File:Earth from Orbit- NOAA Satellites Celebrate Earth Day (NESDIS 2022-04-22 2022 04 22 EarthDay TWITTER).webm

English: Throughout history, humans have wondered what Earth looked like from above. The Mesopotamians believed the world was a flat disk floating in an ocean, while Hindu mythology says the Earth is supported by four elephants standing on the back of a giant turtle. Others imagined the world as part of a giant tree, among other ideas. The ancient Greeks first suggested the world was spherical, and Ptolemy is credited as the first to conceive of the world in mathematical terms, publishing his treatise Geographia in AD 150. By the Middle Ages, the belief in a spherical Earth in Europe was relatively widespread. With the birth of the space age, our actual view of the planet from above has changed as well. From blurry images that were stitched together with no frame of reference as to where they were looking, to today’s modern high resolution imagery, our perspective and ideas about what makes the world go round are constantly changing and improving. Since 1970– also the year of the first official Earth Day– NOAA satellites have been monitoring Earth’s weather, environment, oceans, and climate, building upon early pioneering efforts by NASA and others. They provide critical information that feeds forecasts and warns us of severe weather and environmental hazards. NOAA operates two primary types of satellites: geostationary and polar-orbiting. Geostationary satellites orbit 22,236 miles above the equator at speeds equal to Earth’s rotation, meaning they continuously view the same area keeping vigil to identify and track severe weather conditions and environmental hazards. This information is used for short-term (1-2 day) forecasts and for tracking storm systems in real-time. Polar-orbiting satellites circle the globe from the North to the South Pole 14 times a day. They image the entire Earth at least twice daily, from 512 miles above its surface. Earth rotates counterclockwise underneath the path of the satellites, resulting in a different view with each orbit. Global data from polar-orbiting satellites, including atmospheric temperature and moisture profiles, are used in numerical weather models to generate weather forecasts up to seven days out. Polar-orbiting satellites observe the whole world in higher resolution than GOES satellites, allowing for a broader and more detailed view of weather patterns and environmental conditions. NOAA also operates satellites in low-Earth orbit and a deep space satellite at Lagrange point 1, approximately one million miles away from Earth. On board NOAA’s DSCOVR satellite is NASA’s Earth Polychromatic Imaging Camera (EPIC) instrument that watches Earth. These satellites see it all: hurricanes, severe thunderstorms, lightning, fires, dust storms, air quality, fog, volcanic eruptions, vegetation, snow and ice cover, flooding, sea and land surface temperature, ocean health and more. They can even track ship traffic and power outages. Every day, NOAA satellites provide critical information to keep us informed and help us stay safe and to share more answers to the wonder about the Earth that was sparked thousands of years ago.