Astronomy — Equinox Months The two annual equinoxes (when day and night are approximately equal worldwide) occur in which pair of months?

Introduction / Context:
Equinoxes mark the moments when the Sun crosses the celestial equator and the Earth experiences roughly equal day and night lengths. This is a staple concept for calendars, seasons, and celestial navigation. Knowing the typical months helps in correlating seasonal changes across hemispheres.

Given Data / Assumptions:

• Equinoxes occur twice each year.
• Vernal (March) equinox begins northern spring; autumnal (September) equinox begins northern autumn.
• Dates shift slightly year to year (around 20–23 of the month) but the months are consistent.

Concept / Approach:
Because of Earth's orbit and axial tilt, the Sun's apparent path intersects the celestial equator around March and September annually. These are the only months that fit the global pattern of day–night equality, with solstices occurring in June and December instead.

Step-by-Step Solution:

Verification / Alternative check:
Any astronomical almanac or school atlas calendar highlights equinoxes in March and September.

Why Other Options Are Wrong:

• January/June and July/December include a solstice month rather than equinox pairs.
• September/December pairs an equinox with a solstice.

Common Pitfalls:
Confusing equinoxes with solstices, which mark maximum/minimum solar declination.

Final Answer:
March and September