4/1/12 Big Blue Planet: 50 Years of Photos

Earth has been photographed by NASA for the last 50 years, although the images have certainly changed over time. The first from April 1960, was a grainy black-and-white image taken by the Television InfraRed Observation Satellite, or TIROS-1, which carried with it two small cameras, one for capturing wide views of the Earth as a whole, and the other for more detailed views. In its first three months alone the satellite took 23,000 images, which were used mainly for weather forecasting.

In 2005, NASA created the "Blue Marble: Next Generation" series, which was a year's worth of observations taken by various satellites. The series was named after a famous photo of the Earth taken by the Apollo 17 crew in 1972. Recently, NASA has gone a few steps further by taking new pictures from the perspective of 7,918 miles from Earth. Images were taken during six orbits of the Earth and stitched together to create a single composite image. Earlier this year NASA released two such images of the Earth, one of the Western Hemisphere (below) in January. Then a few weeks later, they released an image of the the Eastern Hemisphere (above).

Another famous picture from space is that of Earth at night. These images were originally created by the Defense Meteorological Satellite Program (DMSP) and the Operational Linescan System (OLS) to view clouds by moonlight. Since most cities tend to be along coastlines, even without the underlying map, the outlines of many continents would still be visible due to this. Interestingly, the U.S. interstate highway system appears as a lattice connecting the brighter dots of city centers when you zoom in.

Sources: NASA, GSFC, NOAA, TechWeb, Information Week