By now you’ve probably heard of , the super hi-res composite image of earth. It’s not the single biggest hi-res picture of our planet, but it is a pretty amazing stitch job. Previously, NASA had released Blue Marble pictures of the Western Hemisphere, Eastern Hemisphere, and Australia. (I’ve included all of the pictures below in case you missed them.) Now they’ve released an Arctic image called White Marble that required more stitching than any of the other images. Before we go into that, here’s a little background on how these images are made.
Blue Marble, Western Hemisphere. Photo:
NASA has a satellite called that makes a polar orbit at a distance of 512 miles above the earth. To compose the Western Hemisphere picture of earth shown above, data from eight passes of the satellite were needed. The satellite’s view is restricted; its lens can’t take in the entire earth. If you were to hold a basketball about five-eighths of an inch away from your face and rotate it, you’d get the same perspective that the satellite gets during one pass. After eight passes had been made, NASA scientist Norman Kuring took the resulting images and stitched them together. In the end, he had a picture of earth as seen from 7,918 miles away.
The Blue Marble view of the Arctic took a bit more work.
The satellite makes 14 orbits each day. It passes through the poles on each one of those orbits. While it gets a huge swath of new data at the equator on each pass, it gathers less new data near the poles because it has to pass over the same exact spot at the top each time. To capture the White Marble composite, 15 passes were needed. The 14 daily passes captured most of the top of the earth, but one extra sliver was needed, which the satellite gathered on a 15th pass.
Blue Marble Eastern Hemisphere. Photo:
—Joe Spring