Geography — Chapter 1

The Earth — Shape, Movements, Latitude, Longitude and Time

Why this chapter matters: every map question in one-paper exams hangs on this chapter — the grid, the clock and the calendar all come from it. Our verified banks hold 41 questions matching this topic directly: latitude and longitude (19) — above all the Equator, the Tropic of Cancer and the Congo’s double crossing — movements (10) — above all revolution speed, equinoxes and solstices — time zones (7) — above all Pakistan’s GMT+5 and the 1884 Greenwich settlement — and the International Date Line (5). The shape itself is taught from the lecture: banks phrase shape questions through their answers (gravity at the poles, the Equator as the longest parallel), so learn the shape section as carefully as the grid.

1. The shape of the Earth

• The Earth’s shape is a geoid — round, but not perfectly so: flattened at the poles and bulging at the Equator, like a ball of dough pressed top and bottom. The precise term is oblate spheroid: a sphere squashed at the poles. That bulge is caused by the Earth’s own rotation — spin throws the middle outward.
• The numbers that fix the shape: equatorial diameter about 12,756 km against a polar diameter about 12,714 km — the Equator is roughly 43 km wider than the pole-to-pole line. Equatorial circumference is about 40,075 km; polar circumference about 40,008 km.
• Because the poles are closer to the Earth’s centre, gravity is stronger at the poles and weaker at the Equator — the banks ask exactly this: an object weighs less at the Equator than at the poles because the force of gravity is less there.
• A globe shows the Earth truly, but a globe is costly and cannot be carried flat — so we cut and flatten it into a map. Flattening is projection, and every projection distorts something — area, shape, distance or direction — somewhere; that is why different maps exist for different purposes. The study of maps is cartography; the man who makes maps is a cartographer.
• Father of Geography: Eratosthenes — he drew a map of the world. The earliest maps came from civilisations such as the Babylonians; Eratosthenes’ own map shows its age — the Persian Gulf drawn oddly, the Caspian opening into a northern ocean, and nothing known beyond Libya.

2. The two movements: rotation and revolution

• Rotation is the Earth spinning on its own axis, west to east. One rotation makes one day — 24 hours — and gives us day and night: the half facing the Sun has day, the other half night.
• Revolution is the Earth travelling around the Sun. One revolution makes one year — 365¼ days. The extra quarter-day is why we add a leap year every four years: four quarters make one whole extra day.
• The Earth revolves at about 29–30 km per second — the banks key it as 29 km/sec, and as more than 1,600 km per minute (29.8 × 60 ≈ 1,800 km/min). The scientist who first established that the Earth revolves round the Sun was Copernicus.
• Seasons come from the tilt, not from distance. The Earth’s axis is tilted about 23.5° from the perpendicular to its orbit, and it keeps pointing the same way all year round (towards the Pole Star). As the Earth revolves, first one hemisphere leans towards the Sun and then the other — that leaning, not the changing distance, makes summer and winter. The banks ask the counterfactual too: if the Equator’s plane were not inclined to the orbit’s plane, there would be no seasons.
• Solstice means “the Sun stands still” — the two days when the Sun’s apparent northward or southward march pauses and turns:
  • Summer solstice, 21 June: the Sun’s rays are vertical over the Tropic of Cancer (bank-verified date). The Northern Hemisphere has its longest day; the Southern Hemisphere its longest night.
  • Winter solstice, 21/22 December: the Sun’s rays are vertical over the Tropic of Capricorn. The Northern Hemisphere has its shortest day.
• Equinox means day and night are equal — the two days when the Sun is vertical over the Equator itself:
  • Vernal (spring) equinox, about 21 March.
  • Autumnal equinox, about 23 September.
  • On an equinox, every place on Earth has roughly 12 hours of day and 12 hours of night — and at the Equator itself the day is 12 hours all year round (bank-verified).

3. Latitude and longitude: the grid

• His memory picture, and the one to keep: latitude lines lie flat (the lying lines); longitude lines stand. Latitude measures north or south of the Equator; longitude measures east or west of the Prime Meridian.
• Latitude (parallels): imaginary circles running east–west, parallel to the Equator. The lecture’s count is 180 latitudes. They are numbered 0° at the Equator to 90° at the poles (90°N, 90°S). Each degree of latitude is about 111 km on the ground.
  • The Equator (0°) is the largest latitude circle on Earth (bank-verified) — every other parallel is shorter, shrinking to a point at the poles.
  • The Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S) mark the farthest latitudes where the Sun can ever stand directly overhead — the limits of the Sun’s yearly march, set by the 23.5° tilt.
  • The Arctic Circle (66.5°N) and the Antarctic Circle (66.5°S) mark where the polar day and polar night begin: inside them, the Sun can stay up, or stay down, for a full 24 hours at the solstices. Note the arithmetic: 23.5 + 66.5 = 90 — the tropics and the polar circles are complements of each other.
  • The Arctic Circle passes through 8 countries: Canada, Denmark (Greenland), Finland, Iceland, Norway, Russia, Sweden and the United States (PMS Screening 2026 GK Grand Mock 15, Q59; mock-only bank rows, no mark claimed).
• Longitude (meridians): imaginary half-circles running north–south, pole to pole. The lecture’s count is 360 longitudes: 180° east and 180° west of the Prime Meridian, meeting at 180° on the far side of the world.
  • The Prime Meridian (0°) passes through Greenwich, London. It was fixed by the 1884 conference in London (bank-verified: Greenwich Mean Time was established in 1884).
  • The Equator and the Prime Meridian cross at the Gulf of Guinea, off West Africa.
  • The whole web of lines is the graticule; its projection pieces are the gore and the zone (both asked as terms).
• Rivers the banks love on this grid: the Congo River crosses the Equator twice (asked repeatedly — it loops south, then north again), and the Amazon is the river that flows both north and south of the Equator. The Tropic of Cancer itself is asked as a definition: it is an imaginary line on the globe.
• A place is fixed by reading latitude and longitude together — that pair is its address on the grid, exactly as Google Maps reads it. Pakistan’s longitudes run 61°E to 77°E.

4. Time zones: turning longitude into time

• The Earth turns 360° in 24 hours, so it turns 15° in one hour — and therefore 1° of longitude equals 4 minutes of time. That one rule answers every time-zone question.
• The world is divided into 24 time zones (bank-verified), one per 15° of longitude. East of Greenwich the time runs ahead; west of it, behind.
• Greenwich Mean Time (GMT) is the reference: noon at Greenwich is 12:00 GMT. Pakistan keeps GMT+5 — five hours ahead of Greenwich. So when it is 12 noon Pakistan Standard Time, it is 7:00 a.m. in London (bank-verified) — subtract the five hours.
• Worked examples from the lecture, all by the same rule:
  • Saudi Arabia, about 45°E, is GMT+3 — two hours behind Pakistan (75° − 45° = 30° = 2 hours).
  • New Delhi is 30 minutes ahead of Pakistan (India keeps GMT+5:30 against Pakistan’s +5:00).
  • Bangladesh, at about 90°E, is GMT+6 — one hour ahead of Pakistan.
  • Russia spans 11 time zones — the most of any country (asked).
• Local time vs standard time: local time changes with every degree of longitude, so a country picks one meridian’s time as its standard time and runs the whole country on it — that is what Pakistan Standard Time is.

5. The International Date Line: where the date turns

• The International Date Line (IDL) is the imaginary line where the date itself changes. It runs roughly along 180° longitude — exactly halfway round the world from the Prime Meridian — through the Pacific Ocean (both bank-verified).
• It is not straight: it zigzags — bending around island groups (at the Bering Strait, Fiji and Tonga among others) so that no island or country is split into two different calendar dates. The banks ask where it is located (180° longitude) and through what it passes (the Pacific Ocean); the country they name as close to it is New Zealand.
• The rule, stated without ambiguity: crossing eastbound decreases the date by one day; crossing westbound increases the date by one day. The reason is arithmetic: 180°E is GMT+12 and 180°W is GMT−12, so the two sides of the line differ by a full 24 hours.
• Why a line is needed at all: without it, a traveller circling the globe and adjusting the clock by 15° at a time would come home a whole day out. The IDL is the single correction that keeps the world’s calendar consistent.

6. Master table: the grid at a glance

7. Rapid-fire one-liners

• Shape of the Earth: geoid — oblate spheroid, flattened at the poles, bulging at the Equator.
• Equatorial diameter 12,756 km; polar diameter 12,714 km; difference ~43 km.
• Gravity is stronger at the poles, weaker at the Equator — objects weigh less at the Equator.
• Father of Geography: Eratosthenes; study of maps: cartography; map-maker: cartographer.
• Rotation: 24 hours, west to east → day and night; revolution: 365¼ days → year and seasons.
• Axial tilt: 23.5° — the cause of the seasons; Copernicus established the Earth revolves round the Sun.
• Revolution speed: 29 km/sec (more than 1,600 km per minute).
• Solstice = the Sun stands still; 21 June Sun vertical over Cancer; 21/22 December over Capricorn.
• Equinox = day and night equal; about 21 March and 23 September; day at the Equator always 12 hours.
• Latitude lies flat; longitude stands; 180 latitudes, 360 longitudes.
• Longest latitude circle: the Equator (0°); Prime Meridian: Greenwich, 0°, fixed 1884.
• Arctic Circle: 66.5°N, through 8 countries (Canada, Denmark/Greenland, Finland, Iceland, Norway, Russia, Sweden, USA).
• Equator meets the Prime Meridian at the Gulf of Guinea.
• Congo River crosses the Equator twice; the Amazon flows both north and south of it.
• 15° = 1 hour; 1° = 4 minutes; the world has 24 time zones.
• Pakistan: GMT+5, 61°E–77°E; noon in Pakistan = 7 a.m. in London.
• Russia spans 11 time zones; Saudi Arabia GMT+3; Delhi 30 minutes ahead of Pakistan.
• International Date Line: 180° longitude, Pacific Ocean; eastbound −1 day, westbound +1 day.
• Country close to the Date Line: New Zealand.

8. Most-asked facts (from our verified past-paper banks)

• The Equator as the largest latitude circle and Greenwich/1884 — the two grid facts that recur most.
• Congo crosses the Equator twice — asked in the same wording again and again; the Amazon is its companion question.
• 21 June, Sun vertical over the Tropic of Cancer — the solstice date the banks actually print.
• Equinox = day and night equal — asked as a definition, in several wordings.
• Pakistan GMT+5 and the noon-Pakistan / 7-a.m.-London conversion — the time-zone question in its standard form.
• IDL = 180° longitude, through the Pacific — asked as a location question, twice over in the banks.
• 29 km/sec revolution speed and Copernicus — the movement facts the banks key.
• 24 time zones for the world; 11 for Russia.

9. Traps & confusions

• Geoid vs sphere: the Earth is not a perfect sphere — flattened poles, bulging Equator. Any option saying “perfectly round” is wrong, even though the difference is only ~43 km across 12,700.
• Rotation vs revolution: rotation (spin, 24 hours) gives day and night; revolution (orbit, 365¼ days) gives the year and the seasons. Papers swap them deliberately.
• Seasons from tilt, not distance: the Earth is not hottest when nearest the Sun — the 23.5° tilt decides. The no-tilt counterfactual (no seasons at all) is the banks’ way of testing this.
• Solstice vs equinox: solstice = Sun stands still at a tropic (longest/shortest day); equinox = day equals night (Sun over the Equator). Do not swap the dates: 21 June = Cancer, 21/22 December = Capricorn, 21 March / 23 September = Equator.
• Tropic of Cancer vs Capricorn: Cancer is north (23.5°N), Capricorn south (23.5°S). The June date belongs to Cancer, the December date to Capricorn.
• 180 latitudes vs 360 longitudes: the lecture’s counts — latitudes are the 180 parallels, longitudes the 360 meridians (180 east + 180 west). If a paper counts the Equator twice it reaches 181 parallels; the lecture standard, and the one to answer with, is 180.
• Latitude lies flat, longitude stands: read the question’s direction — a “lying” line is latitude, a “standing” line is longitude.
• GMT+5 arithmetic: Pakistan is ahead of London, so London’s time is earlier: noon in Pakistan is 7 a.m., not 5 p.m., in London. Subtract going west, add going east.
• IDL gain/lose wording: sources phrase the gain/lose rule both ways round, so never answer from the words “gain” or “lose” alone. Use the direction: eastbound across the line, the date goes back one day; westbound, it goes forward one day. The line itself is 180°, not 0° — 0° is the Prime Meridian.
• IDL vs Prime Meridian: 0° (Greenwich) starts the time; 180° (Pacific) changes the date. They are opposite sides of the same grid.
• “Largest” without qualification means by land (the standing rule from Lecture 4) — it does not apply to the Equator, which is largest by length among parallels, not by land.

10. Memory tricks (from the lectures, plus clean professional aids)

• LAT lies flat: latitude lines lie flat across the map; longitude lines stand tall, pole to pole. One picture, and the pair never swaps again.
• 15–4–24: 15° = 1 hour, 1° = 4 minutes, 24 zones — the whole time-zone chapter is three numbers. Check: 15 × 24 = 360.
• 23.5 + 66.5 = 90: the tropic and its polar circle always add to a right angle. Learn one, get the other free.
• NEWS: the lecturer’s compass anchor from Lecture 4 — N-E-W-S round the compass — keeps east/west straight when the time arithmetic starts.
• Cancer in June, Capricorn at Christmas: the two solstice pairings in one line — June heat in the north belongs to Cancer; the December short day belongs to Capricorn.
• 180 is the date, 0 is the time: the Date Line sits at 180°, the Prime Meridian at 0° — the bigger number carries the bigger change (a whole day, not an hour).

11. Visuals (site build specs)

• DIAGRAM — The oblate spheroid: side-view Earth with the equatorial diameter (12,756 km) and polar diameter (12,714 km) labelled, poles visibly flattened and Equator bulging, with a gravity arrow stronger at the poles — placed in Section 1.
• DIAGRAM — The graticule: globe wireframe showing the Equator, both tropics, both polar circles and the Prime Meridian, with the Gulf of Guinea crossing marked — placed in Section 3.
• DIAGRAM — Tilt and the four seasons: four Earth positions around the Sun showing the 23.5° tilt, with the Sun vertical over Cancer (June), the Equator (March/September) and Capricorn (December) — placed in Section 2.
• MAP — Time zones and the Date Line: flat world strip from 0° (Greenwich) to 180° in both directions, marking GMT+5 (Pakistan), GMT+3 (Saudi Arabia), GMT+5:30 (India) and the zigzag IDL through the Pacific with New Zealand beside it — placed across Sections 4–5.

12. Practice this topic

• Practice set: 41 verified past-paper questions in the PPSC + FPSC banks are tagged to this topic’s sub-topics (latitude/longitude 19; movements 10; time zones 7; International Date Line 5) — the site serves them as this chapter’s practice set, with the IBES World Geography capsule questions behind them. The shape sub-topic has no direct question-text match in the site banks (banks phrase shape through answers, e.g. gravity at the poles) and is taught here from the lecture; the practice set filters by tags at serve time.
• Book mode: ← Previous: Treaties, Agreements & Summits · Next: Plate Tectonics & Landforms →

Goldmine Notes · Geography · Chapter 1 · Sources: TBT Geography Lecture 4, IBES Capsule World Geography, verified PPSC/FPSC past-paper banks. Standard answers only.