.
The 1999 Landsat image (left) shows the bright mine scars along with dull, mixed color tones across the landscape, indicating a generally poor condition for the island’s vegetation. The deep red colors throughout the 2015 image (right) suggest an overall increase in vegetation and forest cover.
Landsat imagery can be a valuable tool to help document the history of the mining impacts and track the progress of restoration activities as Nauru works to revitalize their island nation.
Old Name, New Elevation for North America’s Highest Peak September 2, 2015
Secretary of the Interior Sally Jewell recently announced that the highest point in North America, formerly known as Mount McKinley, will be designated by the name Denali in all federal records. Later, U.S. Geological Survey acting Director Suzette Kimball announced that the Denali summit has a new, official elevation of 20,310 feet.
Using the latest methods of satellite-based surveying technology (GPS), a team of mountaineering surveyors under the direction of the U.S. Geological Survey, NOAA’s National Geodetic Survey (NGS), the National Park Service, and the University of Alaska Fairbanks Geophysical Institute re-measured the height of the mountain this summer. The last official survey of the summit had been conducted in 1953.
Scientists from NOAA’s NGS, Dewberry, CompassData, the University of Alaska Fairbanks, and the USGS carefully analyzed the raw data acquired by the survey party to arrive at the final elevation number. The 