Earth is made up of complex, interactive systems that are often unpredictable. Air, water, land, and humans themselves combine forces to create a constantly changing world that we are striving to understand. NASA, in partnership with other U.S. and international agencies, has been studying Earth as an integrated system. Viewing Earth from the unique perspective of space provides the opportunity to see Earth as a whole. Scientists around the world have discovered many things about our planet by working together and sharing their findings.
Some facts are well known.
For instance, Earth is the third planet from the Sun, and the fifth largest in the solar system. Earth's diameter is just a few hundred kilometers larger than that of Venus. We experience these motions as the daily routine of sunrise and sunset and the slower change of the seasons. The four seasons are a result of Earth' s axis of rotation being tilted more that 23 degrees. The changing nature of the planet's systems are the mysteries that scientists study today.