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Latitude, longitude and time

తెలుగులో వివరణ

The Earth: its place, motions and interior · Part 2 / 3 · Fact-checked on 8 November 2026 · how we check

Written with AI from the sources listed at the bottom of this page, then fact-checked by a separate AI.

Latitude, the named parallels and the heat zones, India on the grid and the eight states on the Tropic of Cancer, longitude and the Prime Meridian, how longitude fixes local and standard time with worked examples, Indian Standard Time and the International Date Line.

Each idea is explained first in Telugu (తెలుగు), ending with the English and Hindi exam terms, followed by the same point in exam English. UPSC Prelims is in English or Hindi, so understand it in Telugu and revise it in English.

మొదటి భాగంలో భూమి ఎలా తిరుగుతుందో చూశాం. ఇప్పుడు రెండు ప్రశ్నలు: భూమి మీద ప్రతి చోటుకూ ఖచ్చితమైన చిరునామా ఎలా ఇవ్వాలి, అక్కడ టైమ్ ఎంత? ఇంటికి వీధి, ఇంటి నంబరు ఉన్నట్లే భూమి మీద ప్రతి స్థలానికి అక్షాంశం, రేఖాంశం అనే రెండు అంకెల చిరునామా. అరుణాచల్ ప్రదేశ్‌లో సూర్యుడు పశ్చిమ గుజరాత్ కంటే దాదాపు రెండు గంటలు ముందే ఎందుకు ఉదయిస్తాడు, భారత కాలం ఎలా నిర్ణయించారు, 180° గీత దాటిన ఓడ తేదీ ఏమవుతుంది — ఇవన్నీ ఇక్కడ. (→ English: latitude, longitude · हिन्दी: अक्षांश, देशांतर)

In exam EnglishPart 1 showed how the Earth spins and travels around the Sun. This part uses those motions to answer two practical questions: how can every place on Earth be given an exact address, and how do we know what time it is there? The answers are the grid of latitude and longitude and the rule that links longitude to time. Prelims questions draw heavily on this ground: which parallels cross India, why the Sun rises in Arunachal Pradesh almost two hours before it rises in western Gujarat, how Indian Standard Time is fixed, and what happens to the date when a ship crosses the 180° meridian. The part moves from latitude, the heat zones and India's place on the grid, to longitude and the Prime Meridian, then to local and standard time with worked examples, India's own time, and finally the International Date Line.

అక్షాంశం అంటే ఒక ఊరు భూమధ్య రేఖకు ఎంత ఉత్తరంగా లేదా దక్షిణంగా ఉందో చెప్పే కోణం. భూమధ్య రేఖ 0°, ధ్రువాలు 90°. ఈ గీతలు పూర్తి వృత్తాలు; ఉల్లిపాయ పొరల్లా ధ్రువాల వైపు చిన్నవవుతూ చివరికి బిందువవుతాయి. ముఖ్యమైనవి: కర్కట రేఖ (23½° ఉ.), మకర రేఖ (23½° ద.), ఆర్కిటిక్, అంటార్కిటిక్ వృత్తాలు (66½°). రెండు రేఖల మధ్య ఉష్ణ మండలం — నెత్తిన సూర్యుడు వచ్చేది అక్కడే; తర్వాత సమశీతోష్ణ, శీతల మండలాలు. ఒక డిగ్రీ అక్షాంశం దాదాపు 111 కి.మీ. (→ English: latitude, equator, Tropic of Cancer · हिन्दी: अक्षांश, विषुवत् वृत्त, कर्क रेखा)

In exam EnglishTo pin down any place, the globe is covered with a grid of imaginary lines. The latitude of a place is how far it lies north or south of the equator, measured as an angle in degrees from the centre of the Earth. The equator, the circle midway between the poles, is 0°, and the poles are 90°N and 90°S. Lines joining places with the same latitude are called parallels. Each is a complete circle, and they get smaller from the equator towards the poles, where the parallel shrinks to a point. Four parallels are named: the Tropic of Cancer at about 23½°N, the Tropic of Capricorn at 23½°S, the Arctic Circle at 66½°N and the Antarctic Circle at 66½°S. They split the Earth into heat zones: the torrid zone between the two tropics, the only belt that ever has the Sun directly overhead; a temperate zone in each hemisphere between the tropic and the polar circle; and a frigid zone beyond each polar circle. Because parallels are almost evenly spaced, a degree of latitude covers roughly 111 km everywhere.

The heat zones
Zone	Lies between	Overhead Sun	Example
Torrid	Tropic of Cancer and Tropic of Capricorn	Yes, once or twice a year	Southern India
Temperate (north and south)	Each tropic and its polar circle	Never	Northern India
Frigid (north and south)	Each polar circle and its pole	Never; midnight sun and polar night	Northern Norway

భారతదేశం పూర్తిగా ఉత్తరార్ధగోళంలో ఉంది: ప్రధాన భూభాగం సుమారు 8°4′ ఉ. నుంచి 37°6′ ఉ. వరకు; నికోబార్‌లోని ఇందిరా పాయింట్ ఇంకా కొంచెం దక్షిణాన. కర్కట రేఖ దేశాన్ని దాదాపు మధ్యలో దాటుతూ ఎనిమిది రాష్ట్రాల గుండా వెళ్తుంది: గుజరాత్, రాజస్థాన్, మధ్యప్రదేశ్, ఛత్తీస్‌గఢ్, ఝార్ఖండ్, పశ్చిమ బెంగాల్, త్రిపుర, మిజోరం. దాని దక్షిణ భాగంలో — మన తెలుగు రాష్ట్రాలు సహా — మధ్యాహ్నం సూర్యుడు ఏడాదికి రెండుసార్లు సరిగ్గా నెత్తి మీదకు వస్తాడు; ఉత్తర భాగంలో ఎప్పుడూ రాడు. శ్రీనగర్‌లో వేసవి, చలికాల పగళ్ళ తేడా తిరువనంతపురం కంటే చాలా ఎక్కువ — భూమధ్య రేఖకు దూరం కాబట్టి. (→ English: Tropic of Cancer, torrid zone · हिन्दी: कर्क रेखा, उष्ण कटिबंध)

In exam EnglishIndia lies wholly in the Northern Hemisphere. Its mainland stretches from about 8°4′N in the far south to about 37°6′N in the north, and the country's southernmost point, Indira Point in the Nicobar Islands, lies a little further south. The Tropic of Cancer runs roughly through the middle of the country, crossing eight states from west to east: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram. The part of India south of it lies in the torrid zone and the part to its north in the temperate zone. Climate does not follow the line neatly, though: the Himalaya blocks icy winds from the north and the monsoon carries rain to almost every region, so the country as a whole is treated as having a monsoon climate. Latitude also explains everyday differences across India. Places south of the tropic have the noon Sun directly overhead twice a year, as it passes north and then south again, while places north of the tropic never see it overhead. And the gap between summer and winter day length is much larger in Srinagar than in Thiruvananthapuram, because Srinagar lies far further from the equator.

రేఖాంశం అంటే ఒక స్థలం ప్రారంభ గీతకు ఎంత తూర్పు లేదా పడమరగా ఉందో చెప్పేది. ఈ గీతలు ధ్రువం నుంచి ధ్రువానికి వెళ్ళే సమాన పొడవు గల అర్ధ వృత్తాలు — కర్బూజా పండు మీది నిలువు చారల్లా పైన, కింద కలుస్తాయి. సున్నా గీత ఏదో ప్రకృతి చెప్పదు, అందుకే 1884 వాషింగ్టన్ సమావేశంలో లండన్ దగ్గరి గ్రీన్‌విచ్ గుండా వెళ్ళే గీతను ప్రధాన రేఖాంశం (0°)గా ఒప్పుకున్నారు. దాని నుంచి 180° తూర్పు, 180° పడమర లెక్కిస్తాం. ఉదాహరణకు న్యూఢిల్లీ సుమారు 28.6° ఉ., 77.2° తూ. (→ English: longitude, Prime Meridian · हिन्दी: देशांतर, प्रमुख याम्योत्तर)

In exam EnglishThe longitude of a place measures how far east or west it lies from a chosen starting line. Lines of longitude, called meridians, run from pole to pole. Unlike parallels, all meridians are half-circles of the same length, and they all meet at the poles, so the gap between two meridians is widest at the equator and narrows to nothing at the poles. Nature offers no obvious zero for longitude, so the starting line had to be agreed. The International Meridian Conference held in Washington in 1884 chose the meridian passing through the Royal Observatory at Greenwich, near London, as the Prime Meridian, or 0°. Longitude is counted from it up to 180° east and 180° west, and the 180° meridian is a single line reached from either side. The Prime Meridian and the 180° meridian together divide the globe into the Eastern and Western Hemispheres, much as the equator divides it into the Northern and Southern. Latitude and longitude together give every place a unique address; New Delhi, for example, lies at about 28.6°N, 77.2°E.

Parallels and meridians compared
Feature	Parallels of latitude	Meridians of longitude
Shape	Full circles	Half-circles, pole to pole
Length	Shrink towards the poles	All equal
Spacing	About 111 km per degree everywhere	Widest at the equator, zero at the poles
Zero line	Equator (natural)	Prime Meridian at Greenwich (agreed in 1884)
Range	0° to 90°N and 90°S	0° to 180°E and 180°W
Main use	Heat zones and climate	Time and time zones

భూమి 24 గంటల్లో 360° తిరుగుతుంది: గంటకు 15°, ఒక డిగ్రీకి 4 నిమిషాలు. తూర్పున ఉన్న ఊళ్ళకు సూర్యుడు ముందుగా వస్తాడు, అవి సమయంలో ముందుంటాయి. ఒక ఊరిలో సూర్యుడు అత్యంత ఎత్తులో ఉన్నప్పుడు మధ్యాహ్నం 12 — అదే స్థానిక సమయం. ఉదాహరణకు 30° తూర్పు ఉన్న చోటు గ్రీన్‌విచ్ కంటే 30 × 4 = 120 నిమిషాలు, అంటే రెండు గంటలు ముందు. ప్రతి ఊరూ తన గడియారం తనే పెట్టుకుంటే రైళ్ళ టైమ్‌టేబుల్ గందరగోళమే; అందుకే దేశం మొత్తానికి ఒక ప్రామాణిక సమయం. ప్రపంచానికి గ్రీన్‌విచ్ సమయం/UTC ఆధారం; రష్యా, అమెరికా వంటి పెద్ద దేశాలకు అనేక కాల మండలాలు. (→ English: local time, standard time, UTC · हिन्दी: स्थानीय समय, मानक समय, समन्वित सार्वभौमिक समय)

In exam EnglishLongitude and time are linked through rotation. The Earth turns through 360° in 24 hours, which works out to 15° in one hour, or 1° in four minutes. Places farther east meet the Sun earlier, so they are ahead in time, and places farther west are behind. The time set by the Sun's position at a particular place, with noon when the Sun stands highest, is called its local time; any two places on different meridians have different local times. A place at 30°E, for instance, is 30 × 4 = 120 minutes, or two hours, ahead of Greenwich. Running trains, offices and broadcasts on hundreds of local times would cause confusion, so each country adopts a standard time, the local time of one chosen meridian applied across its territory or across each of its zones. The world's reference is the time at the Prime Meridian: Greenwich Mean Time, now replaced for scientific purposes by Coordinated Universal Time (UTC), and every country states its time as so many hours ahead of or behind it. Countries that stretch across many degrees of longitude, such as Russia, the United States and Canada, use several time zones.

లెక్క ఇలా: మొదట రెండు ఊళ్ళ రేఖాంశాల తేడా, తర్వాత డిగ్రీకి 4 నిమిషాలతో గుణించు, ఊరు తూర్పున ఉంటే కలుపు, పడమర ఉంటే తీసివేయి. ఒకే వైపు ఉంటే తీసివేత (60° తూ., 90° తూ. → 30° → రెండు గంటలు); ఎదురెదురు వైపుల్లో ఉంటే కూడిక (30° ప., 45° తూ. → 75° → ఐదు గంటలు). ఉదాహరణ: చలికాలంలో లండన్‌లో ఉదయం 10 గంటలకు క్రికెట్ మ్యాచ్ మొదలైతే, మనం మధ్యాహ్నం 3.30కి టీవీలో మొదటి బంతి చూస్తాం. మన ఉదయం 9 అయితే గ్రీన్‌విచ్‌లో తెల్లవారుజాము 3.30. స్థానిక సమయంలో తూర్పు ఎప్పుడూ ముందు. (→ English: local time, time calculation · हिन्दी: स्थानीय समय, समय की गणना)

In exam EnglishA few worked examples show how the rule is applied. First find the difference in longitude between the two places, then convert it at four minutes per degree, and finally add the result if the place you want lies to the east or subtract it if it lies to the west. When both places are on the same side of the Prime Meridian, subtract their longitudes: 60°E and 90°E are 30° apart, a gap of two hours. When they are on opposite sides, add them: 30°W and 45°E are 75° apart, a gap of five hours, so when it is noon at 30°W it is 5 p.m. at 45°E. Now a practical case. Suppose a cricket match begins at 10.00 a.m. in London in winter, when clocks there follow Greenwich Mean Time. Viewers in India, whose time is 5 hours 30 minutes ahead, see the first ball live at 3.30 p.m. the same day. Turned around, 9.00 a.m. in India is 3.30 a.m. at Greenwich. Most mistakes in such questions come from mixing up the direction, so it always helps to ask first which of the two places lies to the east.

భారత ప్రధాన భూభాగం సుమారు 68°7′ తూ. (గుజరాత్) నుంచి 97°25′ తూ. (అరుణాచల్) వరకు, దాదాపు 30° రేఖాంశం. డిగ్రీకి 4 నిమిషాలు కాబట్టి తూర్పు చివర సూర్యుడు పడమర చివర కంటే దాదాపు రెండు గంటలు ముందే ఉదయిస్తాడు. అయినా దేశమంతటికీ ఒకే గడియారం: భారత ప్రామాణిక కాలం — మీర్జాపూర్ (ఉత్తరప్రదేశ్) దగ్గరి 82°30′ తూ. రేఖాంశం సమయం. 82½ ÷ 15 = 5½, కాబట్టి UTC కంటే 5 గంటల 30 నిమిషాలు ముందు; గ్రీన్‌విచ్‌లో మధ్యాహ్నం 12 అయితే మనకు సాయంత్రం 5.30. ఢిల్లీలోని CSIR-జాతీయ భౌతిక ప్రయోగశాల అణు గడియారాలతో ఈ సమయాన్ని నిర్వహిస్తుంది. ఈశాన్యంలో తెల్లవారుజామునే వెలుగు వస్తుంది కాబట్టి అక్కడ వేరే కాల మండలం కావాలనే డిమాండ్ ఉంది. (→ English: Indian Standard Time (IST) · हिन्दी: भारतीय मानक समय)

In exam EnglishIndia's mainland runs from about 68°7′E in western Gujarat to about 97°25′E in Arunachal Pradesh, close to 30° of longitude. At four minutes a degree, that means the Sun rises in the far east almost two hours before it rises in the far west. India nevertheless keeps a single time for the whole country, Indian Standard Time (IST), the local time of the 82°30′E meridian, which passes near Mirzapur in Uttar Pradesh. This meridian lies roughly in the middle of the country's east-west spread. Since 82½ divided by 15 is 5½, IST is 5 hours 30 minutes ahead of UTC: when it is noon at Greenwich, it is 5.30 p.m. in India. The country's official time is generated and maintained by the CSIR-National Physical Laboratory in New Delhi, using atomic clocks. Because daylight begins very early in the north-east, people there have long asked for a separate, earlier time zone so that offices and schools can make better use of daylight; so far the government has kept one time for the whole country.

180° రేఖాంశం దగ్గర తూర్పు లెక్క, పడమర లెక్క కలుస్తాయి; దానికి ఇటు అటు ఉన్న స్థలాల మధ్య దాదాపు ఒక రోజు తేడా. అంతర్జాతీయ దినరేఖ ఈ గీత వెంట వెళ్తూ తేదీ మారే చోటును చూపుతుంది; ఏ దేశమూ రెండు తేదీల్లో చీలకుండా భూభాగాలను తప్పించి వంకరగా వెళ్తుంది. పడమరకు దాటితే (అమెరికా నుంచి జపాన్‌కు) తేదీ ఒక రోజు ముందుకు; తూర్పుకు దాటితే అదే తేదీ రెండుసార్లు — పుట్టినరోజు రెండుసార్లు జరుపుకున్నట్లు! మొత్తంగా: అక్షాంశం ఉష్ణ మండలాలను, రేఖాంశం భ్రమణం ద్వారా సమయాన్ని ఇస్తాయి; 180° దగ్గర తేదీయే మారుతుంది. (→ English: International Date Line · हिन्दी: अंतर्राष्ट्रीय तिथि रेखा)

In exam EnglishOn the 180° meridian the eastward and westward counts meet, and a place just east of it is almost a full day behind a place just west of it. The International Date Line (IDL) runs roughly along this meridian and marks where the calendar date changes. It is not a straight line: it bends around land and island groups so that no country is split between two dates. A traveller crossing the line westward, for example from the United States towards Japan, moves the date forward by one day; a traveller crossing it eastward lives the same date twice. Seen as a whole, this part forms one chain. Latitude, measured from the equator, sets the heat zones and the special parallels that come from the tilt of the axis. Longitude, measured from Greenwich, is turned into time by the Earth's rotation, which gives local time, standard time and IST. And where the eastward and westward counts meet at 180°, the date itself changes.

Exam traps

All meridians are equal in length; parallels shrink towards the poles. The distance between meridians shrinks towards the poles, but a degree of latitude stays about 111 km.
1° of longitude = 4 minutes; 15° = 1 hour; places to the east are ahead in time.
IST is the local time of 82°30′E, which passes near Mirzapur (Uttar Pradesh), not through New Delhi; IST = UTC + 5 hours 30 minutes.
Crossing the International Date Line westward adds a day; crossing it eastward repeats a day. The line is not perfectly straight; it bends around land.
The Tropic of Cancer crosses eight states: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram. It does not pass through Odisha, Bihar or Uttar Pradesh.
For time differences, subtract longitudes when both places are on the same side of Greenwich and add them when they are on opposite sides.
The equator is a natural zero line; the Prime Meridian at Greenwich is a choice agreed at the International Meridian Conference of 1884.

Recap

Latitude: parallels from the equator (0°) to the poles (90°); tropics at 23½°, polar circles at 66½°; torrid, temperate and frigid zones.
India's mainland spans about 8°4′N to 37°6′N; the Tropic of Cancer crosses eight states and splits the country roughly in half.
South of the tropic the noon Sun is overhead twice a year; north of it, never.
Longitude: meridians of equal length; Prime Meridian at Greenwich (1884); 0° to 180° east and west.
Time rule: find the longitude difference, multiply by 4 minutes, add if the place is east, subtract if west.
15° = 1 hour, 1° = 4 minutes; IST from 82°30′E is UTC + 5:30, kept by CSIR-NPL.
India spans about 30° of longitude, so sunrise in the far east comes almost two hours before the far west; a separate north-eastern time zone has been demanded.
The International Date Line follows roughly 180°: westward crossing adds a day, eastward repeats one.

Practice questions

Q1. When it is 12 noon at Greenwich (0°), what is the local time at a place on 90°E?

6 a.m.
4 p.m.
8 p.m.
6 p.m.

Show answer

Answer: D. 6 p.m.

Each degree is worth four minutes, so 90° = 360 minutes = 6 hours. A place to the east is ahead, so its time is 12 noon + 6 hours = 6 p.m. 6 a.m. would be correct only for a place 90° west; 4 p.m. and 8 p.m. correspond to 60°E and 120°E.

Q2. Indian Standard Time is based on which meridian?

77°30′E, passing through New Delhi
82°30′E, passing near Mirzapur
88°30′E, passing near Kolkata
75°E, passing near Ujjain

Show answer

Answer: B. 82°30′E, passing near Mirzapur

IST is the local time of 82°30′E, which passes near Mirzapur in Uttar Pradesh and lies roughly in the middle of India's east-west spread; 82½ ÷ 15 gives UTC + 5:30. The other meridians are not used for IST: New Delhi lies near 77°E, and neither Kolkata's nor Ujjain's meridian is the standard.

Q3. Consider the following statements:
1. All meridians of longitude are of equal length.
2. The distance covered by one degree of longitude is the same at all latitudes.
3. The Arctic Circle lies at about 66½°N.
Which of the statements given above are correct?

1 and 2 only
2 and 3 only
1 and 3 only
1, 2 and 3

Show answer

Answer: C. 1 and 3 only

(c) is correct. Statements 1 and 3 are true: every meridian is a pole-to-pole half-circle of the same length, and the Arctic Circle is at about 66½°N. Statement 2 is false: meridians converge at the poles, so a degree of longitude is widest at the equator and shrinks to zero at the poles. Options (a), (b) and (d) all include the false statement 2.

Q4. The Tropic of Cancer does NOT pass through which one of the following States?

Odisha
Jharkhand
Mizoram
Tripura

Show answer

Answer: A. Odisha

The Tropic of Cancer crosses Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram. Odisha lies wholly south of it. Jharkhand, Mizoram and Tripura are all on the list, so those options are wrong.

Q5. Place A is at 30°W and place B at 45°E. When it is 12 noon (local time) at A, what is the local time at B?

1 p.m.
5 p.m.
3 p.m.
7 a.m.

Show answer

Answer: B. 5 p.m.

A and B are on opposite sides of Greenwich, so their longitudes add: 30° + 45° = 75°, and 75 × 4 minutes = 300 minutes = 5 hours. B is to the east, so it is ahead: 12 noon + 5 hours = 5 p.m. 1 p.m. comes from wrongly subtracting the longitudes (15°); 3 p.m. counts only B's 45°; 7 a.m. subtracts instead of adding, as if B lay to the west.

Q6. Consider the following statements:
1. Every place in the torrid zone has the noon Sun directly overhead at least once a year.
2. Places lying between the Tropic of Cancer and the Arctic Circle are in the northern temperate zone.
Which of the statements given above is/are correct?

1 only
2 only
Both 1 and 2
Neither 1 nor 2

Show answer

Answer: C. Both 1 and 2

(c) is correct. Statement 1 is true: the overhead Sun moves between the two tropics, so every place in that belt gets it at least once a year (twice for places between the tropics, once for places on a tropic). Statement 2 is true: the northern temperate zone lies between the Tropic of Cancer and the Arctic Circle. So (a) and (b) each leave out a true statement, and (d) rejects both.

Q7. A ship sailing west from Hawaii towards Japan crosses the International Date Line on a Monday. What day will it be on board just after the crossing?

Sunday
Monday again
Tuesday
Wednesday

Show answer

Answer: C. Tuesday

Crossing the date line westward moves the date forward by one day, so Monday becomes Tuesday. 'Sunday' would mean going back a day, and 'Monday again' (repeating a day) happens only when crossing eastward; 'Wednesday' would be a jump of two days, which never happens.

Q8. Match List I with List II:
List I: A. Tropic of Capricorn B. Arctic Circle C. Prime Meridian D. Meridian of Indian Standard Time
List II: 1. 0° longitude 2. 82°30′E 3. 23½°S 4. 66½°N
Select the correct answer using the code given below.

A-3, B-4, C-1, D-2
A-4, B-3, C-1, D-2
A-3, B-4, C-2, D-1
A-1, B-4, C-3, D-2

Show answer

Answer: A. A-3, B-4, C-1, D-2

The Tropic of Capricorn is at 23½°S, the Arctic Circle at 66½°N, the Prime Meridian is 0° longitude, and IST is based on 82°30′E: A-3, B-4, C-1, D-2. Option (b) swaps the tropic and the polar circle; (c) swaps the Prime Meridian and the IST meridian; (d) treats the Tropic of Capricorn as a meridian.

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Sources

NASA Science: Earth facts, the Sun, planetary fact sheets, and seasons and solstices explainers (National Aeronautics and Space Administration, US government) — https://science.nasa.gov/earth/facts/
International Conference held at Washington for the purpose of fixing a Prime Meridian and a Universal Day, October 1884: Protocols of the Proceedings — https://www.gutenberg.org/ebooks/17759
CSIR-National Physical Laboratory, New Delhi: Indian Standard Time and the time and frequency standards — https://www.nplindia.org
Survey of India, Department of Science and Technology: maps and geographical extent of India — https://surveyofindia.gov.in