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==Explanation==
 
==Explanation==
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''{{w|Voyager 1}}'' is a [[:Category:Space probes|space probe]] launched by the United States in 1977. Originally designed to study the outer planets of the {{w|Solar System}}, it is now several decades into an extended mission beyond Neptune (see [[#Trivia]]). The Voyager probe has made history for passing many milestones of our solar system.
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{{incomplete|Created by a MISSING PHYSICAL PHENOMENON LOST DUE TO HIGH COMPRESSION. More on the title text - dark matter and dynamic range issues need to be explained in more detail. Do NOT delete this tag too soon.}}
  
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When images are compressed by a {{w|lossy compression}} format (e.g. {{w|JPEG}}), visual artifacts are created. Randall here is suggesting that the probe has passed the artifacts as if the artifacts were an actual feature of the solar system rather than a consequence of our technology.  The banding lines he has drawn are commonly seen in old images with low bit depth.
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''{{w|Voyager 1}}'' is a [[:Category:Space probes|space probe]] launched by the United States in 1977. Originally designed to study the outer planets of the {{w|Solar System}}, it is now several decades into an extended mission beyond Neptune. The Voyager probe has made history for passing many milestones of our solar system.
  
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The 'solar system' in the snapshot appears to be a 4-bit greyscale-plane at a more pixelated level than the image given. It contains 16 'banded' levels from the brightest (closest zones, within this image, to the Sun) to darkest (the furthest illustrated expanses, including interstellar space), with irregular or non-trivial transitional edges but no obvious or dominant dithering/speckling or 'noise'. The Voyager image (and track) is overlaid in a white 'line drawing' format.
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When images are compressed by a {{w|lossy compression}} format (e.g. {{w|JPEG}}), visual artifacts are created. Randall here is suggesting that the probe has passed the artifacts as if the artifacts were an actual feature of the solar system rather than a consequence of our technology.  The banding lines he has drawn are commonly seen in old images with low bit depth built by software that doesn't implement a technique to remove them called dithering. However, the slightly discolored regions often created by compression could also be a metaphor for the region of space that that solar radiation prevents from being a complete vacuum: because there is some gas in these areas, they may reflect light, causing banding lines when their density is high enough. Voyager 1 has passed through numerous such boundaries, as mentioned previously in [[1189: Voyager 1]].
  
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Each apparent pixel in this low-res rendering is approximately 1 AU², where 1 AU ({{w|astronomical unit}}) is the distance from the Sun to the earth. The Sun is off the left side of the image by about 30 pixels, meaning that of all the planets in the solar system, only Neptune would have an orbit that is within the image at all (at the left edge). The {{w|heliosphere}} is 120 AU from the sun, in the direction that Voyager 1 is travelling: Voyager crossed that milestone in August 2012. At time of publication Voyager was just over 150 AU from the Sun, as shown in the image.
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Compression artifacts are often caused by large changes in coloration over a short distance, and Randall could feel that the drastic change in coloration from bright sun to dark vacuum could be creating a compression artifact around the Sun, somewhat like the Sun looking blurry due to low video quality. However, there is no definite region where solar radiation stops, only a boundary where it fades to a level lower than that of radiation from other sources. Some compression methods result in compression artifacts that behave in the same way, fading as the distance from the color boundary increases but never completely disappearing.
  
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Continuing on its course at 38,000 mph, or 3.6 AU/year, Voyager will reach the outer edge of the {{w|Oort cloud}}, the edge of our solar system, in about 300 years.
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The 'solar system' in the snapshot appears to be a 4-bit greyscale-plane at a more pixelated level than the image given. It can be picked out as being in 16 'banded' levels from the brightest (closest zones, within this image, to the Sun) to darkest (the furthest illustrated expanses, heading into interstellar space), with irregular or non-trivial transitional edges but no obvious or dominant dithering/speckling or 'noise'. The Voyager image (and track) is overlaid at finer resolution in the white 'line drawing' format.
  
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The title text refers to 'our spacetime {{w|codec}}', suggesting a representation of reality itself as a series of ones and zeros. If empty space is the darkest possible thing that can be represented--which may be the case when only 16 levels are available (see above)--then it is possible that {{w|dark matter}} is ''so'' dark that it cannot be represented: it would require a negative number, which is not available. This is the {{w|dynamic range}} issue mentioned.
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The 'apparent pixels' seem to be at a resolution close to the order of 1AU². A rough count of the pixelation boundaries from the craft to the leftmost edge, plus an additional allowance for the likely radius of the 'sun' (or, rather, its solar wind density, or similarly represented measure) still beyond the edge, is surprisingly close to to the ~150 AU current distance of Voyager 1.
  
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Artefacts are evident in [[1683: Digital Data]], and mentioned in the title text of [[331: Photoshops]].
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For perspective, the Earth is then within/adjacent to the single lower-resolution 'pixel' that holds the Sun, and as of the comic's date of publication, over on its far side. But the Sun itself is not even visible, as the bright ball of pixels representing its environs is centered off the left side of the comic. It would be a dot so far beyond the left boundary of the image that Neptune, at around 30 'pixels' distance, may only ''just'' be placed within the leftmost extreme of this view at its own rightmost point in its orbit. The overlaid Voyager 'sketch' (in its more native resolution/bit-depth and antialiasing) stretches out over maybe a dozen such low-res pixels/AUs; this suggests that the viewpoint of the observer is close to the Voyager craft, making the craft appear large by comparison.
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In the title text the mystery of the undetectable {{w|Dark Matter}}, which current mainstream physics supposes makes up most of the mass in the universe, is explained since this dark matter is rendered completely undetectable by our spacetime codec's {{w|dynamic range}} issues (thus brushing against the theme of a simulated universe).
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Artifacts are evident in [[1683: Digital Data]], and mentioned in the title text of [[331: Photoshops]].
  
 
==Transcript==
 
==Transcript==
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:[Caption below the panel]: Milestone: ''Voyager'' has passed through the streaming video compression artifacts that mark the edge of the solar system
 
:[Caption below the panel]: Milestone: ''Voyager'' has passed through the streaming video compression artifacts that mark the edge of the solar system
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==Trivia==
 
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* At the time of the fly-by of {{w|Neptune}}, in 1989, it was the outermost of the nine officially recognised planets.
 
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* The more highly eliptical orbit of {{w|Pluto}}, which was also unfavourably positioned for any Voyager mission encounter, meant that it would be another ten years before it was the actual outermost planet, well behind the respective Voyager crafts' progress away from the Sun.
 
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* Pluto was then 'demoted' from being a full planet in 2005, meaning that Neptune officially became the outermost of the (eight) planets, well in advance of the next orbital 'switch' (roughly in the 2220s to 2240s) when Pluto's path would bring it closer to the Sun once more.
 
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* However Pluto (and partner bodies/'moons') finally experienced its own {{w|New Horizons|fly-by mission}} in 2015, which ''may'' perhaps have softened some of the psychological blow from the various snubs it had experienced over the prior decades.
 
  
 
{{comic discussion}}
 
{{comic discussion}}
  
 
[[Category:Space probes]]
 
[[Category:Space probes]]

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