Read equinox and solstice instants from Astronomy Engine Seasons(year), then convert the chosen event into a local planning calendar.
Inputs, result, proof and time.
Use the instrument above, then check the calculation record, assumptions and related tools below.
Working Calendar
Seasons and Solstices Calendar calculator
This calendar route reuses the live calculator from Seasons and Solstices Calculator, then keeps the formula, assumptions and source boundary visible on the calendar URL.
Sun/Moon/Astronomy
Seasons and Solstices Calculator
Live answer2026-03-20 14:45 UTC · autumn beginsAstronomy Engine Seasons(2026) gives March equinox at 2026-03-20 14:45 UTC. Observer-local civil time: 2026-03-21 00:45 (UTC+10). In the Southern Hemisphere this is when autumn begins.
Live result2026-03-20 14:45 UTC · autumn beginsAstronomy Engine Seasons(2026) gives March equinox at 2026-03-20 14:45 UTC. Observer-local civil time: 2026-03-21 00:45 (UTC+10). In the Southern Hemisphere this is when autumn begins.
Formula used
Astronomy.Seasons(year) returns mar_equinox, jun_solstice, sep_equinox and dec_solstice as AstroTime values. The selected AstroTime date is displayed in UTC and shifted by the entered UTC offset for observer-local civil time.
This is the method behind the answer, so the result can be checked rather than simply trusted.
Live math canvas
Your numbers, formula and explanation together
Seasons and Solstices Calculator: 2026-03-20 14:45 UTC · autumn begins. Astronomy Engine Seasons(2026) gives March equinox at 2026-03-20 14:45 UTC. Observer-local civil time: 2026-03-21 00:45 (UTC+10). In the Southern Hemisphere this is when autumn begins.
Formula applied
The exact method behind this answer
CalculationTime keeps the method visible so the number can be checked instead of blindly trusted.
Astronomy.Seasons(year) returns mar_equinox, jun_solstice, sep_equinox and dec_solstice as AstroTime values. The selected AstroTime date is displayed in UTC and shifted by the entered UTC offset for observer-local civil time.
Apply the formulaAstronomy.Seasons(year) returns mar_equinox, jun_solstice, sep_equinox and dec_solstice as AstroTime values. The selected AstroTime date is displayed in UTC and shifted by the entered UTC offset for observer-local civil time.2026-03-20 14:45 UTC · autumn beginsAstronomy Engine Seasons(2026) gives March equinox at 2026-03-20 14:45 UTC. Observer-local civil time: 2026-03-21 00:45 (UTC+10). In the Southern Hemisphere this is when autumn begins.
Your live breakdown
Current inputs in the calculation
These values come from the controls above and update when the calculator changes.
Year
2,026
Season event
March equinox
Hemisphere
Southern Hemisphere
UTC offset
10 hours
Used only to show the observer-local civil date/time beside the exact UTC instant.
Resulting answer
2026-03-20 14:45 UTC · autumn begins
Astronomy Engine Seasons(2026) gives March equinox at 2026-03-20 14:45 UTC. Observer-local civil time: 2026-03-21 00:45 (UTC+10). In the Southern Hemisphere this is when autumn begins.
Answer
2026-03-20 14:45 UTC · autumn begins
Live support
Astronomy Engine Seasons(2026) gives March equinox at 2026-03-20 14:45 UTC. Observer-local civil time: 2026-03-21 00:45 (UTC+10). In the Southern Hemisphere this is when autumn begins.
Assumptions used
What this answer assumes
Astronomy Engine UTC instant with observer-local civil display from the entered UTC offset.
Astronomical event instants are calculated in UTC using Astronomy Engine.
The UTC offset shifts the displayed local civil time; it is not an IANA timezone or daylight-saving database.
Northern and Southern Hemisphere season labels are opposite for solstices and equinoxes.
Master’s Tip
How to use the result well
Master’s Tip: write whether you mean meteorological seasons or astronomical seasons. This page uses the equinox/solstice convention.
Printable record
What belongs in the saved calculation
Save the inputs, result, formula, assumptions, page URL and date together so the calculation can be reviewed later.
Year
2,026
Season event
March equinox
Hemisphere
Southern Hemisphere
UTC offset
10 hours
Used only to show the observer-local civil date/time beside the exact UTC instant.
Visual grid
This number is one point on a larger pattern
Seasons and Solstices is not just a final answer. It is a step on a line: before and after, input and output, assumption and result.
Micro-timehours, minutes, shiftsHuman scaledays, weeks, projectsMacro-timemonths, years, calendars
InputFormulaResult
2026-03-20 14:45 UTC · autumn begins
CalculationTime keeps the path visible: the input, the method and the final number belong together.
CalculationTime
Seasons and Solstices Calculation Report
Report date:
2026-03-20 14:45 UTC · autumn beginsAstronomy Engine Seasons(2026) gives March equinox at 2026-03-20 14:45 UTC. Observer-local civil time: 2026-03-21 00:45 (UTC+10). In the Southern Hemisphere this is when autumn begins.
Inputs
Year
2,026
Season event
March equinox
Hemisphere
Southern Hemisphere
UTC offset
10 hours
Method
Astronomy.Seasons(year) returns mar_equinox, jun_solstice, sep_equinox and dec_solstice as AstroTime values. The selected AstroTime date is displayed in UTC and shifted by the entered UTC offset for observer-local civil time.
For 2026 in the Southern Hemisphere, the June solstice is calculated from Astronomy.Seasons(2026) and marks the start of winter by the astronomical-season convention.
Assumptions
Astronomical event instants are calculated in UTC using Astronomy Engine.
The UTC offset shifts the displayed local civil time; it is not an IANA timezone or daylight-saving database.
Northern and Southern Hemisphere season labels are opposite for solstices and equinoxes.
Notes
Use this space on the printed report for client, supplier, classroom, job-location, measurement, quote or approval notes.
Method
The calendar uses Astronomy Engine season instants, not polynomial shortcut copy
The route calls Astronomy Engine Seasons(year), chooses the selected equinox or solstice, applies the entered fixed UTC offset for display, and labels the season by hemisphere.
Formula
Astronomy.Seasons(year) returns mar_equinox, jun_solstice, sep_equinox and dec_solstice as AstroTime values. The selected AstroTime date is displayed in UTC and shifted by the entered UTC offset for observer-local civil time.
Assumptions
Astronomical event instants are calculated in UTC using Astronomy Engine. The UTC offset shifts the displayed local civil time; it is not an IANA timezone or daylight-saving database. Northern and Southern Hemisphere season labels are opposite for solstices and equinoxes.
Trust boundary
Season instants are astronomy events, while local daylight, weather, school terms and cultural season labels can differ. Use official almanacs for publication-grade event tables.
Source Notes
Seasons and Solstices Calendar keeps the source limits visible
CalculationTime calculates selected equinox and solstice instants with Astronomy Engine and labels the corresponding season by hemisphere.