Twin Blue Marbles

(Click on image for larger view.)  download large Eastern Hemisphere image (3 MB, JPEG, 3718x3718)

 download large Western Hemisphere image (3 MB, JPEG, 3718x3718)

A day’s clouds. The shape and texture of the land. The living ocean. City lights as a beacon of human presence across the globe. This amazingly beautiful view of Earth from space is a fusion of science and art, a showcase for the remote-sensing technology that makes such views possible, and a testament to the passion and creativity of the scientists who devote their careers to understanding how land, ocean, and atmosphere—even life itself—interact to generate Earth’s unique (as far as we know!) life-sustaining environment.

Drawing on data from multiple satellite missions (not all collected at the same time), a team of NASA scientists and graphic artists created layers of global data for everything from the land surface, to polar sea ice, to the light reflected by the chlorophyll in the billions of microscopic plants that grow in the ocean. They wrapped these layers around a globe, set it against a black background, and simulated the hazy edge of the Earth’s atmosphere (the limb) that appears in astronaut photography of the Earth.

The land surface layer is based on photo-like surface reflectance observations (reflected sunlight) measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite in July 2004.

The sea ice layer near the poles comes from Terra MODIS observations of daytime sea ice observed between August 28 and September 6, 2001.

The ocean layer is a composite. In shallow water areas, the layer shows surface reflectances observed by Terra MODIS in July 2004. In the open ocean, the photo-like layer is overlaid with observations of the average ocean chlorophyll content for 2004. NASA’s Aqua MODIS collected the chlorophyll data.

The cloud layer shows a single-day snapshot of clouds observed by Terra MODIS across the planet on July 29, 2001.

City lights on Earth’s night side are visualized from data collected by the Defense Meteorological Satellite Program mission between 1994–1995.

The topography layer is based on radar data collected by the Space Shuttle Endeavour during an 11-day mission in February of 2000. Topography over Antarctica comes from the Radarsat Antarctic Mapping Project, version 2.

Most of the data layers in this visualization are available as monthly composites as part of NASA’s Blue Marble Next Generation image collection. The images in the collection appear in cylindrical projection (rectangular maps), and they are available at 500-meter resolution. The large images provided above are the full-size versions of these globes. In their hope that these images will inspire people to appreciate the beauty of our home planet and to learn about the Earth system, the developers of these images encourage readers to re-use and re-publish the images freely.

NASA images by Reto Stöckli, based on data from NASA and NOAA.

Instrument:
Terra - MODIS