Latitude, Longitude, and Location
Every place on Earth can be pinpointed with just two numbers. Latitude tells you how far north or south of the equator; longitude tells you how far east or west — and longitude directly determines your local time.
Practise this lesson
Three printable worksheets that build from foundations to mastery — or build your own from any module’s questions.
The Earth takes 24 hours to complete a full 360° rotation. That means the Sun appears to move 15° of longitude every hour. Sydney is at roughly 151°E longitude.
Without calculating — if noon (the Sun directly overhead) occurs at 0° longitude at some moment, how long does it take for noon to reach Sydney? What does this tell you about why Sydney's time should be roughly UTC+10?
Latitude and longitude calculations rest on two key relationships. Lock these in — both appear in HSC exam questions.
Latitude measures angular distance north or south of the equator (0° to 90°N or 90°S). Longitude measures angular distance east or west of the Prime Meridian (0° to 180°E or 180°W). Longitude determines local time — latitude does not.
Key facts
- Latitude measures north/south position; longitude measures east/west position
- Equator = 0° lat; Prime Meridian = 0° long
- Earth rotates 360° in 24 h → 15° per hour; 1° = 4 minutes
- East longitudes are ahead of UTC; west longitudes are behind
Concepts
- Why longitude determines time and latitude does not
- How to read and interpret global coordinates in (lat, long) format
- Why real time zones don't perfectly match longitude boundaries (political/economic reasons)
Skills
- Identify the hemisphere and approximate location of a place from its coordinates
- Calculate the time difference between two locations from their longitudes
- Find local time at a given longitude given the time at another location
Coordinates are always given as (latitude, longitude). The first number tells you how far north or south of the equator the place is; the second tells you how far east or west of Greenwich.
| Location | Coordinates | Interpretation |
|---|---|---|
| Sydney, Australia | 33.9°S, 151.2°E | Southern hemisphere; east of Greenwich |
| London, England | 51.5°N, 0.1°W | Northern hemisphere; almost exactly on the Prime Meridian |
| New York, USA | 40.7°N, 74.0°W | Northern hemisphere; west of Greenwich |
| Singapore | 1.3°N, 103.8°E | Just north of the equator; east of Greenwich |
| Cape Town, South Africa | 33.9°S, 18.4°E | Southern hemisphere; east of Greenwich |
What to write in your book
- Coordinates = (latitude°N/S, longitude°E/W). First = lat (N/S of equator); second = long (E/W of Greenwich).
- Latitude ranges 0°–90°; longitude ranges 0°–180°.
- 15° rule: $\Delta t = \Delta\lambda \div 15$ (hours); or $\Delta t = \Delta\lambda \times 4$ (minutes).
- East → ahead (+); West → behind (−).
- Same latitude ≠ same time; same longitude → same time (if same zone).
Did you get this? True or false: latitude determines local time, while longitude determines climate and distance from the equator.
Worked examples · 3 in a row, reveal as you go
A location has coordinates (27.5°S, 153.0°E). Describe its position and identify the approximate country.
City A is at longitude 120°E and City B is at longitude 75°W. It is 2:00 pm at City A. (a) Find the longitude difference. (b) Calculate the time difference. (c) Find the local time at City B.
A location is at longitude 105°E. It is noon (1200) at the Prime Meridian (0°). What is the local time at 105°E?
What to write in your book
- When both cities are on the same side (both E or both W): subtract the smaller from the larger to get $\Delta\lambda$.
- When cities are on opposite sides (one E, one W): add both values to get $\Delta\lambda$.
- Then: $\Delta t = \Delta\lambda \div 15$. East city is ahead; west city is behind.
- Day boundary check: if result < 0 → add 24 h (previous day); if ≥ 2400 → subtract 24 h (next day).
Quick check: A city is at longitude 135°E. Based only on this longitude, its theoretical UTC offset is:
Common errors · the 3 traps that cost marks
What to write in your book
- Latitude = climate, position N/S. Longitude = time.
- Same side → subtract longitudes. Opposite sides → add longitudes.
- International Date Line (≈180°): crossing east → lose a day (subtract 1). Crossing west → gain a day (add 1).
Fill the gap: The Earth rotates ° in 24 hours, which means it rotates ° per hour. Therefore every 1° of longitude equals minutes of time difference.
Quick-fire practice · 8 calculations
Describe the location of each place and identify its hemisphere: (a) (35.7°N, 139.7°E) (b) (23.1°S, 43.2°W) (c) (1.3°N, 103.8°E)
Two cities both have latitude 40°N. One is at longitude 74°W (New York), the other at 116°E (Beijing). Explain why they have very different climates despite being on the same latitude.
Find the time difference (in hours) between longitudes: (a) 60°E and 0° (b) 135°E and 90°W (c) 45°W and 30°E
It is 6:00 am at the Prime Meridian. Find the local time at: (a) 60°E (b) 90°W (c) 150°E
A city is at longitude 120°E. It is 8:00 pm there. What is the time at the Prime Meridian?
City P is at 45°E and City Q is at 75°W. It is 10:00 am at City P. What is the local time at City Q?
Sydney is at approximately 151°E and Los Angeles is at approximately 118°W. Using only longitude, calculate the approximate time difference. If it is 10:00 am in Sydney, estimate the time in Los Angeles.
A ship crosses the International Date Line (180°) traveling eastward (from 179°E to 179°W). Does the ship move forward or backward one day in its calendar?
Odd one out: Three of these statements are correct about longitude and time. Which one is wrong?
Earlier you were asked: if noon occurs at 0° longitude right now, how long until noon reaches Sydney (151°E)?
- Earth rotates 15° per hour.
- Time for Sun to travel 151°: $151 \div 15 \approx 10.07$ hours ≈ 10 hours 4 minutes.
- This is why Sydney's standard time offset is UTC+10 — longitude 150°E (the nearest standard meridian) gives exactly $150 \div 15 = 10$ hours.
- The slight discrepancy (151° instead of 150°) is why AEST is "approximately" UTC+10 rather than a perfect fit — politics and practicality round time zones to whole (or half) hours.
Pick your answer, then rate your confidence — that tells the system what to drill next. Each retry pulls a fresh mix from the bank.
Q1. A location has coordinates (22.3°S, 114.2°E).
(a) In which hemisphere is this location? (1 mark)
(b) Using the 15° rule, calculate the theoretical UTC offset for this longitude. (1 mark)
(c) If it is 0800 UTC, what is the local time at this location? (1 mark)
Q2. Two ships communicate by radio. Ship A is at longitude 90°E and Ship B is at longitude 45°W. It is 3:00 pm at Ship A.
(a) Find the difference in longitude between the two ships. (1 mark)
(b) Find the time difference in hours and minutes. (1 mark)
(c) Which ship is ahead in time, and what is the local time at Ship B? (2 marks)
Q3. Sydney (33.9°S, 151.2°E) and Santiago, Chile (33.5°S, 70.7°W) are often called "sister cities" because they share nearly the same latitude.
(a) Explain why Sydney and Santiago have similar climates despite being on opposite sides of the world. (1 mark)
(b) Find the total difference in longitude between Sydney and Santiago. (1 mark)
(c) Calculate the time difference using the 15° rule. (1 mark)
(d) If it is 9:00 am in Sydney (AEST = UTC+10), find the local time in Santiago using longitude only, not official time zone offsets. (2 marks)
📖 Comprehensive answers (click to reveal)
Drill answers: 1(a) 35.7°N, 139.7°E — Northern hemisphere, east of Greenwich: Tokyo, Japan; (b) 23.1°S, 43.2°W — Southern hemisphere, west of Greenwich: Rio de Janeiro, Brazil; (c) 1.3°N, 103.8°E — just north of equator, east: Singapore · 2: Latitude affects climate (distance from equator → temperature) but longitude has no effect on climate — NY and Beijing are at similar distances from the equator but climate differs due to ocean currents and continental position. · 3(a) $60÷15=\mathbf{4\text{ h}}$; (b) $135+90=225°$; $225÷15=\mathbf{15\text{ h}}$; (c) $45+30=75°$; $75÷15=\mathbf{5\text{ h}}$ · 4(a) 60°E → +4h: $0600+4=\mathbf{1000}$; (b) 90°W → −6h: $0600-6=\mathbf{0000}$ (midnight); (c) 150°E → +10h: $0600+10=\mathbf{1600}$ · 5: 120°E → 8 h ahead; PM = $2000-8=\mathbf{1200}$ (noon) · 6: $\Delta\lambda=45+75=120°$; $\Delta t=8$ h; City Q = $1000-8=\mathbf{0200}$ · 7: $\Delta\lambda=151+118=269°$; $\Delta t\approx18$ h; LA = $1000-18=\mathbf{1600}$ previous day · 8: Crossing eastward (179°E→179°W) → subtract a day (go back one calendar day)
Q1 (3 marks): (a) 22.3°S → Southern hemisphere [1] (b) $114.2 \div 15 \approx 7.6$ h → theoretical UTC+7.6 (≈ UTC+8) [1] (c) $0800 + 7\text{h}36\text{min} = \mathbf{1536}$ (3:36 pm) [1]
Q2 (4 marks): (a) $90 + 45 = \mathbf{135°}$ [1] (b) $135 \div 15 = \mathbf{9 \text{ hours}}$ [1] (c) Ship A (90°E) is east → ahead; Ship B time = $1500 - 9 = \mathbf{0600}$ (6:00 am) [2]
Q3 (5 marks): (a) Both cities are approximately 34° from the equator (same latitude), so they receive similar amounts of solar energy annually, producing similar temperature ranges and seasonal patterns (Mediterranean-type climate). [1] (b) $151.2 + 70.7 = \mathbf{221.9°}$ [1] (c) $221.9 \div 15 \approx \mathbf{14.8 \text{ h}}$ (approximately 14 h 47 min) [1] (d) Sydney (151.2°E) is east → ahead; Santiago (70.7°W) is 14.8 h behind; $0900 - 14\text{h}48\text{min} = \mathbf{1812}$ previous day (6:12 pm the previous evening) [2]
Five timed questions on latitude, longitude, and time calculations. Beat the boss to bank a tier — gold (90% + speed), silver (75%), or bronze (50%). Replays welcome.
⚔ Enter the arenaClimb platforms by answering latitude, longitude, and time questions. Pool: lesson 22.
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