Anticenter shell
supershell located outside of the galaxy
The anticenter shell or anticenter superbubble is a region near the anticenter of the Milky Way Galaxy that emits 21 cm radiation. It is located at 06h 27m +15°, or l = 197°, b = +2° in galactic coordinates, near the border of the constellations Gemini and Orion. It is a supershell (a very large superbubble) within our galaxy that is spherical in shape and features jets of gas.
Discovered in 1970, this galactic object has subsequently been variously classified by researchers as a spiral arm of the Milky Way in 1972, a nearby tidally-stripped dwarf galaxy in 1975, and a high-velocity cloud in 1979.
The name Snickers for the anticenter shell arose from the description in 1975 by Christian Simonson, a University of Maryland astronomer who believed it to be a small "peanut" of a galaxy just outside the Milky Way.
Simonson's colleagues coined the name Snickers (in reference to the American chocolate bars Milky Way and Snickers) due to its proximity to the Milky Way. Less popularly, the anticenter superbubble is also referred to as 0627-15 from its equatorial coordinates.
The anticenter shell is approximately 55,000 light years (17 kpc) from the Sun. Its dimensions are difficult to determine by radio observation due to its location near the Zone of Avoidance, the regions of the sky obscured by interstellar dust along the galactic equator.
Begin with the source’s own compact description: “Anticenter shell” is supershell located outside of the galaxy. The dossier treats that line as a proposition to test through Anticenter, shell and supershell, not as a finished interpretation.
Why this record matters
The phrase “supershell located outside of the galaxy” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Sep 13, 2026. The linked authority identifier is Q3977681. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1970, 1972, 1975 and 1979.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Anticenter shell”, its source revision and the description used here.
- Expand the search: follow Anticenter shell primary sources, Anticenter shell archive and Anticenter research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Anticenter shell”?
- What terminology or title could unlock a more precise catalogue search?
- Which cited source is closest to the event, object or claim?
Search terms from this dossier
This entry incorporates text from “Anticenter shell” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.