1189: Voyager 1
Voyager 1 is a U.S. space probe launched in 1977 to study the outer reaches of the Solar System and beyond. Popular press has on several occasions announced that it "has left the solar system" at each point when a boundary has been confirmed or a major event has taken place. This underscores the fact that there is no strictly defined and recognizable boundary of the solar system, or at least we haven't found one yet.
The title text lists several such possible boundaries, together with fictive humorous ones:
- The termination shock – the point in the heliosphere where the solar wind slows down to subsonic speed (relative to the star) because of interactions with the local interstellar medium.
- The Heliopause (astronomy) – the theoretical boundary where the Sun's solar wind is stopped by the interstellar medium.
- The heliosphere – a region of space dominated by Earth's Sun, a sort of bubble of charged particles in the space surrounding the Solar System.
- The heliosheath – the region of the heliosphere beyond the termination shock.
- Heliodrome – yet another composition of helios "sun," here together with dromos "course". There is no astronomical object with this name, but it has been used variously in other contexts. One that became famous is a sports hall which was used as a concentration camp in the Bosnian war, see Heliodrom camp.
- Auroral discontinuity - another fictitious astronomic object, for auroral see Aurora (astronomy).
- Heaviside layer – a layer of ionized gas occurring between roughly 90–150 km (56–93 mi) above the ground in the Earth's atmosphere. Popularly recognized for its use as a reference to Heaven in the writings of T. S. Eliot adapted into Andrew Lloyd Webber's musical Cats.
- Trans-Neptunian panic zone – this fictional zone combines the word from two subjects: "Trans–Neptunian" is used in astronomy to describe stuff that occurs beyond the planet Neptune. In Outdoor education the "panic zone" is the opposite of the comfort zone when trying to learn new stuff.
- Magnetogap – part of an ignition system.
- US Census Bureau Solar System statistical boundary – a fictive boundary supposedly defined by the United States Census Bureau, similarly to how it defines census areas for the purpose of processing statistical data about regions in the United States.
- Kuiper gauntlet – this is a play on the Kuiper belt, which is a region of the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun, notable for being full of asteroids; replacing the word "belt" with "gauntlet (glove)" (often spelled 'gantlet') which is a protective glove as well as "gauntlet (punishment)" which is a medieval punishment where one would be forced to run through two lines of men who would hit the punishee.
- Oort void – refers to the Oort cloud, a gigantic "cloud" of materials (mainly composed of ice) which ends around a light-year from The Sun and is deemed the (current) "edge" of the solar system. The "void" may be pun on density of that "cloud" - the number of bodies in it may be huge, but given its size, it's mostly empty.
- Crystal sphere holding the fixed stars – this refers to historical ideas about the universe, particularly the Ptolemaic system, in which the stars were supposed to be fixed on a large crystal sphere around the Earth. It might also be referencing "The Crystal Spheres", a short story by David Brin, in which humanity's first interstellar ship shatters a previously undetected, protective barrier around the solar system. It may also be a reference to the Dungeons and Dragons setting "Spelljammer".
See also Voyager over the “heliocliff,” but Solar System transition mysterious article on Ars Technica.
- Number of times Voyager 1 has left the Solar System
- [22 tally marks.]
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