Solar Noon, Zawal and Dhuhr: Why Dhuhr Is Not 12:00 PM

Solar noon, zawal and the Dhuhr column

In astronomical terms, solar noon (meridian transit or istiwa) is the instant when the sun reaches its highest point in the sky and crosses the local north–south meridian. In timetable terminology:

• Before solar noon: The sun is still rising toward the meridian. Some schedules mark a short precautionary buffer (often 5 to 10 minutes before meridian transit) as zawal or istiwa, when optional prayers are paused.
• Dhuhr (Zuhr) start: Once the sun has passed the meridian and begins to descend, the Dhuhr window opens.
• Precautionary minutes in presets: Standard geometric presets in Adhan (such as Karachi, ISNA and Muslim World League) place Dhuhr just after solar transit, whereas the Moonsighting Committee Worldwide preset (SalahTable's UK default) adds 5 minutes after solar noon as a built-in precaution.

Why solar noon is rarely 12:00 PM

Two astronomical and civil effects move solar noon away from 12:00 PM on your watch:

1. Longitude within your time zone: Each 15° of longitude corresponds to 60 minutes of solar time (4 minutes per degree). If your city lies west of its time zone's standard meridian—such as Karachi (67.0° E vs the 75° E meridian of UTC+5) or Singapore (103.8° E vs the 120° E meridian of UTC+8)—the sun reaches your meridian 30 to 65 minutes after 12:00 PM.
2. The Equation of Time: Because Earth's orbit is elliptical and its axis is tilted 23.4°, solar noon drifts back and forth by about −14 to +16 minutes across the calendar year even at a fixed longitude. Daylight saving time adds a further 60-minute clock jump in summer (see daylight saving and prayer times).