Here’s a fascinating video by NASA that explains what auroras are and what they look like from space. It’s filled with beautiful photographs and time-lapse sequences captured by astronauts on the International Space Station. Astronaut photographer Don Pettit, who maintains a blog about his experiences, writes that taking pictures of Earth is harder than it looks:
Even with a shutter speed of 1/1000th of a second, eight meters (26 feet) of motion occurs during the exposure. Our 400-millimeter telephoto lens has a resolution of less than three meters on the ground. Simply pointing at a target and squeezing the shutter always yields a less-than-perfect image, and precise manual tracking must be done to capture truly sharp pictures. It usually takes a new space station crewmember a month of on-orbit practice to use the full capability of this telephoto lens.
Another surprisingly difficult aspect of Earth photography is capturing a specific target. If I want to take a picture of Silverton, Oregon, my hometown, I have about 10 to 15 seconds of prime nadir (the point directly below us) viewing time to take the picture. If the image is taken off the nadir, a distorted, squashed projection is obtained. If I float up to the window and see my target, it?s too late to take a picture. If the camera has the wrong lens, the memory card is full, the battery depleted, or the camera is on some non-standard setting enabled by its myriad buttons and knobs, the opportunity will be over by the time the situation is corrected. And some targets like my hometown, sitting in the middle of farmland, are low-contrast and difficult to find. If more than a few seconds are needed to spot the target, again the moment is lost. All of us have missed the chance to take that ?good one.? Fortunately, when in orbit, what goes around comes around, and in a few days there will be another chance.
Earth Photography: It?s Harder Than It Looks (via NASA via MetaFilter)