Al-Hilal: Journal of Islamic Astronomy
Vol. 8 No. 1 (2026)

Islamic Prayer Time Calculation in High-Latitude Summer: A Computational Approach Using the Ittibāʿ Aqrab al-Bilād Method in Iceland

Mayrisa Andriyani (Universitas Islam Negeri Sunan Ampel Surabaya)
Siti Nurwilda (Universitas Islam Negeri Sunan Ampel Surabaya)
Sofiyah Sofiyah (Universitas Islam Negeri Sunan Ampel Surabaya)
A’isyah Wulandari (Universitas Islam Negeri Sunan Ampel Surabaya)
Wahyu Ningtiyas Mergianti (Universitas Islam Negeri Sunan Ampel Surabaya)
Nurissaidah Ulinnuha (Universitas Islam Negeri Sunan Ampel Surabaya)



Article Info

Publish Date
26 Apr 2026

Abstract

Determining Islamic prayer times in high-latitude regions is challenging, particularly during summer when continuous twilight prevents the Sun from reaching required depression angles below the horizon. This condition causes conventional solar-angle-based methods to produce undefined (NaN) values for Fajr and Isha. This study proposes a computational approach to address this limitation using Reykjavik, Iceland, as a case study. Astronomical calculations based on solar position parameters are applied to determine Dhuhr, Asr, and Maghrib. At the same time, the ittibā’ aqrab al-bilād method is used to resolve Fajr and Isha by referencing London as the nearest region with normal day–night cycles. The method is implemented in a GUI-based prayer time calculator. Validation shows that the computed times have acceptable deviations, averaging 14–15 minutes compared to established applications, with larger discrepancies for Isha due to persistent twilight. This study offers a practical, computational, and jurisprudential solution to determining prayer times in extreme latitudes.

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Journal Info

Abbrev

al-hilal

Publisher

Subject

Religion Astronomy Earth & Planetary Sciences Physics Social Sciences

Description

Al-Hilal Journal is a scientific journal published in April and October per year by the Islamic Astronomy at the Faculty of Sharia and Law, Universitas Islam Negeri (UIN) Walisongo, Semarang colaboration with Asosisasi Dosen Falak Indonesia (ADFI). Articles published in this journal are the results ...