Definition

1. Noun:
   • The time for the earth to make one revolution around the sun, measured between two vernal equinoxes: A "tropical year" is the precise period it takes for the Earth to complete one full orbit around the Sun, with the measurement defined by the cycle of the seasons, specifically from one vernal equinox to the next.

Usage

• The term "tropical year" is used in astronomy, calendrical science, and precise timekeeping to define the seasonal cycle. It is the basis for the solar calendar (like the Gregorian calendar). It is a technical term.

Examples

• Noun:
  • The length of a tropical year is approximately 365 days, 5 hours, 48 minutes, and 45 seconds.
  • Our modern calendar is designed to stay in sync with the tropical year.
  • Astronomers carefully measure the tropical year to understand long-term changes in Earth's orbit.

Advanced Usage

• "Mean tropical year": The average length of the tropical year over many cycles, which is the standard value used in calculations (about 365.24219 days).
  • The mean tropical year is the fundamental unit for constructing solar calendars.

Variants and Related Words

• Solar year: Often used synonymously with "tropical year," though it can sometimes refer to other solar-based measurements.
• Equinoctial year: Another, less common, term for "tropical year," emphasizing its definition from equinox to equinox.
• Anomalistic year: A different astronomical year measured from perihelion to perihelion (Earth's closest approach to the Sun), which is slightly longer than a tropical year.

Synonyms

• Solar year (in its precise, seasonal sense).

Notes

• The tropical year is not exactly the same as the sidereal year, which is measured relative to the fixed stars. The tropical year is about 20 minutes shorter due to the precession of the equinoxes.
• It is crucial for keeping calendars aligned with the seasons; the drift of seasons in a calendar is due to a mismatch with the tropical year length.

Noun

1. the time for the earth to make one revolution around the sun, measured between two vernal equinoxes