Remote Sensing

The method of detecting and tracking an area’s physical characteristics by analyzing its reflected and emitted radiation from a distance is known as remote sensing (typically from satellite or aircraft).

A satellite imagery that has NDWI calculations in blue to show the extent of flooding.

How Normalized Difference Water Index is Used to Map Flooding

Caitlin Dempsey

The Normalized Difference Water Index (NDWI) is a calculation used in remote sensing to monitor and measure the amount of moisture in vegetation and surface water bodies.

Natural color Landsat scene showing a brown landscape covered by small clouds that dot the landscape.

Landsat: Longest Running Earth Imagery Program

Caitlin Dempsey

With satellites in orbit since 1972, the Landsat program is the longest running Earth observation program.

A lidar image of Washington DC show elevations of the buildings and streets.

Lidar Explained

Caitlin Dempsey

Lidar is a technology developed to map the elevation of features on and below the surface of the Earth.

Earthrise over the Moon: partly-illuminated Earth rising over the lunar horizon. In this photo, the Earth is about 400,000 miles away. Photo: Apollo 11, AS11-44-6552, July 20, 1969.

Overview Effect: Quotes from Astronauts

Caitlin Dempsey

The Overview Effect is a shift in awareness by astronauts seeing Earth from outer space as a “tiny, fragile ball of life.”

Photograph of the Earth captured by astronauts onboard Apollo 17 as they traveled to the moon on Dec. 7, 1972. Image: NASA

Views of Earth from Space

Caitlin Dempsey

Over the decades, Earth has been captured from near and far by astronauts and spacecraft from space.