Equinox Calendar
Date+ location+ altitude -0.833 deg= sunrise
KnownDate + placeFindSunriseAltitude-0.833 degAzimuthTrue bearingSkyPre-dawnLimitLevel horizon
CalculationTime
Equinox Calendar
A printable season-change planner for Astronomy Engine March and September equinox times, local UTC offsets, prep dates and daylight caveats beside the CalculationTime clockface.
Inputs, result, proof and time.
Use the instrument above, then check the calculation record, assumptions and related tools below.
Printable equinox calendar
Southern observing and season notes
Sydney, Australia - 2027- UTC offset
- +10h
- Prep lead
- 14 days
- Season lens
- South
- Season markers
- Autumn begins; Spring begins
March equinox
Sun, 21 Mar 2027 06:24
UTC estimate: Sun, 21 Mar 2027 20:24NorthSpring begins
SouthAutumn begins
Prep dateSun, 07 Mar 2027
DaylightNearly balanced
The Sun crosses the celestial equator northward; day and night are nearly balanced, but refraction and local horizon shift exact daylight.
September equinox
Fri, 24 Sept 2027 16:01
UTC estimate: Thu, 23 Sept 2027 06:01NorthAutumn begins
SouthSpring begins
Prep dateFri, 10 Sept 2027
DaylightNearly balanced
The Sun crosses the celestial equator southward; this is a seasonal marker, not a promise of exactly twelve daylight hours.
Planner Notes
Use the printed prep date to confirm local sunrise, sunset, school term, garden, teaching or event plans against local sources.
Assumptions
Season instants come from Astronomy Engine Seasons(year). The selected UTC offset is applied only after the UTC event instant is found.
Limits
Use this as a planning worksheet. Verify official event times, local sunrise/sunset and civil schedules before publication or travel.
Method
The worksheet computes equinox instants and converts them into a local planning calendar
The calculator calls Astronomy Engine Seasons(year), selects the March and September equinox UTC instants, converts each instant by the selected offset, subtracts the prep lead time, and keeps the source boundary visible in the printable report.
Astronomy basis
Equinoxes mark the Sun crossing the celestial equator. Equal day and night are approximate because refraction, solar disc size, elevation and horizon shape matter.
Print path
The print button opens browser print. The print stylesheet keeps both equinox rows, local offsets, prep dates, assumptions, notes and source limits.
Limits
This is a planning calendar, not an observatory almanac, school-term source, gardening guarantee, navigation tool or official civil-time record.
Source Notes
Equinox times are engine-backed and should still be checked before publication or travel
CalculationTime uses Astronomy Engine for the UTC season instants and applies the selected UTC offset only after the astronomy calculation. Official almanacs, observatory tables and current ephemerides should still be used for publication-grade event times, daylight-saving changes, local sunrise/sunset and education or travel material.