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1. 1.510 billion

2. Geoid

3. 3.12756 and 12714

4. Tropic of cancer

5. 82 1/2°

Correct Answer is: (c) 1:2.43

(d) Earth shaped

The time according to the longitude of a place or according to the position of sun at the place is known as the local time. In order to avoid confusion of local times many countries follow uniform time is called standard time.

• Aphelion: July 4th the earth is far from the sun and is said to be in Aphelion position. Aph means away and hellion means Sun. At this point the distance between the sun and the earth is 152 million km. 
• Perihelion: Jan 3rd the earth is nearest to the sun and is said to be in Perihelion position Peri means near, hellion means sun. At this point the distance between the sun and the earth is 147 million km.

The other names of the earth are ‘Living planet’, ‘unique planet’, ‘watery planet, ‘Blue planet’.

Correct Answer is: (c) 111 Kms

180° Meridian is supposed to pass pacific ocean but makes short detours in order to avoid land masses is known as International date line.

Define The Following:

1. Unique planet: The Earth is called a Unique planet because of its features. It is the only planet that supports life, that is why it is called “Living Planet”. The Earth is the home of all forms of life like plants, animals and human beings because of its suitable distance from the Sun, range of temperature, life supporting gases, atmosphere, water cycle etc.,

2. Size of the Earth: The Earth is the fifth largest planet in the Sun’s family. The diameter of the Earth is approximately 4 times greater than the Moon and it is around 107 times less than that of the Sun. The total geographical area of the Earth is 51 Omillion sq.kms

3. Geoid: The Earth’s shape is often described as Geoid, which literally means ‘Earth shaped’, or ‘Oblate spheroid’. The Earth is flattened at the poles and bulges at the equator. The Equatorial diameter of the Earth is 12756 kms and the Polar diameter is 12714 kms Equatorial circumference40,076 kms and Polar circumference-40,008 kms. The difference of 42 kms in diameter is the proof for regarding the Geoid shape of the Earth.

4. Continents: The land bodies of the Earth are known as Continents. There are seven continents, namely Asia, Africa, North America, South America, Antarctica, Europe and Australia. The continents are land masses of large size. Asia is the largest continent in the world while Australia is the smallest continent in the world.

5. Prime Meridian: Line of longitude are called Meridians (meri-mid and dian -day) because all places along the same meridian of longitude experience noon or midday at the same time.The meridian passing through Greenwich (England) has been chosen as Prime Meridain. It is marked as 0° longitude.

6. Indian Standard Time: In India, 82 1/2° East longitude is considered as the Standard Meridian of the country. It passes through Allahabad of Uttar Pradesh. The time based on this Meridian is called the Indian Standard Time (1 ST). It is 5 hours and 30 Minutes ahead of G.M.T.

Jan 3rd the earth is nearest to the sun and is said to be in Perihelion position. Peri means near, hellion means sun. At this point the distance between the sun and the earth is 147 million km.

1. Oceans

2. Northern Southern

3. Latitude

4. Midday

5. Arctic

(d)Tropic of cancer.

Correct Answer is: (a) 1ST

There are mainly two motions of the Earth – daily rotational speed and annual revolution speed.

(d) Standard time

To know the position, distance and west or north and south, a network of lines are drown on the globe. These are called lines of latitudes and longitudes.

There are four major oceans they are pacific ocean, the Atlantic ocean, the Indian ocean and Arctic Ocean.

The average distance between Sun and Earth is 150 million kilometers.

Earth’s volume is 416 million cubic kms, while the Earth’s average density is 5.517 grams per cubic cm.

Correct Answer is : (a) Russia

The horizontal lines are the lines of latitudes and the vertical ones are called lines of longitudes. These lines intersect each other at a right angles and create a network called grid or graticule.

When the sun is at the least distance (147 million km) from the Earth, then such a situation is called the perihelion.

The orbit of the Earth is not circular, it is elliptical, due to which the distance between the Sun and the Earth varies.

Due to the centrifugal force generated by the motion of the Earth, the earth protrudes more on the equatorial region and is flattened on the poles.

The 23 1/2 South latitude line, which is found in the southern hemisphere, is called the Tropic of Capricorn.

The 23 North latitude line found in the northern hemisphere is called the Tropic of Cancer.

The angular distance between the meridian line passing through any point on earth and the prime meridian line, is the longitude of that point.

On March 21, the sun’s position is on the equator. In this situation, the length of day and night on Earth is almost equal. In the Northern Hemisphere, the spring season starts from. March 21. Hence it is called Spring Equinox.

The 180° longitude line, located in the opposite direction of the prime meridian (0° longitude), is called the International Date Line. If we circumnavigate the entire world, our clock undergoes a difference of 24 hours (180° East – 180° West), thus there is a difference of 1 day in both places. The journey from east to west will decrease one day and the journey from West to East will increase one day. In order to overcome this difficulty, different nations have unanimously determined the international date range with reference to the 180° longitude line.

Importance of International Date Line: Taking reference from the International Date Line, the date is determined all over the world. 

Its importance can be understood through the following points:

1. This line removes the variation in time of 1 day that occurs upon circumnangating the earth, out to be revolving around the world-which is the difference of one day. 

2. Due to the assumption of daybreak (dawn) in accordance to this line, the determination of the day in the world becomes simpler. 

3. Travelling from east to west of the international date line, time decreases by 1 day. While travelling from west to east, one day increases. 

4. If the international date line is not determined, then the same date cannot be found across the world.

The line drawn in north – south direction which passes through Greenwich, located near London, is called the prime meridian or the Greenwich meridian.

(c) 180° longitude

Aryabhatta described the earth to be round like a ball and rotating from the west to east direction on its axis, creating night and day.

The place which is on the west of this line, i.e., towards Asia, if Monday begins for it, then it is the beginning of Sunday for places to its east, i.e., America. When a ship crosses this line and heads towards the United States, they cross the line on Sunday, they will and if they cross this line moving towards Asia, then take out one day from the calendar. That is if cross the line on Sunday, the next day will be Tuesday and not Monday.

The time of each place according to its longitude is called the local time can be determined precisely by the sun’s overhead position. This time the sunlight can tell exactly. The local time is related to the height of the mid – day sun. From this, on the same longitude, all cities in the North – South have the same time. So there is no difference in their local time. The cities located in the East – West will be on different meridian lines. For this reason they will have different times. This is the reason that the local time of the cities located in the East – West have a natural difference. Local time is always in accordance with the midday sunlight.

0°-90° latitudes are found on the globe from the equator to the north and south poles.

These latitudes are divided mainly into the following parts:

1. Low Latitudes: The lower latitudes are said to be between the 30° North and the 30° South Hemisphere from the equator (0° latitude line). 

2. Intermediate latitudes: The area between 30° – 60° North and South latitudes on the globe are called intermediate latitudes. 

3. High Latitude: The region between 60° – 90° North and South latitudes on the globe are called high latitudes.

In relation to the origin of the Earth, important information is found in Indian texts. In the book ‘Aryabhatiya’ written by Aryabhatta, the earth is said to be spherical. Great Indian astrophysicist Aryabhatta said that the earth is round like a ball and spinning on its axis from west to east direction, creating night and day. Aryabhata and Bhaskaracharya – (II) presented scientific facts about sun and lunar eclipses and gravitation, which could only known to the European people in the 15 – 16^th century, A.D.

The earth is not at right angles to its axis, but is inclined at 23 . This 23 inclination remains in the same direction during its orbit of the sun. As a result of this inclination of the earth, the north and the south pole come near the sun alternately, resulting in the enjoyment of different seasons in both the hemispheres. If this axial tilt was not there then day and night durations would be equal on earth and it would be impossible to have different seasons.

The rotation of the Earth on its axis is called daily or rotational speed. The earth completes one rotation by rotation of on its axis in 24 hours. The rotation of earth night. This motion of the Earth is from west to east. On the side of the Earth facing the Sun, there is east day and on the other part. Due to the rotation of the Earth from west to east, Sun rises in the east and sets in the west.

Because of the spinning of Earth from west to east, the direction of the spinning of all the constellations and stars remains from east to west direction. Due to this motion of the Earth, there is more protuberance in the equatorial region and on the equator on poles. Apart from this, there is a change in the direction of wind and ocean currents due to this speed. This rotation of the Earth is at approximately 1600 km per hour, at 45° north and south latitude, it is 1,120 km/hr and at poles it becomes almost zero.

Normal solar days are longer and sometimes smaller than mean solar day. The difference in their time is called time Equation.

Mean time: In daily practice, clocks are often not adjusted ahead of time or behind time. This means that the watches do not show the observable time according to the Sun, but they show the mean – time. Thus, the known time is not taken to be the real time and the duration of the given day is also different. However, if the period of all such days of the year is added and their average is calculated, then the real day period will be detected. This received day is the mean time. The time we use, is based on this. Our watches run according to this mean time. This time it is also called Clock Time.

Longitudes are the angular lines drawn in north – south direction on the globe. They have the following characteristics:

1. The longest distance between the longitudes is on the equator. 

2. On moving towards the poles from the equator, the distance between longitudes decreases. 

3. All the longitudes on the poles. 

4. Distance between latitudes on the equator is 111 km, on 30° north and south latitudes 96.5 km, on 60° north and south latitudes it is 55.4 km, and on 80° north and south latitudes it is 19.3 km and at 90° north and south latitude, it is zero. 

5. There is a difference of 4 minutes on each longitude. 

6. All 360° longitude lines when convert into a circle, they become greater circles.

The equator divides the earth into two equal hemispheres – Northern and Southern Hemisphere. Determination of latitudes is parallel to the equator in the north and south directions. Their angles are determined from the center of the Earth. These Latitude circles become smaller away the equator towards the north and south directions towards the poles. The equator is 0° and the poles are at 90° latitude.

Thus 90° latitude is found in the northern hemisphere and 90° latitude in the southern hemisphere. The distance between any two consecutive latitudes is 111 km, which is slightly higher at very high latitudes due to their flattening on the poles. To get the exact position of a place, the degree is divided into minutes and minutes into seconds. According to the location of a place, its northern latitudes and southern latitudes are determined.

The speed of the sun is not always the same. It is sometimes affected behind and ahead from the apparent time. If the sun is perpendicularly overhead some time after the clock strikes 12 O’clock then the time equation will be positive (+) and if the sun is shining vertically overhead before the clock shows 12 o’clock, then the time equation is negative (-). Only four dates of the year are such, when the observable time and mean time are the same. These four dates are April 16, June 15, September 1 and December 25. During these dates, the time equation is zero (0).

Equation of time: The time within which a place is rotated on the axis in one complete rotation and then comes back to the same position, so that the sun begins to shine above it, is called a Solar day. But the Earth’s orbit is not circular, but it is elliptical. At the same time, the position of the Sun is not centered. As a result the earth reaches. When there is winter season in the Northern Hemisphere, then the Earth is relatively close to the Sun, which is called Perihelion.

On the contrary, when it is summer in the northern hemisphere, the Earth is relatively far from the Sun and we call it Aphelion. It is worth noting that the change of the seasons does not depend on the distance of the sun. It is related to the height of the sun’s in sky. i.e. the angular position of the rays obtained and the thermal power obtained from them. When the earth is in a perihelion state, As revolution speed becomes faster. In contrast, the period of Solar – Day (the time between two actual position) decreases – So two types of time are experienced.

When the sun shines perpendicularly a longitudes, then it is the mid – day time at twelve o’clock in the places located on that line. According to them, the time that the clock keeps at mid-day, then the sun will not be vertical. It will be tilted away from this position because the speed of the sun does not always remain the same. Due to this variation (decrease – increase), Solar – Day is not convenient for time measurements. Solar – clock is used to know the time through the sun. According to the condition of the sun, we have to take the trouble to keep the time in its accordance, because the clock needles need to be moved forward or backward every day, according to the sun.

As a result of the earth’s rotation from west to east cause change in the direction of winds. The direction of the winds is deflected towards their right in the northern hemisphere and towards their left the southern hemisphere.

When we observe the horizon from a hill top or from the deck of a ship, it is always circular in shape. It widens with increasing altitude. This could be so only in a spherical body.

The distance between places on the Earth was first calculated by Greek Philosopher Eratosthenes.

If a ship starts sailing from a point, moving constantly in the same direction, it reaches the same point form where it has started its journey. This shows that the earth is spherical in shape.

The Bedford level canal Experiment conducted by Dr. A.R. Wallace, also proves that the earth is spherical in shape, in this experiment three poles of equal height Were fixed in a straight line at an equal distance of one mile from one another over a stretch of water in a canal. When the poles observed through a telescope, the middle pole appeared to be higher then the other two poles because of the curved surface.

Dr. Alfred Russel Wallace conducted Bed ford level Experiment in 1956, along the Bed ford level canal area in Britain.