This is how the Earth would look from space were there no clouds to block the view. The image is not just one photograph, but a mosaic of thousands of satellite photos wrapped around a computer-generated sphere. From this vantage point in space, Earth has no countries and no borders; it╒s just a sphere of blues, greens, reds, whites, and browns.
You can zoom in and out and circumnavigate the globe, and then overlay the many boundaries and classifications that humans have created to understand and order their world. A few clicks of your computer mouse will reveal everything from cities and countries to mountains and rivers to lines of latitude and longitude.
The images that you see╤the many tiles of the mosaic╤were collected by an array of satellites known as the Advanced Very High Resolution Radiometers. These satellites originally were designed to observe changes in the Earth's atmosphere, oceans, and vegetation. Space agencies from around the world have since joined regional images into pictures of entire continents, continents into hemispheres, and hemispheres into a single indivisible Earth.
Since the AVHRR satellites only detected green, red, and infrared light, some of the colors on the globe were derived from mathematical formulas and from other images and observations of the planet. For instance, in the oceans, the shades of blue were applied according to depth, with a bit of green added to reflect the multitudes of plankton that color our seas.
⌐ 1996 Planetary Visions Ltd.
Source: AVHRR data courtesy of USGS EROS Data Center
