solstice
Let an agent explain solstices and their astronomical cause, relay dates and variations, describe cultural observances with attribution, and distinguish solstices from equinoxes and from meteorological seasons.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent explain solstices and their astronomical cause, relay dates and variations, describe cultural observances with attribution, and distinguish solstices from equinoxes and from meteorological seasons.
The moment twice a year when the Sun reaches its greatest northern or southern declination, giving the longest day at the June solstice and the shortest at the December solstice in the northern hemisphere and the reverse in the southern, marking astronomical summer and winter, caused by the tilt of the Earth axis; solstices occur on other planets such as Mars, are celebrated in festivals from Stonehenge gatherings to Yule and Dongzhi, and are used as calendar and cultural markers.
What it is for: Not applicable; an astronomical event.
It can be explain the astronomy; relay dates and variations; describe cultural observances; distinguish from equinoxes.
Distinguishing features
Extreme day length
Axial tilt cause
Hemisphere reversal
Cultural festivals
What it looks like
Not a visible object; the Sun at its extreme rising and setting points.
Physical character
axial tilt of Earth: 23.44 degrees
June solstice date: 20-22 June
December solstice date: 20-23 December
How it is recognised
Sun at maximum declination
June and December solstices, summer and winter solstices, Martian solstices
Equinoxes are when day and night are equal; meteorological seasons use calendar months
Related models
is a kind of - in registry terms
is a kind of - in registry terms
is a kind of - in registry terms
is contrasted with - the midpoint events
In practice
Families and kinds
June solstice
December solstice
summer and winter solstices by hemisphere
solstices on other planets such as Mars
solstice observances such as Yule, Dongzhi, Inti Raymi and midsummer
Blue Christmas services near the December solstice
Standards and regulation
No regulation; astronomical almanacs define the times
Failure modes and hazards
Confusing solstice with equinox
Assuming the solstice is the hottest or coldest day
Wrong dates by hemisphere
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Understand What a solstice is.
Science.
Definition
Definition and cause.
Definition
Definition.
- What is a solstice, and how does axial tilt cause it? definition
- Is the question about a solstice, an equinox or a meteorological season? boundary
Dates
Dates and timing.
Dates
Dates.
- When do the solstices occur, and why do the dates vary? measurement
- Which entry fits the specific solstice? action
Observe Observation.
Science.
Sky
Sun path and daylight.
Sky
Sky.
- How do the Sun path, sunrise points and daylight hours change at the solstices by latitude? provenance
- Which entry fits daylight? action
Planets
Solstices on other planets.
Planets
Planets.
- How do solstices work on Mars and other planets? provenance
- Which references are standard? provenance
Culture Culture and festivals.
Attribution.
Festivals
Festivals.
Festivals
Festivals.
- What solstice festivals exist, from midsummer and Yule to Dongzhi and Inti Raymi, with attribution? provenance
- Which entry fits the specific festival? action
Monuments
Ancient alignments.
Monuments
Monuments.
- What monuments align with the solstices, and what do archaeologists say about them? provenance
- Which sources are cited? provenance
Context History and calendars.
Context.
History
History of understanding.
History
History.
- How did ancient astronomers determine the solstices? provenance
- Which entry fits the history of astronomy? action
Calendars
Calendars.
Calendars
Calendars.
- How do calendars and season definitions use the solstices? provenance
- Which entry fits season? action
What the second pass must settle
- Should June and December solstices be separate entries?
- How should almanac sources be linked?
- The registry entry has merged aliases naming observances and planetary events; should they be split off?