SOLAR SYSTEM

The solar system comprises the sun and its eight planets which are believed to have been developed from the condensation of gases and other lesser bodies

THE SUN

i. The sun is in the centre of the planetsii. The sun is stationary while all the planets move around it.

iii. The sun is the largest stariv. The surface of the sun called photosphere has temperature of 6000o C and increases to 20

million in the interiorv. All over the surface of the sun is fiery gases that leap up in whirls of glowing flames

vi. It is the source of light and energy to all the planets

PLANETThe word planet is derived from a Greek word for “wanderer”, a name given to any celestial object that appears to roam the sky. A new draft definition by the International Astronomical Union (2006) says that an object qualifies to be a planet if it satisfies three requirements: the object must be large enough to the extent that its own gravity has moulded it into a roughly spherical shape and it must not share its orbit with asteroids and other debris. This disqualifiesPluto whose oblong orbit overlaps Neptune’s, downsizing the solar system. On this reason, Pluto is considered as a dwarf planet.

POSITION OF PLANETS RELATIVE TO THE SUNMercury, Venus, Earth and Mars are considered as inner planets while Jupiter, Saturn, Uranus and Neptune form the outer planets.

DIAGRAM SOLAR SYSTEM

THE PLANETS AND THEIR CHARACTERISTICS

MERCURYi. Mercury is the smallest, hottest and closest to the sun.

ii. Mercury has a distance of 57900 000km or 36 million miles away from the sun.iii. It thus completes its orbit in a much shorter space of time.iv. A year in Mercury is only eighty eight days. This means it takes 88 days to complete one

orbit or revolution.v. It has no living thing due to the high surface temperature.

vi. It has no satellite.

VENUS

i. Venus is the next closest to the sun.ii. It is often considered as Earth’s twin because of their close proximity in size mass

(weight) and density.iii. It takes Venus 225 days to complete one revolution.iv. Venus has no satellite.v. Its distance from the sun is 107, 200,000km.

vi. Venus has no living things.

EARTHi. Earth is the only planet which has life and all the living things.

ii. It has one natural satellite, the moon that revolves around the earth once in every 27 days.iii. The earth takes 365 ¼ days to complete its orbit.iv. The distance from the moon to the earth is 384 629 km (238900 miles)v. The actual distance between the sun and the earth is 148,800, 000km

MARSi. It is the fourth planet from the sun.

ii. It is believed to be the next planet after Earth to have the possibility of some plant life.iii. Mars has dark patches on its surface.iv. It has two satellites.v. It takes 687 day to complete one orbit or revolution.

vi. The distance between mars and the sun is 227, 200, 000 km.

JUPITERi. Jupiter is the largest planet in the solar system.

ii. Its surface is made up of many gases such as hydrogen, helium and methane.iii. It has circular lights and dark bands.iv. Jupiter has twelve satellites that circle round it.v. Its surface is very cold, probably about -128o C (-200o F)

vi. Its distance from the sun is 772, 800, 000 km.vii. Jupiter has a diameter of about 134,700 km,

viii. Jupiter takes about 11.9 years to complete its orbit round the sun.

SATURNi. Saturn is the second largest planet.

ii. It takes 29 ½ years to complete its orbit.iii. Saturn has three rings and nine satellites around it.iv. The distance between Saturn and the sun is 1,417, 600

URANUS

i. Uranus orbits around the sun in a clockwise direction from East to West.ii. It has five satellites revolving around it.

iii. Uranus takes 84 years to complete its orbit.iv. Its distance from the sun is 2, 854,400, 000 km.v. Uranus is 50 times larger than the Earth and 15 times as heavy.

NEPTUNE

i. Neptune has only two satellites.ii. It is very cold because it is far from the sun.

iii. Its distance from the sun is 4, 468,800,000km.iv. It takes about 164.8 years for Neptune to complete its orbit.v. It closely resembles Uranus.

THE ORBITIt refers to the path followed by each planet around a planet. The planets revolve around the sun in elliptical orbit

COMETS, ASTEROIDS, METEORS AND SATELLITES

COMETS

Comets are small icy bodies that come and go from the inner parts of the solar system in elongated orbits at random orientations to the ecliptic.….. They move around the sun usually at a great distance from it (the sun) and are seen only rarely from the earth even then as a bright line in the sky.

ASTEROIDS

They are rocky objects varying in width from over 900 kilometers to less than one kilometer that circle the sun mostly between the orbits of Mars and Jupiter. Asteroids are also known as minor planets.

METEORS

Meteors are pieces of rock or other matter in space that produce bright light as they travel close to the earth.

SATELLITE

It refers to a small or minor body orbiting a planet or larger body in space. The moon for example is the natural satellite of the Earth. Many artificial satellites have in recent years been sent up into space by scientists to travel round the earth and other planet.

THEEARTH AS A PLANET

THE SHAPE OF THE EARTH

In the olden days, sailors fear to venture far into the distant ocean because they thought the earth was as flat as a table. They thought that, when they reach the edge of the earth, they would slip down and perish in bottomless ocean. This is of course, not true. From years of accumulated knowledge, experience and observations in different parts of the world, we know that the earth is round.

It’s spherical shape is an established fact, proved and accepted by all. There has been so much research done on earth science that it various dimensions have been accurately found. Its equatorial diameter is 12761km (7926miles), equatorial circumference is 40084km (2489miles). Polar diameter is shorter by 42km (26miles). This simply shows that the earth is not a perfect sphere. It is a little flattened at both ends like an orange. It can in fact be called a geoid (earth-shaped)

EVIDENCE (PROOFS OF THE EARTH’S) SPHERICITY

There are many ways to prove that the earth is spherical. The following are some of them.

1. Circumnavigation of the earth: The first voyage around the world by Ferdinand Magellan and his crew, from 1519 to 1522, proved beyond doubt that the earth is spherical. No traveller going round the world by land or sea has ever encountered an abrupt edge, over which he would fall. Modern air routes and ocean. Navigation are based on the assumption that the earth is round

DIAGRAM

2. The circular horizon: The distant horizon viewed from the deck of a ship at sea or from a cliff on land is always and everywhere circular in shape. This circular horizon widens with increasing altitude and could only be seen on a spherical body

DIAGRAM3. Ship’s visibility: When a ship appears over the distant horizon, the top of the mast is seen

first before the hull. In the same way, when it leaves habour, its disappearance over the curve surface is equally gradual. If the earth were flat, the entire ship would be seen or obscured all at once.

DIAGRAM4. Sunrise and sunset: The sun rises and set at different times in different places. As the

earth rotates from west to east, places in the east see the sun earlier than those in the West. If the earth were flat, the whole world would have sunrise and sunset at the same time. But this is impossible because the earth is not flat in shape.

DIAGRAM5. Planetary bodies are spherical. All observations from telescopes reveal that the planetary

bodies, the sun, moon, satellites and stars have circular outlines from which every angle you see them. They are strictly spheres. Earth, by logic, cannot be at the only exception

DIAGRAM

6. Driving poles on level ground on a curved earth: Engineers when driving poles of equal length at regular intervals on the ground have found they do not give a perfect horizontal level. The centre pole normally projects slightly above the poles at either end because of the curvature of the earth. Surveyors and field engineers therefore have to make certain corrections for this inevitable curvature.

DIAGRAM7. The lunar eclipse: The shadow cast by the earth on the moon during a lunar eclipse is

always circular. It takes the outline of an arc of a circle. Only a sphere can cast such a circular shadow.

DIAGRAM8. Space photographs: Pictures taken from high altitudes by rockets and satellites show

clearly the curved edge of the earth. This is perhaps the most convincing and the most up-to-date proof of the earth’s sphericity.

THE EARTH’S MOVEMENT

The earth is held in space by the combined gravitational attraction of other heavenly bodies. The earth moves in space in two principal ways: The two principal motions are: The rotation of the earth on its own axis and the revolution of the earth around the sun in an orbit.

ROTATION OF THE EARTH

Rotation refers to the movement or the turning of the earth on its own axis. The earth’s rotation is an anti-clockwise direction that is from west to east (left to right) once in every 24hours or one day. During rotation, the earth’s axis is inclined at an angle of 231/2 to the vertical. The earth takes 24 hours to complete one rotation. The speed of the rotation is approximately 4.7km per second at the equator and 2.3km per second at latitude 600. Thus, the earth takes one day to turn through 360o of longitude. The earth rotates through 15 in every one hour.

Thus, if 24 hours = 360o

1hour = 1 × 360 o

24

= 15o

A DIAGRAM ON ROTATION

[Hint] The earth’s axis is an imaginary line that passes through the centre of the earth. The ends

Of this axis of rotation are North and South poles

EFFECTS OF EARTH’S ROTATION

1. The rotation of the earth causes day and night: The rotation causes certain part of the earth to face the sun at a particular time whiles the other part in shadow at the same time since it is turned away from the sun. This happens because of the stationary of the sun and also the spherical nature of the earth. The potion that faces the sun experience day and the portion in the shadow experience darkness.

2. The rotation causes a difference of one (1) hour between two parts of 15o apart in longitude. In every one hour, the earth turns through 15o of longitude. This means that places with 15o of longitude between them will have a difference of 1hour in their time. The earth rotates from west to east and so places at the east see the sun first before places at the west. This implies that areas in the east is ahead the time and places in the west to be behind.

3. Rotation causes sunrise and sun set: As the earth rotates from west to east, portion of the earth in darkness in the west rotates to the east to face the sun which we called sunrise. Since rotation continues, the sun will be overhead at noon. The rotation will continue until the portion will be in the evening and finally rotation will carry that portion back to darkness in west and it is called sunrise.

4. Rotation causes daily rise and fall of the tides. Tide is the periodic rise and fall of the level of seas and ocean waters. Tide is caused by the gravitational force or pull of the moon and the sun. Because of the remoteness of the sun, its pull is not as great as the moon. As the earth rotates, the water bodies on the part of the earth facing the moon quickly piles up. Ocean waters at the opposite side facing the moon also pile up. When this happens, we say that, two sides have high tides. The high tides occur in the mornings and evenings. The opposite sides of the earth that are not facing the moon have low tides. This does not occur simultaneously because the earth is not flat and this rotating all the time. Low tides are experienced around mid-days and mid-nights. Within one day the fall and the rise of the tides happens twice each.

5. Rotation leads to deflection of winds and ocean currents: Rotation of the earth causes the winds and ocean current to change their natural direction. Those in the Northern Hemsiphere are deflected to the right and those in the southern Hemispere to the left. The coriolis or geostrophic force causes the deflection and the law explaining the direction to the right or left is known as the Ferrel’s law.

6. Rotation of the earth causes twilight and dawn. Twilight is the period between sunset and complete darkness where the apparent sun appears bigger and stays well after sun set. Dawn refers to the brief period between sunrise and full daylight. Dawn and twilight occur because the earth receives diffused light from the sun while it is still below the horizon. This event is short around the equator but the length increases as one moves from the equator to the poles. Since sunset and sunrise are caused by the rotation of the earth, it implies that, it associated twilight and dawn are also caused by rotation.

REVOLUTION OF THE EARTH

It is the movement of the earth around the sun. It takes 3651/4 days to complete a revolution. The

path along which the earth revolves around the sun is called the orbit. The orbit is elliptical or oval shape. Average distance between the earth and the sun is 1480800.00km. Revolving earth is inclined at an angle of 661/2

0 to the plane of the ecliptic

A DIAGRAM ON THE REVOLUTION OF THE EARTH

EFFECTS OF REVOLUTION FOR THE EARTH

1. Revolution leads to varying Length of day and night: The axis of the earth which is inclined to the plane of the ecliptic (the plane in which the earth orbits round the sun) at

an angle of 6612

, and the position of the earth in relation to the sun give rise to varying

lengths of day and night. When the sun is overhead at the tropic of cancer, places in the northern hemisphere experience longer days and shorter nights, while those in the southern hemisphere experience longer nights than days. Daylight increases as one moves pole ward. At the Arctic Circle, the sun never set at mid-summer (21st June) and there is a complete 24 hours period of continuous daylight. During winter in Northern hemisphere, as one moves northwards, hours of darkness increases. At Arctic Circle, the sun is never rises and there is darkness for the whole day around 22nd December. When it is summer in the Northern hemisphere the southern hemisphere experience winter

2. Revolution brings about changes in the altitude of Mid-day sun: In the course of the

year, the earth’s revolution round the sun with its axis inclined at 6612

to the plane of the

ecliptic changes the apparent altitude of the midday sun. The sun is vertically overhead at the equator on two days each year. These are usually 21 March and 23 September through the date changes because a year is not exactly 365 days. These two days are termed equinoxes (21 March and 23 September) which means equal nights and days because on these days, all parts of the World have equal days and nights. March 21 is called vernal equinox and September 23 is Autumn equinox. After the March equinox the sun appears

to move north and is vertically overhead at the Tropic of cancer (2312oN ) on about 21

June. This is known as the summer solstice or June solstice, when the northern hemisphere will have its longest day and shortest night.

On 22nd December, the sun will be overhead at the Tropic of Capricorn (2312

oS).

This is known as winter solstice when the southern hemisphere will have its longest day and shortest night. The tropics thus mark the limits of the overhead sun and beyond this

the sun is never overhead at any time of the year. Beyond the Arctic Circle (6612oS)

where darkness lasts for six months and daylight is continuous is remaining half of the year, it is always cold; for even during the short summer the sun is never high in the sky. Within the tropics, as the midday sun varies very little from its vertical position at noon daily, the four seasons are almost indistinguishable.

3. Revolution of the earth causes changes in seasons or brings about the four seasons in the earth. The four seasons include summer, winter, spring and autumn. Each of these lasts for three months. These four seasons are experienced in the temperate regions, only two, that is wet and dry seasons, are experienced in the tropical regions. This is because in the tropics, temperatures are high throughout the year and the difference between hot and cold conditions is not important so the seasons are based on rainfall and not temperature. Summer is the warm period; when the sun is great and temperatures are high. Summer occurs when the overhead. Sun falls on the Tropic of Cancer which is in the northern hemisphere on 21st June, when the northern hemisphere experiences summer, the southern hemisphere will be experiencing winter. From the northern hemisphere, the overhead sun falls on the equator. At this period, the northern hemisphere will now experience Autumn since the sun is less concentrated there. But at the same time, the southern hemisphere will be experiencing spring and all these happen on 23rd September.On 22nd December, the overhead sun from the equator will now fall on the tropic of Capricorn. In view of this, the southern hemisphere will be experiencing summer whereas the northern hemisphere will experience winter. On 21st March, the overhead sun from the southern hemisphere will fall on the equator again. At this period, the northern hemisphere will become warm since the beams of the sun concentrate much there. This is the period the northern experience spring. At the same time the southern hemisphere will be cooling since the beam of the sun move away gradually. The area will be experiencing Autumn which is cold period with low temperatures.

4. Revolution determines a year: The earth’s revolution helps in marking of a year. This is because the time taking by the earth to move around the sun is fixed at 3651/4 which makes up the year. Thus, revolution determines the number of days that will give us a year

THE DIFFERENCES BETWEEN ROTATION AND REVOLUTION

i. Revolution causes changes in the altitude of mid-day sun whereas Rotation causes between two meridians (i.e. 15o apart).

ii. Revolution earth is inclined at an angle of 6612

o to the ecliptic plane but the rotating

earth is inclined at an angle of 2312

o along it axis.

iii. Revolution of the earth causes the four seasons (summer, winter, Autumn and spring) whilst the rotation of the earth causes day and night.

iv. The earth revolves round the sun on its orbital plane but the earth rotation involves the spinning of the earth on its own axis.

v. The earth takes 36514

days to complete one revolution whereas the earth takes 24 hours to

complete one rotation.

SOLSTICE

Solstice means the period for day and night are not equal. It is the period when the overhead sun is vertical on either the tropics of cancer or tropic of Capricorn. It occurs mostly on 21st June and 22nd December.

TYPES OF SOLSTICE

A. Summer solstice: The summer solstice occurs on June 21st. It is caused by the inclination of axis and the revolution of the earth round the sun. At this time, the North Pole is titled towards the sun. The sun is vertically over head at the tropic of cancer. The tangent rays of the sun touches the North Pole but the sun does not cross the Antarctic Circle. The period where the overhead sun is at Tropic of cancer is called summer solstice. During the summer solstice, the northern hemisphere experience longer days and shorter nights whilst at the same period, the southern hemisphere experience shorter days and longer nights

A DIAGRAM ON SUMMER SOLSTICE

B. Wintersolstice – 22ndDecember: Winter solstice occurs on 22nd December. The inclination of the axis and revolution of the earth round the sun cause this type of solstice. On this day, the South Pole is title towards the sun. The sun is overhead at the Tropic of Capricorn at moon. The tangent rays of the sun touches the South Pole but does not cross the Arctic Circle. During the winter solstice, the Southern hemisphere experience longer days and shorter night whereas the people in the Northern hemisphere will experience shorter days and longer night.

DIAGRAM ON WINTER OR SOUTHERN SOLSTICE

EQUINOX

This refers to equal day and equal night all over the world. It occurs twice a year.

March 21st and September 23rd. It occurs when the mid-day sun is directly overhead at the

Equator.It may be in the spring or autumn. In Northern Hemisphere, spring Equinox occurs on

March 21st. In Southern Hemisphere, Spring Equinox is on September 23rd

A DIAGRAM ON EQUINOX

DIFFERENCES BETWEEN EQUINOX AND SOLSTICE

i. Equinox is either autumn or spring but solstice is either winter or summer.ii. During solstice, the sun is over head at Tropic of cancer or Tropic of Capricorn

whereas during equinox, the overhead sun is at the equator.iii. Solstice lakes place 21st June and 22nd December but Equinox takes place on 21st

March and 23rd September.iv. Places that experience solstice have longer days in summer and longer nights in

winter whilst places that experience equinox have equal days and equal nights.

ECLIPSEAstronomers define eclipse as the obscuring of one celestial body by another. This occurs when one body shuts off the light emitted from a source so that the glow cannot be seen by the other.

Types of EclipseThere are two types of eclipse. These are Eclipse of the Moon or Lunar eclipse and Eclipse of the sun or Solar eclipse.

Eclipse of the sun( Solar eclipse)This occurs when the moon comes between the sun and the earth, thereby, causing partial or total darkness of the earth. That is, if the moon blocks the sun’s rays reaching the earth so that the shadow of the moon is instead cast on the earth causing darkness on the earth.

A DIAGRAM ON SOLAR ECLIPSE

Eclipse of the Moon or Lunar eclipseThis occurs when the earth comes between the moon and the sun. Thus, if the earth cuts off the rays of the sun from reaching the moon so that the shadow of the earth instead falls on the moon causing darkness on the moon

A DIAGRAM ON LUNAR ECLIPSE

TWILIGHTThis is the period between sun set and complete darkness where the apparent sun

appears bigger and stays well after sunset. It is caused by refraction of the sun rays as it goes down the horizon. Twilight is longer at the temperate and Arctic circle than the equator because the refraction of the rays of the Sun is greater at the temperate and Arctic and Antarctic circles than equator. At this period, the sun rises and set

vertically at equator but rises and sets at angle in the Arctic and Antarctic Circles. The sky assumes orange colour and visibility is not as much as during the day but is better

than total darkness.

A DIAGRAM ON TWILIGHT

DAWN

Dawn refers to the brief period between sunrise and full day light or full brightness of day time. Dawn occurs because the earth receives diffused light from the sun whilst it is still below horizon.

DIAGRAM

LOCATION OF PLACES ON THE GLOBE

The earth’s is so big that unless a mathematical method is used,it is difficult to locate any place on it. For this reason, Imaginary lines have been drawn on the globe. One set running east and west parallel to the equator, are called lines of latitude. The other set runs north and south passing through, the poles and are called lines of longitude. The intersection of latitude and longitude pin-points any place on the earth’s surface.

LATITUDES AND LONGITUDES

LINES OF LATITUDES

Definition: Latitudes are imaginary lines running from east to west on the surface of the earth or the globe. ORThey are Angular distance of points on the earth’s surface, measured in degrees from the center of the earth north or south of the equator.

The most important lines of latitude are: the equator (Oo) the tropic of cancer (2312oN ) the tropic

of Capricorn (23o 12

oS), the Arctic Circle (6612oN ) and the Antarctic Circle (66

12oS).

A DIAGRAM SHOWING LINES OF LATITUDES

CHARACTERISITICS OF LINES OF LATITUDES

i. Equator is the only great circle among the lines of latitudesii. Latitudes are parallel to each other and the equator which lies midway between the

poles.iii. Lines of latitudes run from the west to east or east to westiv. Lines of latitudes get shorter towards the poles v. Lines of latitudes are used to calculate distancevi. Lines of latitudes are called parallelsvii. Latitudes are Imaginary lines on the earth’s surface.viii. Latitudes runs from Oo-90o North and South of the Equatorix. Distance between latitudes is 111km or 69 milesx. Latitudes are measured in degrees

USES OF THE LINES OF LATITUDESi. Latitudes are used to calculate distances between two places on the earth’s surfaceii. The intersection of latitude and longitude pin-points the location of a place on the

globe

USING LINES OF LATITUDES TO CALCULATE DISTANCEFormula to be used

i. North –North = subtractii. South – South = subtract iii. North – South = Add

iv. Equator (Oo) – North / South – Add or subtract

HINT

Every 1o of latitude is approximately 111km on the land. 111km is arrived by dividing the length of equatorial circumference which is 40, 085k by 360o since the earth turns through 360o of longitude for a day.

40,085 = 111km

360o

PROCEDURES FOR CALCULATING DISTANCE USING LATITUDES

i. Locate the two places involvedii. Find the latitude difference between the two places involvediii. Multiply the latitude difference by 111km.

EXAMPLE 1

Calculate the distance between the equator (latitude Oo) and Abuja 6oN

SOLUTION

a. Latitude of Equator is Oo

Latitude of Abuja is 6oN (using procedure i)b. The difference in Latitude Oo+6oN = 6o (using procedure ii)c. Since 1o = 111km

Therefore 111×6 = 666km (using procedure iii)

The distance between the equator and Abuja is 666km

EXAMPLE 2

Calculate the distance between the Zimbabwe on latitude 30oS and Portugal on latitude 40oN

Solution

a. Locate the places involved Latitude of Zimbabwe = 30oSLatitude of Portugal = 40oN

b. Latitude difference = 30oS+140oN = 70o

c. Since 1oC =111km = 111×70 = 7,770km

The distance between Zimbabwe and Portugal is

= 7770km

EXAMPLE 3

Calculate the distance between Accra. (4oN) and Cairo (30oN)

a. Locate the two placesLatitude of Accra = 4oNLatitude of Cairo = 30oN

b. Latitude difference = 30oN-4oN= 26o

c. Since 1o= 111kmTherefore 26o = 111×26 = 28861kmThe distance between Accra and Cairo is 2886km

CALCULATING FOR THE LATITUDE IF DISTANCE IS GIVEN

EXAMPLE 1

If the distance between Accra (4oN) and Niamey is 1, 665km,

What latitude is Niamey, assuming that Accra and Niamey are in the same hemisphere?

NB: We apply similar procedures.

SOLUTION

a. Locate the places involved latitude of Accra = 4oNLatitude of Niamey = ?

b. Difference in distance = 1665kmc. Difference in degrees = 1665

111

= 150

d. Since both towns are in the same hemisphere, we add the latitude of Accra to difference in degrees.

40 + 15o = 19oND

Therefore Niamey is on latitude 19oN.

EXAMPLE 2

Suppose the distance between Lagos (4oN) and Cairo is 2,886km. What latitude is Cairo if Lagos and Cairo are on the same latitudes?

SOLUTION

a. Locate the places involved Latitude of Lagos = 4oNLatitude of Cairo = ?

b. Differences in distance = 2886kmc. Difference in degrees = 2886

111= 26o

d. Since both cities are in the same hemisphere, we add the latitude of Lagos to the difference in degrees.

4o + 26o = 30oN

Therefore Cairo is on latitude 30oN.

EXAMPLE 3

If the distance between South African and Spain is 7770km. what will be the latitude of Spain if South Africa is on latitude 30oN (Hint South Africa and Spain are not on the same latitude).

SOLUTION

Latitude of South Africa = 30oS

Latitude of Spain = ?

Differences in distance = 7770km

Differences in degrees =7770

D

111

=70o

Since South Africa and Spain are in different hemisphere, we subtract the latitude of South Africa from the difference in degrees.

70o – 30o = 40oN

Therefore Spain is on latitude 40oN.

LINES OF LONGITUDES (MERIDIANS)

Definition: Longitudes are angular distance east or west of the Greenwich Meridian measured from the centre of the earth. ORThey are imaginary lines running on the surface of the earth from the North Pole to the South Pole. Important lines of longitudes are: longitude Oo which is called Greenwich Meridians or prime Meridian, longitude 180oE, longitude 180oW, long 100oE etc . The longitude passing through London in Britain and Tema in Ghana is called the Greenwich Meridian or prime Meridian.

DIAGRAM SHOWING LINES OF LONGITUDES

D

CHARACTERISTICS OF THE LINES OF LONGITUDES

i. Lines of longitudes are also known as Meridianii. They run from north to south on the globeiii. Lines of longitudes meet at the polesiv. They lie west or east of the prime Meridianv. They become closer near the polesvi. Two opposite lines of longitudes form a great circlevii. They have the same lengthviii. They are measured in degreesix. They have total of 360o

USES OF LONGITUDESi. Longitudes are used to calculate time in relation to the Greenwich Meridian ii. Longitudes together with latitudes are used to locate places on maps.

SIMILARITIES BETWEEN LONGITUDES AND LATITUDES

i. Both are imaginary lines on the earth’s surface.ii. Both are angular distances in degrees.iii. Both are used in locating places on mapsiv. Both contain Great circles

v. Both lines are measured in degrees from the center of the earth.vi. Both intercept one another at a point

DIFFERENCES BETWEEN LONGITUDES AND LATITUDES

i. Lines of longitudes run from north to south while lines of latitude run from east to west on the globe or the earth

ii. All opposite lines of longitudes form Great circles while the equator is the only latitude which forms a Great circle.

iii. All lines of latitudes are parallel while lines of longitudes converge at the polesiv. Lines of latitudes decrease in length from the Equator toward the pole while all lines

of longitudes are of equal length.v. Lines of latitudes increase in value from the Equator towards the pole while lines of

longitudes increase in value eastwards and Westwards of the Greenwich Meridian.vi. Lines of longitudes are used to calculate time while lines of latitudes are used to

calculate distance.vii. Lines of longitudes are called meridians while lines of latitudes are called parallels.viii. Each longitude is a semi-circle of 180o while latitude is a complete circle of 360o

CALCULATION OF LOCAL TIME

It is possible to calculate the time of places on different longitudes if the time at one of the places is known. We base our calculations on the fact that there is a difference 1 hour between places that are 15o apart.

PROCEUDRES OR STEPS FOR CALCULATING LOCAL TIME

A. Step One: Locate the places involved in the question.B. Step Two: Find the longitude difference C. Step Three: Convert the longitude difference to timeD. Step four: Adjust the time according to the direction of movement. (West or East)

\

FINDING TIME WHEN LONGITUDE IS KNOWN

Example 1

What will be the local time in country × on longitude 15oE when it is 5.00pm in country Y.

SOLUTION

STEP 1: Locate the places involved:

Country ×(15oE Country Y (45oE)

?

5.00pm

(NB)There are two lines. Country × has to come first before country Y due to the fact that, longitude increases from 6o to 180oE eastward. So, 15oE comes first before 45oE.

Step 2: Find longitude difference

From the question, both countries longitudes are in the East (that is 15oE and 45oE). In this case, we have to subtract therefore, the longitude difference is 45oE – 15oE = 30o

[HINT]

East – East = Subtract

West – West = Subtract

East – West = Add

Greenwich Meridian (Oo) West or East = Add or Subtract

Step 3: Convert the longitude difference to time

[Hint] 360o = 24 hours

15o = 1hour

1o = 4 minutes

From the question, the longitude difference is 30o. Therefore 30o should be converted to time.

Since 15o = 1 hour

30 o

15

= 2 hours

Since country Y is east of country ×, we subtract = (5 hours – 2 hours)

The time for country x is 3.00pm

EXAMPLE 2

What will be the time in Brazil on 500w when it is afternoon in London on longitude Oo

D

SOLUTION

Brazil (50oW) London (Oo)

W E

? 12.00 noon

Hint: 500w comes first before Oo because the longitude increases westward from Oo to 18oW

Longitude difference

50oW + 0o = 50o

Convert 50o to time

But 15o = 1 hour

1o= 4 minutes

3 hours

15o 50o

45o

5o

5×4minutes = 20 minutes

= 3 hours 20 minutes

Hint: After dividing the longitude difference by 15o, any remainder must be multiply four minutes. [i.e. 5o×4 minutes]

Therefore, 50o = 3 hours 20 minutes

Since the arrow is pointed to the question mark (ie West), we subtract 3 hours 20 minutes from 12.00 noon – 3 hours 20 minutes

= 8:20 am

Therefore, the local time in Brazil is 8:20 am

EXAMPLE 3

A football match between town × (18oW) and town Y (140oE) was played in town× on Saturday, the 22nd of September 1995 at 6.pm. calculate the

i. Time

ii. Day to listen to the commentary of the match

SOLUTION

STEP 1

Town × (18oW) Town Y [140E]

W

E

6pm Add ?

STEP 2

Since the countries are in East and West, we add their longitudes

18oW + 140oE = 158o

STEP 3

Convert 158o to time

But 15o = 1 hour

= 4 minutes

10 hours

15o 158

150

8o

Therefore, 8o × 4minutes = 32 minutes

Actual time = 10hours 32 minutes

STEP 4

Since the arrow is pointing to the question mark or East, we add the time.

6.00pm + 10 hours 32 minutes = 4:32 am

Since the time is now am, the next day morning, the day, date and time will be Sunday, 23/9/1995 at 4:32 am respectively.

i. Time will be 4:32 amii. Day to listen to the commentary of the match is Sunday, 23/9/1995

EXAMPLE 4

If it is 11:00am in Accra on longitude Oo, calculate the time in Cairo on longitude 30oE

SOLUTION

Longitude of Accra = Oo

Time of Accra = 11:00am

Time in Cairo = ?

Longitude of Cairo = 30oE

Longitudinal difference = 30o + Oo= 30o

15o of longitude = 1 hour

1o = 4 minutes

Time of difference between the two places

= 30 o × 1 hour /15o

15o

= 2 hours

Since Cairo is east of Accra, its time will be ahead of that of Accra.

Therefore, when it is 11:00am in Accra, the time in Cairo will be 11 hours+ 2 hours = 13 hours or 1:00pm

NB:During examination, candidates can ignore the writings of the steps and arrows used in example 1, 2 and 3 and solve the question as in example 4.

FINDING LONGITUDES WHEN TIME IS KNOWN

At times, the local times of two places are mentioned and students are required to find the longitude on which one of the towns is located. The steps below should be followed.

STEP I: Locate the places involved

STEP 2: Find the time difference

STEP 3: Covert the time difference to longitude

STEP 4: Adjust the longitude to the direction of movement (West or East)

EXAMPLE 1

What is the longitude of a town × whose time is 12.00 noon when Greenwich Mean time 6.00pm

SOLUTION

STEP 1

Town ×? Subtract Longitude (Oo)

W E

12.00 noon 6.00 pm

STEP 2: Find the time difference 12:00 noon – 6.00 pm = 6 hours

STEP 3:Convert 6 hours to longitude

Since 15o = 1 hour

Therefore, 6 hours = 6×15o = 90o

STEP 4: Since the arrow is pointing to the question mark (West), therefore the 90o is to the West which is 90oW.

Longitude of town × = 90oW

EXAMPLE 2

Find the longitude of a town M whose time is 8:00 am when the time of another town N on longitude 30oE is 2:00pm the same day.

SOLUTION

STEP 1

TOWN M? Subtract Town N (Longitude 30oE)

W E

8:00 am 2:00 pm

NOTE:Time of town M has to come first before Town N because 8:00 am comes first before 2:00pm the same time.

STEP 2: Find the time difference between 8: am and 2:00 pm

2:00 pm – 8:00 = 6 hours

STEP 3: Convert 6 hours to longitude but 15o = 1 hour

Therefore, 6 hours = 6 × 15o = 90o

STEP 4: Since the arrow is pointing to the question mark (West), we subtract

90o – 30o = 60o W

Therefore, the longitude of Town M = 60o W

Using different Approach in Solving Similar Questions

EXAMPLE 3

The time in town ‘C’ is 6:00pm while the local time in town “D” on longitude 30oW is 2:00pm. Find the longitude on which town “C” is located.

SOLUTION

Longitude of Town D = 30oW

Time of Town D = 2:00 pm

Time of Town C = 6:00 pm

Longitude of Town C =?

For every 15o of longitude, we have I hour difference.

Differences in time between Town “C” and Town “D” is the time between 6:00pm and 2:00pm = 4 hours.

Difference in longitude = 4×15 =60o

Time at Town “C” is ahead of time at Town D

Therefore Town C is the east of Town D

Therefore, longitude of Town C=600-300

= 300E

EXAMPLE 4

Two towns M and N are on different time zones. When the time in town M is 3:00pm, the time in town N is 10:00 am the same day, calculate the longitude of town N if the longitude of town M is 50oE.

SOLUTION

Longitude of Town M = 50o E

Time of Town M = 3:00pm

Time of Town N = 10:00am

Longitude of town N =?

For every 15o of longitude, we have I hour difference.

Differences in time between Town M and Town N is the 3:00pm and 10:00pm = 5 hours

Difference in longitude = 5×15

= 75o

Time at Town N is behind of time at Town M

Therefore Town N is the West of Town M

Therefore, longitude of Town N =750-500= 250W

GREAT CIRCLES

Great circles are lines or circles that divide the earth or globe into two halves.

CHARACTERISTICS OF GREAT CIRCLES

i. They are countless lines running on the globeii. They are of equal lengthiii. They can be drawn in any direction. E.g from north to south, west to east. etc.iv. Great circles are not always seen as straight lines on the maps due to the earth’s

spherical shape, they sometimes appear on maps as curves.v. All opposite longitudes are great circles Eg. Longitude Oo and longitude 180o, or

150oW and 30o E etc.vi. Equator is the only latitude which is a great circle.vii. They are the shortest distance between two points on the globe. In view of this, ships

and air craft make use of great circle routes, particularly where the shape of the water surfaces, weather and political consideration allow. For instance, aircrafts use the great circle routes between London and Anchorage.

viii. The center of the great circle is also the center of the earth

DIAGRAM OF GREAT CIRCLE DIAGRAM OF GREAT CIRCLE ROUTE

SMALL CIRCLE A circle is any line that does not divide the earth into two equal halves or hemisphere.The center of the small circle is not the center of the earth. All lines of latitude except the equator are small circles. Examples are tropic of cancer (231/2

0 N),Tropic of Capricorn(231/2

0N), Arctic cicle (661/20N) and Antarctic cicle(661

/20S)

INTERNATIONAL DATE LINE

The international Date Line ( IDL) is an imaginary line on the surface of the Earth from the north to the south pole and demarcates one calendar day from the next

Characteristic of International Date Line

i. International Date Line is where the date changes by exactly one day or 24 hours when it is crossed.

ii. It is an imaginary lineiii. It runs rough on the 180o Meridian iv. It is a longitude which marks the difference in date or datev. Once one crosses the International Date Line to the right (east), one gain a day ahead.vi. Once one crosses the International Date Line to the left (West), one losses a dayvii. The International Date Line joins the Greenwich Meridian to form a Great circleviii. It does not follow longitude 180o rigidly.ix. It is Zigzag to avoid cutting some countries or islands into two and also enable

different countries have the same time.

DIAGRAM ON INTERNATIONAL DATE LINE

GREENWICH MEAN TIME (GMT)

This refers to the time at Greenwich Meridian or longitude. It is also known as the World time. Countries in the World adjust their time from the GMT. Cities on Greenwich Meridian that observe GMT are London in Britain and Accra in Ghana.

WORLD TIME ZONES

Refer to the grouping in places on the surface of the earth into time groupings based on

longitudes.

Characteristic of World Time Zones

i. Countries within the same longitudinal stretch are placed in the same time zone.ii. Usually all places within a country adopt a uniform time zone.

iii. Countries with large longitudinal stretch. E.g. Russia and U.S.A have many time zones.iv. The world’s divided into 24 hour time zonesv. Each time zone has a span of 15o of longitude

vi. Time west and time east are separated by International Date Line (IDL).vii. The time of places in the east is ahead of places in the West

viii. Longitude Oo (Greenwich Meridian) is the reference point for all time zones.

STANDARD TIME OR LOCAL TIMEi. Local time refers to the time in a given localityii. Local times of places in a country varyiii. For every 1o longitudinal difference, there is a variation in time by 4 (four) minutesiv. The local time of places in the east is ahead of the local time of places in the West.

SOLVE PAST QUSTIONS

1(a). Explain the following terms:

i. Rotation of the earth;ii. Revolution of the earth;

iii. Equinox

b. Outline three effects of the revolution of the earth [May/ June 2015]

2. (a). What is a latitude? [May/ June 2014]

(b). State any three similarities between lines of longitudes and of latitudes

(c). Outline any five ways in which lines of longitudes differ from lines of latitude

3 (a). Write explanatory notes on any two of the following:

i. Time zones;ii. Local time

iii. International Date Line.

b. Two towns A and B are on different time zones. If the time in town A is 9.00am.when the time in town B is 6.00 pm the same day, calculate the longitude of town B if the longitude of town A is 300W [ Nov./ Dec. 2014]

4 (a). Explain the terms [ May/ June 2007]

i. Latitudesii. Longitudes

(b). Calculate the distance between town X on latitude 300S and town Y on latitude 400N.

5(a). Draw an outline of the earth and show any three of the following:

i. Equatorii. Tropic of Cancer

iii. Tropic of Capricorniv. Artic Circlev. Antarctic Circle

(b). Describe three characteristics of the lines of Latitude

(c).An international football match between Nigeria and Sierra Leone is scheduled for 4:45pm local time Saturday in Port Harcourt, Nigeria (longitude 70E). Calculate the local time that football fans in Freetown, Sierra Leone (longitude 130W) can tune in radio set for the match commentary. [ May/ June 2008]

6(a). Highlight any two similarities and three differences between lines of longitudes and lines of latitudes

b).A table tennis match is being played in Ghana 0 0 Meridian at 6.00hrs. If the commentary of the match is relayed over the local radio station in Rio de Janeiro (longitude 450W) at what time will the people of Rio de Janeiro tune in their radios for the commentary.[ May/ June 2009]

7(a).Describe any three effects of earth’s revolution

(b). Using appropriate diagrams, write notes on any two of the following:

i. Twilightii. Solstice

iii. Equinox [ Nov/ Dec. 2009]

8(a). Name two types of Earth’s movement

(b).Highlight four effects of effects of any one of the Earth’s movement in (a) above

(C). When its is 12.00noon local time on Friday at Cairo Longitude 30 0E. What will be the local time in New York 750E? [May/ June 2011]

9(a). What are longitudes?

(b). Outline three characteristics of lines of longitudes

(c) Calculate the distance between P on latitude 23 0N and town Q on latitude 350S both lying on the same longitude [ Nov./ Dec. 2011]

(10a). What are latitudes?

b.State any four characteristics of latitudes

c. Highlight any three similarities between longitudes and latitudes [ Nov./ Dec. 2013]

THE STRUCTURE OF THE EARTH

It is quite impossible to know exactly how the earth was formed about 4500 million years ago, but from the evidence of volcanic eruptions, earthquake waves, deep-mine operations and crustal borings, the following facts are quite clear.The earth is made up of sSTRUCeveral concentric layers. The outer layer is the earth crust. Immediately beneath the crust is the mantle. The interior layer is the core. Hydrosphere is the liquid portion of the earth which comprises the seas, oceans and other water bodies. The atmosphere which is also part of the earth is the blanket of gases surrounding the earth. It is the gaseous part of the earth.

DIAGRAM ON THE STRUCTURE OF THE EARTH

A. THE CRUST (LITHOSPHERE)

It is the outermost layer or zone of the earth

CHARACTERISTICS OF THE LITHOSPHERE

i. It is the solid portion of the earth

ii. It is made up of rocks and minerals

iii. It has the upper layer and the lower layer

iv. The upper layer is made of granitic rocks and forms the continent

v. It contains silica and alumina and so it is called sial

vi. It has a density of 2.7

vii. The lower layer forms the ocean floors

viii. It is made up of denser basaltic rocks

ix. The density of the lower layer is 3.0

xi. The crust contains mainly silica, iron and magnesia

xii. Hence it is called sima

INTERACTION WITHIN THE LITHOSPHERE

i. The rocks change to minerals like gold, diamond, petroleum etc.

ii. Rocks weather to form the soil

IMPORTANCE OF THE LITHOSPHERE TO MAN

i. Lithosphere forms the basis of all human settlements

ii. Most human activities like farming, mining, trading etc. are carried out on the lithosphere

iii. Mineral resources are derived from the lithosphere

iv. It aided transportation through construction of roads, railway, airport etc.

v. It supports human life since all human activities take place on it

B. HYDROSPHERE

It is the liquid portion of the earth

CHARACTERISTICS

i. It occupies 70% of the earth surface

ii. It includes the rivers, lakes, streams, oceans, icebergs etc.

iii. It is the habitat of acquatic organisms like fish, crabs, crocodiles, etc.

iv. It is the component of the biosphere

v. The water of the hydrosphere surrounds the land masses of the earth

vi. Ocean water accounts for 97% of the hydrosphere

vii. It also includes underground water

INTERACTION WITHIN THE HYDROSPHERE

i. Water from seas and oceans evaporate to form clouds which eventually fall as rain (Hydrological cycle)

ii. Water from rivers, streams and rainfall together form the seas and oceans

IMPORTANCE OF HYDROSPHERE TO MAN

i. Hydrosphere provides water for both domestic and industrial activities

ii. Rivers are dammed to generate hydro-electric power eg. Volta River

iii. Rivers, streams, oceans provide precious minerals like gold, diamond, petroleum, salt etc.

iv. It provides employment opportunities for people eg. Fishermen, fishmongers, canoe builders

v. Oceans, rivers promote sporting activities like swimming, yatching, boating etc.

vi. It is used in agriculture since channels are constructed to have access to water to irrigate farms

vii. It provides a medium of transportation as oceans, rivers, lakes provide waterways for vessels, boats and canoes to carry people and goods from one place to another

viii. Hydrosphere promotes tourism eg. Beaches, rivers etc are sites for recreation.

ix. It provides food in the form of fish to mankind

C. THE ATMOSPHERE

It refers to the blanket of gases surrounding the earth. When one extends skywards for over 24 kilometres, the earth is enveloped by a mass of gases which make up the atmosphere.

CHARACTERISTICS OF THE ATMOSPHERE

i. It is the gaseous part of the earth

ii. It is a layer of gases surrounding the earth

iii. Its density decreases progressively with elevation

iv. All weather activities take place in the atmosphere

v. It contains water vapour in lower layers

vi. It contains 78% nitrogen, 21% oxygen, 0.03% carbon dioxide and 0.97% rare gases

INTERACTION WITHIN THE ATMOSPHERE

i. Plants take in carbon dioxide and give out oxygen

ii. Animals take in oxygen and release carbon dioxide for plants

iii. Water vapour combines with nuclei substances to form clouds and rain

IMPORTANCE OF ATMOSPHERE TO MAN

i. Atmosphere provides oxygen for animals

ii. It is the habitat of certain living things like birds.

iii. It provides carbon dioxide to enhance photosynthesis

iv. It contains the ozone layer which reduces the burning effect of ultra-violet rays of the sun

v. It provides nitrogen for plants growth

vi. Atmosphere is a medium of communication and transportation

D. BIOSPHERE

It is the zone of the earth occupied by living things such as plants, animals and mankind. OR It is the interface between the lithosphere, the hydrosphere and the atmosphere which create a conduciveenvironment for living organisms to live. The great equatorial forest, the temperate forest , the tropical and temperate grasslands, with their countless swarms of animals and insects, as well as tangles of sea weed, coral reefs and shoals of fishes are part of the sphere of life (biosphere). It is a circular belt round the earth hence the use of the word “sphere”

CHARACTERISTICS OF BIOSPHERE

i. It is a layer of the earth on which life exists

ii. Biosphere is a narrow zone of complex biological and chemical activities

iii. It derives its energy from the sun

iv.Biosphere has maximum thickness only a few kilometers

v. It includes organisms like plants, animals and micro organisms

vi. It includes the lower atmosphere, upper lithosphere and the hydrosphere

IMPORTANCE OF BIOSPHERE TO MAN

i. The biosphere supports the life of plants and animals. Thus, biosphere provides the ingredients necessary for plants and animal’s lives. Eg. Sunlight, water, oxygen, carbon dioxide

ii. It is the habitat of plants, animals and micro-organisms. Biosphere provides a natural home for plants, animals and micro-organism. eg. Plants and animals live in the upper lithosphere, oceans, rivers etc.

iii. It balances the atmosphere. That is, the activities of plants and animals in the biosphere ensure equal quantities of gases. Eg. Plants take in carbon dioxide from animals and send out oxygen which is used by animals.

iv. It purifies the atmosphere. Through rainfall, certain particles such as dust, smoke are cleared from the atmosphere

v. Plants and animals provide employment to man. Job opportunities like fishing, hunting and lumbering are created for fishermen, hunters and timber contractors, chainsaw operators respectively

vi. It provides medicine: Bark, roots and leaves of trees and shrubs are used to prepare medicine for man.

vii. It provides food: Biosphere provides fertile soil and other conditions necessary for the growing of crops to feed mankind.

viii. It provides raw materials to feed industries. Raw materials like timber, hides, skin, meat are provided for industries for further production of goods.

ix. Serves as tourist attraction: The wild life and how certain forest look like present such beautiful scenery that tourists are attracted to visit them. Eg.Wildlife in East Africa, the big tree in Ghana.

INTERACTION WITHIN THE BIOSPHERE

i. Animals decompose to provide manure for plant growth

ii. Animals depend on plants for their food

iii. Micro-organisms in the soil aerate the soil to promote plant growth

iv. Animals provide carbon dioxide for plants for respiration

v. Plants provide oxygen for animals during photosynthesis…..

PROBLEMS ASSOCIATED WITH INTERACTION OF LIVING ORGANISM IN THE BIOSPHERE

i. The activities of man creates imbalances and disturbances in the ecosystem. Eg. The activities of man causes global warming, acid rain and their associated effects on the environment

ii The interaction of organisms leads to extinction of certain animal species. Many common animal species in the forest are getting extinct due to the excessive exploitation of the forest resource

iii The interaction of the living organism leads to the pollution of the environment. The activities of living organisms such as bush burning, exhaust fumes, improper disposal of industrial and domestic waste, oil spillage etc. causes environmental pollution

iv.It leads to deforestation. This is the cutting down of trees without replacement

v The interaction results in depletion of forest resources. This is where both the living and non living things in the forest are depleted

THE CORE (BARYSPHERE)

It is the inner most part of the earth

Characteristics Of The Core

i. The density of the core is about 10gms/cum or m3 the thickness is about 3500km in radius

ii. The temperature is between 2000oC to 3500op

iii. The inner core is solid but outer core is molten

iv. It contains nickle and iron collectively called Nife

v. It is the innermost part of the earth and consists of inner core and outer core

THE MANTLE (MESOSPHERE)

It is the part of the earth which is located immediately beneath the lithosphere

Characteristics Of Mantle

i. The middle zone in the internal structure of the earth

ii. It is found immediately below the earth’s crust

iii. It is made up mainly of dense rocks rich in olivine

iv. It is about 2900km (1800 miles) thick

v. It envelopes the core

vi. Mantle is also called mesosphere

vii. Mantle has a density ranging from 3.0 to 3.3

viii. It is plastic and in semi-liquid form

ix. Temperature ranges 500-4000oC

x. The line separating the mantle and the core is the Guttenberg discontinuity and the line separating it from the crust is the Mohorovic discontinuity.

SOLVE PAST QUESTIONS1) Draw a labeled diagram to show the internal structure of the earth

b). Outline three characteristics of each of the following:

i. the hydrosphere;ii. the mantel [May/ June 2012]2(a). Outline three characteristics of the following:i. Coreii. Mantel

b). Highlight two ways in which the lithosphere is of importance to man[Nov./Dec.2008]

3(a). Draw a labeled diagram of the structure of the earth

(b). Outline four characteristics of the biosphere

(c) Highlight three ways in which the biosphere is of importance to man [Nov./ Dec. 2006]

4a. What is the biosphere?

b. Describe any three characteristics of the biosphere

c. Highlight any four ways in which the biosphere is important

5(a) Draw a diagram of the internal structure of the earth and show the following:

(i). the lithosphere;

(ii) the core; [Nov,/ Dec 2015]

(iv) the mantle

(b) Outline three characteristics of the lithosphere

(c) In which three ways is the hydrosphere important to mankind ?