Images
Images of auroras are significantly more common today due to the rise of use of digital cameras that have high enough sensitivities. Film and digital exposure to auroral displays is fraught with difficulties, particularly if faithfulness of reproduction is an objective. Due to the different spectral energy present, and changing dynamically throughout the exposure, the results are somewhat unpredictable. Different layers of the film emulsion respond differently to lower light levels, and choice of film can be very important. Longer exposures aggregate the rapidly changing energy and often blanket the dynamic attribute of a display. Higher sensitivity creates issues with graininess.
David Malin pioneered multiple exposure using multiple filters for astronomical photography, recombining the images in the laboratory to recreate the visual display more accurately. For scientific research, proxies are often used, such as ultra-violet, and re-coloured to simulate the appearance to humans. Predictive techniques are also used, to indicate the extent of the display, a highly useful tool for aurora hunters. Terrestrial features often find their way into aurora images, making them more accessible and more likely to be published by the major websites. It is possible to take excellent images with standard film (using ISO ratings between 100 and 400) and a single-lens reflex camera with full aperture, a fast lens (f1.4 50 mm, for example), and exposures between 10 and 30 seconds, depending on the aurora's display strength.
Early work on the imaging of the auroras was done in 1949 by the University of Saskatchewan using the SCR-270 radar.
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Aurora borealis from the International Space Station
Aurora during a geomagnetic storm that was most likely caused by a coronal mass ejection from the Sun on 24 May 2010. Taken from the ISS
Diffuse aurora observed by DE-1 satellite from low Earth orbit
Read more about this topic: Aurora (astronomy)
Famous quotes containing the word images:
“Imagination could hardly do without metaphor, for imagination is, literally, the moving around in one’s mind of images, and such images tend commonly to be metaphoric. Creative minds, as we know, are rich in images and metaphors, and this is true in science and art alike. The difference between scientist and artist has little to do with the ways of the creative imagination; everything to do with the manner of demonstration and verification of what has been seen or imagined.”
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