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• 1 2016-06-13T21:02:58-07:00 NASA's Astronomy Picture of the Day: Between Curation and Randomness 18 plain 2017-11-30T14:33:03-08:00

  By Michael O'Krent

  Since 1995, NASA's Goddard Flight Center has published a daily column featuring an astronomy-related photograph and a brief explanation of its content on its website.  In the spirit of digitization, all previous pictures remain on the website and are accessible through a page entitled "Astronomy Picture of the Day Archive" (link above).  Every day, NASA posts a picture relating to the study of astronomy accompanied by an explanation of what the picture depicts.  APOD claims to be "the largest collection of annotated astronomical images on the internet," thereby combining public interest in fascinating pictures with legitimate and fact-based scientific explanations.
  
  The internet was a much smaller place in 1995.  Accordingly, APOD started small, both in terms of the size of their images and also their complexity.  This is the first APOD image, dated June 16, 1995:
  
  
  Since then, the column has grown, moving from .gif to the more complex and flexible .jpeg format for images, and shifting toward recent discoveries in astronomy.  It has also grown in scope.  A complete outsider, perhaps a visiting alien, could gain a decent idea of the distant extents of the universe that we have observed simply by flipping through this archive.
  
  APOD, however, does not deliberately aim to feature a complete survey of astronomical research.  The archive's comprehensiveness is merely incidental.  Each day features a picture that happens to be interesting; over thousands of days, the full scope of astronomy is covered (or at least, the scope of astronomy that can be captured by images).  The logic of the Astronomy Picture of the Day is just that -- daily.  There is no intent to preserve contemporary astronomy for posterity.  Rather than being future-oriented, the APOD archive is oriented toward the present, toward today.  But because information added to a computer server naturally persists there, and because that information can so easily be organized and made available, thousands of todays have combined to form a substantial record.  A simple project, amplified and exaggerated by the digital tradition of archiving, thus has come to capture dimensions that more rigorously curated archives cannot.
  This archive records both scientific and general history.  This picture is from January 14, 2004, when Britney Spears had just released her song "Toxic" and the Spirit and Opportunity rovers had just landed on Mars.  The photo is a panorama of Mars taken by the Spirit rover.
  
  The archive's astronomical content thus allows it to chronicle the entirety of a planet, to take a true 360-degree view.
  
  And this is today's photo.  Of course, by the time you read these words, they will already be outdated.  Let the record show, then, that this picture is dated June 13, 2016:
  This picture also reminds us that this archive contains pictures, not just photographs.  Although both interplanetary photography and digital illustration technology have substantially improved since 1995, the archive does not simply seek to showcase the advance of technology.  Contrary to what the inclusion of photographs from projects like the Spirit/Opportunity rovers and the ever-improving array of telescopes orbiting earth may suggest, the artist's imagination is as worthy of inclusion as our realistic view of the cosmos.  After all, the goal remains to convey scientific knowledge to the public.  In fact, the comparatively low-tech artist's impression (cf. the Hubble Space Telescope), becomes essential for including the public in scientific discourse because our inability to see the actual object this image depicts.  The picture reflects the more recent shift to participatory astronomy;  amateurs have become indispensable in helping NASA review quantitative data, and the APOD archive even considers submissions from the public.  Today's explanation reads:

  Why does star KIC 8462852 keep wavering? Nobody knows. A star somewhat similar to our Sun, KIC 8462852 was one of many distant stars being monitored by NASA's robotic Kepler satellite to see if it had planets. Citizen scientists voluntarily co-inspecting the data along with computers found this unusual case where a star's brightness dropped at unexpected times by as much as 20 percent for as long as months -- but then recovered. Common reasons for dimming -- such as eclipses by orbiting planets or stellar companions -- don't match the non-repetitive nature of the dimmings. A currently debated theory is dimming by a cloud of comets or the remnants of a shattered planet, but these would not explain data indicating that the star itself has become slightly dimmer over the past 125 years. Nevertheless, featured here is an artist's illustration of a planet breaking up, drawn to depict NGC 2547-ID8, a different system that shows infrared evidence of such a collision. Recent observations of KIC 8462852 did not detect the infrared glow of a closely orbiting dust disk, but gave a hint that the system might have such a disk farther out. Future observations are encouraged and creative origin speculations are sure to continue.

  
  As the pictures I've featured here demonstrate, there is no uniting logic between them, no way to predict what picture tomorrow will bring.  It is possible to sort the archive by the type of object each picture depicts, but that is an ex post facto organizational strategy enabled by attributes of HTML, not the deliberate efforts of the webpage's creators.  Every day features something, and every day features something interesting.  But this literal everyday archive gains its power from the neglect of the formality that has defined previous archives.