 Return of the Blue Marble, presented by Science at NASA. As Mark Twain once said, distance lends enchantment to the view. This definitely holds true for the Deep Space Climate Observatory, or Discover, a new space weather mission from NOAA that also carries NASA instruments to keep an eye on Earth. Launched in February 2015, Discover is now a million miles from Earth where we can look back and see half our planet all at once. The view-prompted President Obama to tweet just got this new Blue Marble photo from at NASA, a beautiful reminder that we need to protect the only planet we have. The first Blue Marble photos taken by Apollo astronauts nearly 50 years ago sparked a new awareness of Earth as a fragile sphere of dazzling beauty floating alone in a dangerous void, worthy of careful stewardship. They energized grassroots green movements and inspired young scientists who would go on to investigate climate change, forecast weather, and much more. None of the modern Earth-observing satellites, however, can see the entire sunlit side of Earth all at once. They're too close. Satellites in low Earth orbit collect high-resolution images swath by swath on consecutive overpasses. To see the whole Earth, the pieces have to be stitched together from pieces obtained at different instants all at the same local time. Geostationary satellites can see the entire planet and let us watch the Earth evolve by using multiple satellites to build a full picture. These satellite systems typically only get observations during the day. Adam Sabo, Discover project scientist at NASA's Goddard Space Flight Center, says, the Discover mission provides a new and complementary view of Earth. Discover floats at the first Sun-Earth Lagrange point, L1, a sort of gravitational parking spot for spacecraft. Here the gravitational pull of the Sun and Earth cancel out, providing a quasi-stable orbit. It's the perfect spot for Discover's camera to capture full sunlit disc images of Earth in one picture all at the same instant from sunrise to sunset. By capturing full disc images in 10 wavelengths approximately every 1.8 hours, Discover can answer questions about daily variations on the Earth. For example, it can help researchers understand the ozone layer and the variability of cloud cover from sunrise to sunset. Discover will also help scientists track aerosols. Sabo tells us it can see massive dust clouds moving from the Sahara desert to the southern U.S. and Central America. And it can see smoke from large forest fires in remote northern Canada where nobody keeps an eye out. L1 Discover will also be in perfect position to look out for a very real external threat. The ionized pieces of the Sun, it hurls our way, which are known as coronal mass ejections. Discover will be the nation's first operational space weather satellite in deep space. A partnership between NASA, NOAA, and the U.S. Air Force, this mission's primary objective is, in fact, to help NOAA provide timely space weather alerts and forecasts. The observatory also offers a rare view of the Moon. Because the Moon is tidally locked to Earth, only one side is visible from our planet. The unseen far side was shrouded in mystery until 1959 when the Soviet Luna 3 spacecraft swung around the Moon and photographed it from behind. This feat is repeated by the current high-resolution U.S. Lunar Reconnaissance Orbiter Camera, or LROC. Discover will observe the far side about twice a year as the observatory periodically crosses the orbital plane of the Moon. Discover's first images of the Moon transiting Earth in July were a social media sensation. Since Discover began regular observations, NASA is posting daily color images of Earth to a dedicated public website. These images, showing different views of the planet as it rotates through the day, will be available 12 to 36 hours after they are acquired. These are the first true color Earth images where the colors are adjusted to closely match what the average human eye would see. Find Discover's daily images at epic.gsfc.nasa.gov. Stay tuned for more about these enchanting photos of the Blue Marble at science.nasa.gov.