Watching the Earth From Space
The iconic Apollo 8 image of our Earth rising over a barren moonscape taken in 1968 started the environmental movement by revealing the fragility of our home in the vastness of an implacable universe. Recent images of Earth from across the solar system serve to remind us about the uniqueness of the Pale Blue Dot we call Home!
Apollo 8 image of Earth AS8-14-2383
This image was taken by Astronaut William Anders using a Hasselblad camera with a 3-inch lens.
There are two vantage points in the solar system where we encounter two very different impressions of Earth from space. Across the inner solar system one can still see telescopic details of Earth as a disk of light with oceans, clouds and continents. But beyond Mars and the asteroid belt, Earth’s myriad details quickly collapse with distance into a dot of light seen merely as a bright star.
The NEAR spacecraft took this dramatic image of Earth and our moon from a distance of 250,000 miles as it prepared to embark on its journey to asteroid Eros. The high resolution camera easily sees cloudy details, the continent of Antarctica and a hint of brownish landmass of western Australia. Even hints of large craters on the Moon can be discerned. The NEAR spacecraft camera used 2- inch telescopic lens to see these details. Its angular resolution was about 20 arcseconds per pixel. The human eye by comparison is about 60 asec/pixel. One arcsecond is 1/3600 of a degree in angular measure. On this scale, the full moon is about 0.5 degrees or 1800 asec in diameter.
NEAR image of Earth, with moon’s distance foreshortened
From a distance of 4 million miles, the Galileo spacecraft snapped this image using a telescopic system with a 1-inch lens and you can still —> Read More