Polar Regions

Polar Regions

Above the Arctic Circle (or below the Antarctic Circle), the sun may never rise or set for days or weeks. Al-Falak provides configurable strategies for these situations.

PolarCircleRule options

Rule	Behavior
NEAREST_LATITUDE	Compute at nearest latitude where sun rises/sets (default)
NEAREST_DAY	Use schedule from nearest date with normal sunrise/sunset
MAKKAH	Use Makkah’s schedule for the same date
NONE	Raise AstronomicalError (no fallback)

Using a polar rule

from alfalak import PrayerTimes, CalculationParameters, PolarCircleRule

params = CalculationParameters(
    polar_circle_rule=PolarCircleRule.NEAREST_LATITUDE,
)
prayer_times = PrayerTimes(
    (78.2232, 15.6267),  # Longyearbyen, Svalbard
    datetime.now(),
    calculation_parameters=params,
)

NEAREST_LATITUDE (default)

Aqrab al-Bilad: finds the nearest latitude (same longitude, same date) where the sun still rises and sets. This is the default behavior.

NEAREST_DAY

Aqrab al-Ayyam: finds the nearest date (same location) with a normal sunrise/sunset schedule. Returned datetimes carry that date.

MAKKAH

Uses Makkah’s coordinates (21.4225°N, 39.8262°E) for the same date. Useful for consistency with the Haram schedule.

NONE

No fallback. Raises AstronomicalError when the sun never rises or sets:

from alfalak import PrayerTimes, CalculationParameters, PolarCircleRule, AstronomicalError

params = CalculationParameters(polar_circle_rule=PolarCircleRule.NONE)
try:
    PrayerTimes((78.2232, 15.6267), datetime.now(), calculation_parameters=params)
except AstronomicalError as e:
    print(f"Polar day/night: {e}")

Important notes

• Estimates are approximations: near the polar boundary, adjacent markers can invert by minutes
• The NEAREST_LATITUDE strategy backs off 0.5° from the exact boundary to ensure a usable day/night split
• All strategies preserve the original date in the returned datetimes (except NEAREST_DAY which uses the nearest valid date)