Direction and Location
Primary 6 · Social and Religious Studies
Direction and Location
Lesson 4 of 4
15 min
Mutesi's uncle lives in Nairobi. One evening he calls: "Good evening! It is already 8 o'clock here, and the children are asleep." Mutesi looks at the clock on the wall in Kigali. It says 7 o'clock. "How can it be a different time in Nairobi?" she asks. "We are on the same continent!"
The Earth spins on its axis from west to east, once in about 24 hours. As it turns, one side faces the sun (day) and the other side is in darkness (night). Places further east turn towards the sun first, so they see sunrise, midday and sunset earlier than places to the west.
A full turn of the Earth is 360°, and it takes 24 hours:
Worked example 1
Town A is at 30° E and Town B is at 60° E. The difference is 60 − 30 = 30°. 30 ÷ 15 = 2, so there are 2 hours between them. B is further east, so B is ahead. When it is 8:00 a.m. at A, it is 10:00 a.m. at B, by the sun.
Worked example 2
Kigali is at about 30° E and Greenwich is at 0°. The difference is 30°, or 2 hours. Greenwich is to the west, so it is behind. When the sun says 8:00 a.m. in Kigali, it says about 6:00 a.m. at Greenwich.
The rule: going east, add time; going west, subtract time.
If every town used its own sun time, even two nearby towns would have slightly different clocks. So the world is divided into time zones, each roughly 15° wide, and everyone in a zone uses the same clock time. Time zones are counted from UTC (Coordinated Universal Time), the time at the Prime Meridian, which used to be called Greenwich Mean Time (GMT).
| Time zone | Difference from UTC | Used in |
|---|---|---|
| West Africa Time | UTC + 1 | Western DR Congo (Kinshasa) |
| Central Africa Time (CAT) | UTC + 2 | Rwanda, Burundi, eastern DR Congo |
| East Africa Time (EAT) | UTC + 3 | Uganda, Kenya, Tanzania |
So when it is 10:00 in Kigali, it is 11:00 in Nairobi, Kampala and Dodoma, 10:00 in Gitega and 9:00 in Kinshasa. Ghana uses UTC all year, so it is 8:00 in Accra.
Did you know? UTC + 2 is the time at 30° E, and 30° E runs right through Rwanda. That is why our clocks match the sun so well: in Kigali the sun is highest in the sky at around midday.
Tip
East is ahead, because the sun says "good morning" to the east first. Going east, add 1 hour for every 15°. Going west, take away 1 hour for every 15°.
Answer: 15°.
Answer: 4 minutes.
Answer: 10:00, because Uganda uses UTC + 3, one hour ahead of Rwanda.
Answer: 45 − 15 = 30°, which is 2 hours. Q is to the west, so it is behind: 10:00 a.m.
Answer: 19:00, because Kigali is 2 hours ahead of UTC.
What you learned today
Sources and credits
The worked examples are written by Ganzaa.
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
Quick check
