Feb. 24, 2012 -- We at Discovery News are loving the new photos of Earth coming in from VIIRS, the biggest and most important instrument of the five aboard NASA's Earth-observing satellite - Suomi NPP. These composite images are put together using a number of swaths of the Earth's surface taken with the Visible/Infrared Imager Radiometer Suite (VIIRS) over the course of a day as the Suomi NPP satellite orbits the planet from pole to pole. Here we see the western hemisphere from swaths taken on Jan. 4, 2012.
The Suomi NPP satellite flew over the eastern hemisphere six times during an eight hour time period on Jan 23, 2012. NASA scientist Norman Kuring took those six sets of data and combined them into this image shown here.
Here NASA scientist Norman Kuring has done the same with the VIIRS data sets taken on Feb. 8, 2012.
The newly launched Suomi National Polar-orbiting Partnership (S-NPP) satellite, which was blasted into space on Oct. 28, 2011, circled the Earth 15 times to capture the visual data used for the stunning picture.
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Hot and Cold
Here we see the results of the Clouds and the Earth's Radiant Energy System (CERES) instrument at work on the Suomi NPP satellite.
"In the longwave image, heat energy radiated from Earth (in watts per square meter) is shown in shades of yellow, red, blue and white. The brightest-yellow areas are the hottest and are emitting the most energy out to space, while the dark blue areas and the bright white clouds are much colder, emitting the least energy. Increasing temperature, decreasing water vapor, and decreasing clouds will all tend to increase the ability of Earth to shed heat out to space," the NASA CERES team explained.
Keeping Up with the Sun
From its vantage 824 kilometers (512 miles) above Earth, the Visible Infrared Imager Radiometer Suite (VIIRS) on the NPOESS Preparatory Project (NPP) satellite gets a complete view of our planet every day. This image from Nov. 24, 2011, was the first complete global image from VIIRS.
Rising from the south and setting in the north on the daylight side of Earth, VIIRS images the surface in long wedges measuring 3,000 kilometers (1,900 miles) across. The swaths from each successive orbit overlap one another, so that at the end of the day, the sensor has a complete view of the globe. The Arctic is missing because it is too dark to view in visible light during the winter.
The NPP satellite was placed in a Sun-synchronous orbit, a unique path that takes the satellite over the equator at the same local (ground) time in every orbit. So, when NPP flies over Kenya, it is about 1:30 p.m. on the ground. When NPP reaches Gabon—about 3,000 kilometers to the west—on the next orbit, it is close to 1:30 p.m. on the ground. This orbit allows the satellite to maintain the same angle between the Earth and the Sun so that all images have similar lighting.
The consistent lighting is evident in the daily global image. Stripes of sunlight (sunglint) reflect off the ocean in the same place on the left side of every swath. The consistent angle is important because it allows scientists to compare images from year to year without worrying about extreme changes in shadows and lighting.
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Electro Magnetic Interference testing of the Suomi NPP satellite at the Ball Aerospace facility.
Behind the Scenes
By stitching six swaths together, NASA scientist Norman Kuring takes the Suomi NPP satellite perspective from its polar orbit around Earth at an altitude of 512 miles (about 824 kilometers), and changes it to a 'Blue Marble' view as though it were seen from 7,918 miles (about 12,743 kilometers).
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