Earth - Basics, Latitudes & Longitudes

By Sudarshan Gurjar

Which one of the following is the continent with the highest mean elevation in the world? [1995]

(a) Antarctica (b) North America(c) Asia (d) South America

If the earth's direction of rotation is reversed, what should be the IST when it is noon at the International Date Line? [1997]

(a) 06.30 hrs (b) 05.30 hrs(c) 18.30 hrs (d) 17.30 hrs

Which one of the following stars is nearest to the Earth? [1997]

(a) Polaris (b) Alpha Centauri(c) Sun (d) Sirius

Along which one of the following meridians did India experience the first light of the sunrise of the new millennium? [2000]

(a) 2°30' W (b) 82°30' E(c) 92°30' W (d) 92°30' E

Who amongst the following was the first to state that the earth was spherical ? [2001]

(a) Aristotle (b) Copernicus(c) Ptolemy (d) Strabo

Consider the following statements: [2005]

1. The Axis of the earth's magnetic field is inclined at 23 and half to the geographic axis of the earth.2. The earth's magnetic pole in the Northern Hemisphere is located on a Peninsula in Northern Canada.3. The earth's magnetic equator passes through Thumba in South India.

Which of the statements given above is/are correct?(a) 1, 2 and 3 (b) 2 and 3(c) 2 only (d) 3 only

Consider the following statements: [2005]

1. Total land area of earth is approximately 1475 lakh square kilometers.2. Ratio of land area to water area of earth is approximately 1 : 4.3. Maximum percentage of earth's water is in the Pacific Ocean.

Which of the statements given above is/are correct?(a) 1 and 3 (b) 2 and 3(c) 1 only (d) 3 only

In the structure of planet Earth, below the mantle, the core is mainly made up of which one of the following? [2009]

(a) Aluminium (b) Chromium(c) Iron (d) Silicon

Consider the following factors: [2012 - I]

1. Rotation of the Earth2. Air pressure and wind3. Density of ocean water4. Revolution of the Earth

Which of the above factors influence the oceancurrents?(a) 1 and 2 only (b) 1, 2 and 3(c) 1 and 4 (d) 2, 3 and 4

Variations in the length of daytime and night time from season to season are due to [2013 - I]

(a) the earth’s rotation on its axis(b) the earth’s revolution round the sun in an elliptical manner(c) latitudinal position of the place(d) revolution of the earth on a tilted axis.

Consider the following pairs: [2013 - I]

1. Electromagnetic radiation2. Geothermal energy3. Gravitational force4. Plate movements5. Rotation of the earth6. Revolution of the earth

Which of the above are responsible for bringingdynamic changes on the surface of the earth?(a) 1, 2, 3 and 4 only (b) 1, 3, 5 and 6 only(c) 2, 4, 5 and 6 only (d) 1, 2, 3, 4, 5 and 6

Which of the following phenomena might have influenced the evolution of organisms? [2014 - I]

1. Continental drift2. Glacial cycles

Select the correct answer using the code given below.(a) 1 only (b) 2 only(c) Both 1 and 2 (d) Neither 1 nor 2

The standard time of the following countries is ahead of or behind Greenwich Mean Time depending on whether they are East or West of the longitude passing through Greenwich.

(1) Cuba (2) Greece(3) Iraq (4) Costa Rica (5) Japan

Which one of the following sequential order gives the correct arrangement of the countries according to their standard time from ahead to behind GMT?

(a) 5,3,2,1,4 (b) 2,4,1,3,5(c) 4,1,3,2,5 (d) 3,5,4,1,2

By Sudarshan Gurjar

Which one of the following Straits is nearest to the International Date Line?

(a) Malacca Strait(b) Bering Strait(c) Strait of Florida(d) Strait of Gibraltar

By Sudarshan Gurjar

The local time of a place is 6:00AM when the Greenwich Mean Time(GMT) is 3:00AM, What is the longitude of the place?

(a) 45°West (b) 45°East (c) 120°East (d) 120°West

By Sudarshan Gurjar

The time Cairo is 2 hours ahead of Greenwich. Hence it is located at-

(a) 30°W longitude (b) 30°E longitude (c) 28°E longitude (d) 28°W longitude

By Sudarshan Gurjar

By Sudarshan Gurjar

By Sudarshan Gurjar

By Sudarshan Gurjar

Geography literally means description of Earth.

Greeks are supposed to be the first geographers and it was Eratosthenes who coined the wordGeography.

Alexander von Humboldt (1769–1859) – considered father of modern geography, published Cosmos.

The earliest Greek known to have made a map of the world was Anaximander.

By Sudarshan Gurjar

Shape of the Earth

In 1687 Sir Isaac Newton suggested that round earth along with other planets could not be perfectly spherical.

Until the time, the spherical perfection model was a basic assumption of Geodesy.

By Sudarshan Gurjar

By Sudarshan Gurjar

It is a science that attempts to determine earths shape & size by surveys & mathematical calculations.

The Earth is slightly mis-shaped because of its Spinning.

It Bulges (Centrifugal force) near the equator & it is flattened nearthe poles.

Oblate Spheroid

Today, the earth is considered as a Geoid.

Means that The Shape of Earth is Uniquely Earth shape.

Polar Diameter- 12714 km(Flattened)

Equatorial Diameter-12756 km(Bulge)

The difference between these two is 0.3 percent`

By Sudarshan Gurjar

By Sudarshan Gurjar

Evidence of the Earth's , Sphericity

Circum-navigation of the earth

Ship’s visibility

The lunar eclipse

Planetary bodies are spherical

Aerial photographs

Sunrise andSunset

By Sudarshan Gurjar

Latitude Latitude is the angular of a point on the earth’s surface. measured in

degrees from the center of the earth. Parallel: A line connecting all points having same latitude is called

parallel, because it is parallel to all lines of latitude.

By Sudarshan Gurjar

Great Circle : Any Plain i.e. passed through the center of a sphere bisects that sphere & creates a great circle.

Of all the parallels equator alone make a great circle.

Circles, becoming smaller pole wards.

The equator represents 0° and the North and South Poles are 90°N.and 90°S

The most important lines of latitude are the equator, the Tropic ofCancer (23°N,). the Tropic of Capricorn (23°S.). the Arctic Circle(66°N.) and the Antarctic Circle (66°S.).

By Sudarshan Gurjar

By Sudarshan Gurjar

By Sudarshan Gurjar

Longtitude Longitude is an angular distance , measured in degrees along the equator

east or west of the Prime Meridian

Longitude are series of semi-circles that run from pole to pole passingthrough the equator. Such lines are also called meridians .

It was decided in 1884, by international agreement, to choose as the zeromeridian the one which passes through the Royal AstronomicalObservatory at Greenwich, near London.

Prime meridian (0°) from which all other meridians radiate eastwards andwestwards up to 180.

By Sudarshan Gurjar

By Sudarshan Gurjar

LONGITUDE AND TIME As the earth rotates from west to east,

Those places east of Greenwich will be ahead of Greenwich time and those to the west will be behind it.

The rate of difference can be calculated as

The earth rotates 360° in about 24 hours, which means 15° an hour or 1° in fourminutes.

Thus, when it is 12 noon at Greenwich, the time at 15° east of Greenwich will be 15 4 =60 minutes, i.e., 1 hour ahead of Greenwich time,

which means 1 p.m. But at 15° west of Greenwich, the time will be behind Greenwichtime by one hour, i.e., it will be 11.00 a.m.

By Sudarshan Gurjar

Similarly, at 180°, it will be midnight when it is 12 noon at Greenwich.

Since the earth makes one complete revolution of 360° in one day or24 hours, it passes through 15° in one hour or 1° in 4 minutes.

We may thus conclude that places east of Greenwich see the sunearlier and gain time, whereas places west of Greenwich see the sunlater and lose time

IST (Indian Standard Time)-82.5E Meridian - 5.5 ahead of GMT

By Sudarshan Gurjar

By Sudarshan Gurjar

By Sudarshan Gurjar

By Sudarshan Gurjar

By Sudarshan Gurjar

By Sudarshan Gurjar

British launched Chaibagaan Time (1 Hrs Ahead of IST) 150 years ago in Assam.

By Sudarshan Gurjar

The International Date Line

By Sudarshan Gurjar

The International Date Line where the date changes by exactly one day whenit is crossed.

A traveller crossing the date line from east to west loses a day(because of the loss in time he has made)

And while crossing the dateline from west to east he gain a day(because of the gain in time he encountered).

The International Date line in the mid-Pacific curves from the normal180 degree meridian at the Bering strait ,Fiji and other island to preventconfusion of day and date in some of the island groups that are cut throughby the meridian.

By Sudarshan Gurjar

By Sudarshan Gurjar