Solar declination and seasons — identify the event with maximum north declination The Sun's apparent north declination attains its maximum positive value once each year. What is this position/event called in positional astronomy and surveying practice?

Introduction / Context:
Seasonal changes are governed by Earth's axial tilt and its orbit around the Sun. Surveyors and astronomers use standard terms to describe key instants of the Sun's apparent motion on the celestial sphere, which affect day length, solar altitude, and declination used in observations and reductions.

Given Data / Assumptions:

• Declination is measured positive north of the celestial equator and negative south.
• The Sun's declination varies approximately sinusoidally over the year.
• We refer to the northern hemisphere seasonal naming convention.

Concept / Approach:
At the two equinoxes (vernal and autumnal), the Sun's declination is approximately 0°, and day and night are nearly equal. At solstices, the magnitude of declination is maximal: about +23.44° at the June (summer) solstice and about −23.44° at the December (winter) solstice. Therefore, the event when the Sun's north declination is maximum is the summer solstice (around June 21).

Step-by-Step Solution:

Verification / Alternative check:
Solar ephemerides and almanacs list declination values peaking in June for the northern hemisphere, confirming the choice.

Why Other Options Are Wrong:

• Vernal/Autumnal equinox: declination ≈ 0°, not maximum.
• Winter solstice: declination is at its most negative (south) value, not north maximum.

Common Pitfalls:
Mixing hemisphere conventions; forgetting that “north declination maximum” corresponds to midsummer in the northern hemisphere.

Final Answer:
Summer solstice