24-Hr Clock Planisphere

A dual-purpose astronomical wall instrument designed by Sahra Industrial Design, uniting true 24-hour diurnal chronometry with a rotatable stereographic planisphere to display a dynamic, perpetual projection of your place in the cosmos.

Apparatus & Design

The Horological Dial

Living Celestial Projection

Features a central freely rotating concentric dial face integrating a stereographic Earth map beneath a transparent overlay star chart[cite: 9].

24-Hour Clock Planisphere featuring stereographic Earth map, constellation overlay, and 24-hour chapter ring[cite: 9]

Full 24-Hour Chapter Ring

Outer dial bezel is indexed continuously from 1 to 24 hours, displaying complete day-and-night cycles without traditional 12-hour ambiguity[cite: 9].

Celestial Alignment

Dual-Layer Architecture

1. Stereographic Polar Earth Base

Complete polar projection mapping continental landmasses, global time zones, and radiating longitude meridians[cite: 9].

2. Transparent Constellation Overlay

Calibrated celestial dome chart depicting stellar asterisms, major celestial coordinates, and Right Ascension graduations[cite: 9].

3. Universal Longitude Interlock

Connecting the discs at the central pivot enables users anywhere on Earth to align local longitude with celestial coordinates[cite: 9].

Diurnal Planetary Tracking

Synchronizes terrestrial daily civil time directly with sidereal star transit, revealing how the cosmos shifts above your hemisphere[cite: 9].

Operation & Observation

Reading & Synchronization

Dial Coordinate Mapping

Dial Element	Reference Scale	Operational Function
Bezel Ring	1–24 Hours[cite: 9]	Diurnal Civil Time[cite: 9]
Top Dial Disc	Right Ascension[cite: 9]	Stellar Dome Overlay[cite: 9]
Base Dial Disc	Stereographic Map[cite: 9]	Global Earth Longitude[cite: 9]
Inner Ring	Time Zone Meridian[cite: 9]	Hemisphere Alignment[cite: 9]

Local Zenith Targeting

1. Identify your local civil time on the 24-hour chapter ring[cite: 9].

2. Align your home city's longitude on the stereographic Earth map with the corresponding Right Ascension value[cite: 9].

3. Read the constellation overlay passing over your geographical meridian to observe what is currently overhead[cite: 9].

Current Zenith = Local Longitude ⊕ Solar Sidereal Offset[cite: 9]