The Self-Reliance Library
Tell Time by the Sky — Field Sheet | C12.S3.N00
C12.S3.N00
The Self-Reliance Library · Read the Sky

Tell Time by the Sky

No watch. No battery. No problem — three ways to read the time off the sun.
The one idea: the sun moves across the sky at a steady 15° every hour. Measure that movement and you can read the time. Your hand is the ruler.
1Shadow Stick Clock finds noon & north
shortest shadow = NOON ↑ N AM PM
  1. Push a straight stick upright into flat ground.
  2. Mark the tip of its shadow with a stone.
  3. Keep marking through the day — the shadow shrinks, then grows.
  4. The shortest shadow = local noon.
  5. At noon, the shadow points true north (N. Hemisphere).
2Hand-Width Method hours of daylight left
sun 1 hr 1 hr 1 hr arm out 4 fingers = 1 hour · 1 finger = 15 min
  1. Stretch your arm out fully toward the sun.
  2. Turn your hand sideways, fingers together.
  3. Stack hands from the sun down to the horizon.
  4. 1 hand = 1 hour of daylight left · 1 finger = 15 min.
  5. Look at the gap below the sun — never at the sun.
3Sun Arc: Morning / Noon / Evening the quick glance
EAST · morning NOON · highest WEST · evening
  1. Morning: sun low in the east, climbing.
  2. Midday: sun at its highest — due south (N. Hemisphere).
  3. Evening: sun dropping to the west.
  4. Answers the big question: plenty of light, or head back?
Do this
  • Keep your arm fully extended
  • Look at the gap below the sun
  • Use flat, level ground for the stick
Not this
  • Don't bend your elbow mid-count
  • Don't stare at the sun
  • Don't read a slope as level
Learn next: Navigating by the Sun · Building a Shadow Clock · Tracking Seasons by Sky selfreliancelibrary.com