THE EARTH AND OTHER PLANETS THE SOLAR SYSTEM

WEEK 3                                                                        DATE…………………

SUBJECT: GEOGRAPHY

CLASS: SS 1   

TOPIC: THE EARTH AND OTHER PLANETS

CONTENT:

1. Components of the Solar system
2. The Earth- Size, Shape and Position in relation to the Sun and other planets

SUB-TOPIC

1: Components of the Solar system

The Solar System

The solar system consists of the sun and the nine planets with their satellites. The sun is at the centre of the planets and all other planets revolve around it on elliptical orbits. The nine planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto

The path followed by each of these planets around the sun is called ORBIT. A smaller body which moves around a planet is called SATELLITE.

The Solar System

The planets themselves can be grouped into two:

1. TERRESTRIAL PLANETS: They are Mercury, Venus, Earth and Mars. They are called Terrestrial planets because they have similar components with those of the earth being made of rock and heavy minerals like iron. They are also called inner planets because they are near the sun than others.
2. JOVIAN PLANETS: They include Jupiter, Saturn, Uranus, Neptune and Pluto. They are called Jovian planets because they have similar features with Jupiter being large and made of gaseous materials.

THE SUN

The sun is the largest star in the solar system. It is at the centre of the planets. It is stationary while all the planets move around it. It has a surface temperature of about 6,0000c with an interior temperature of over 20,000,0000c. In size, the sun is about 300,000 times as big as the earth. It is the ultimate source of light and energy to all the planets. The sun is important to man because it produces light which can be conserved as heat energy or radiant energy. Therefore, without solar radiation from the sun called insolation, all forms of life on earth surface would not have been possible. The stars which appear singly when viewed from the earth actually exist in groups or clusters which are better referred to as galaxies or nebula. The Asteroid zone or belt is a circumstellar disc in the solar system that is located roughly between the orbit of the planets mars and Jupiter. It is occupied with irregular shaped bodies called asteroid or minor planets. 

THE NINE PLANETS AND THEIR CHARACTERISTICS

MERCURY

1. It is the smallest and closet planet to the sun.
2. It is about 57,900,000km (36million miles) away from the sun.
3. It has the shortest orbit.
4. A year in mercury is only 88 days.
5. It has no satellite.
6. It has a diameter of 4880km (3030miles).
7. Mercury is the densest planet.
8. Its day is two Mercury years long.
9. The surface temperature on mercury can reach 430c. At night it can plunge to -180c

VENUS

1. It is the second closest planet to the sun.
2. It is often considered as earth’s twin because of the close proximity in size, mass (weight) and density but contains no living things.
3. It takes 225 days to complete it revolution round the sun.
4. It has no satellite.
5. It distance from the sun is about 107,200,000km.
6. It distance from the sun is about 107,200,000km. (66million miles)
7. A day on Venus is longer than a year. It completes one rotation in 243 earth days but it takes 224.7 earth days to go around the sun.
8. The surface temperature is very high, about 480c.

EARTH

1. It is the only planet which supports the existence of plants and animals.
2. It has one natural satellite called the moon, which revolve around the earth eastward once in every 27/28days.
3. It is described by the spacemen as a “beautiful jewel” when seen from space.
4. It takes the earth about 365 ¼ days to complete it orbit.
5. It is about 148,800,000km away from the sun.
6. The distance of the moon from the earth is 384,629km.

MARS

1. Mars is the fourth and next planet to the earth.
2. It has dark patches on its surface and is believed to be the next planet after earth to have possibility of some plant life.
3. It distance from the sun is 227,200,000km.
4. It takes Mars 687days to complete its orbit.
5. It has two satellite.

JUPITER

1. It is the largest planet in the solar system.
2. It contains hydrogen and methane gases with light and dark bands on its surface.
3. It has twelve satellites that circle around it.
4. Its distance from the sun is 772,800,000km.
5. It takes Jupiter 9years to complete its orbits.

SATURN

1. It is the second largest planet after Jupiter.
2. It takes about 29 ½ years to complete its orbit.
3. The distance of Saturn from the sun is about 1,417,600,000km.
4. Saturn has three rings and ten satellite.

URANUS

1. Uranus is 50 times larger than the earth and 15time as heavy.
2. Its orbits around the sun is in clockwise direction from east to west.
3. It has five satellite revolving around it.
4. It distance from the sun is 2,854,400,000km.
5. It takes about 84years to complete its orbits.

NEPTUNE

1. It is very cold, with two satellite.
2. It takes Neptune about 164.8years to complete its orbit.
3. Its distance from the sun is 4,468,800,000km.
4. It has two satellites.

PLUTO

1. This is the ninth and the farthest planet to the sun.
2. It was discovered in 1930 by Astronomer Clyde W. Tombaugh.
3. It is the coldest. It is smaller than the earth.
4. It has the longest orbit around the sun. It takes 247.7years to complete its orbit.
5. It distance from the sun is about 5,850,000,000km.

1. What is the closest planet to the sun?

A. Earth

B. Mercury

C. Venus

D. Saturn

2. What is the largest planet in the solar system?

A. Earth

B. Jupiter

C. Saturn

D. Neptune

3. What is the fourth planet from the sun?

A. Mars

B. Earth

C. Jupiter

D. Saturn

4. What planet has two satellites?

A. Mars

B. Jupiter

C. Uranus

D. Neptune

5. What planet is often considered the “Jewel of the Solar System”?

A. Earth

B. Mars

C. Venus

D. Jupiter

6. What is the diameter of the earth?

A. 12,700km

B. 10,000km

C. 15,000km

D. 20,000km

7. What is the average surface temperature of Venus?

A. -23 degrees Celsius

B. 0 degrees Celsius

C. 482 degrees Celsius

D. 737 degrees Celsius

8. How long does it take for Neptune to complete one orbit around the sun?

A. 3 years

B. 30 years

C. 164.8 years

D. 247.7 years

9. What is the ninth planet from the sun?

A. Earth

B. Neptune

C. Pluto

D. Saturn

10. What is the coldest planet in the solar system?

A. Earth

B. Jupiter

C. Pluto

D. Neptune

(Marking Guide) (answers)

1. B. Mercury

2. B. Jupiter

3. A. Mars

4. D. Neptune

5. A. Earth

6. A. 12,700km

7. C. 482 degrees Celsius

8. C. 164 years

9 C . Pluto

10. C. Pluto

IN SUMMARY

    However, the researchers said that Pluto failed to dominate its orbit around the Sun in the same way as the other planets. Therefore, it will be referred to as a “dwarf planet” and that Solar system now will be described with just eight major planetary bodies.

The Picture of how the Planets Revolve Round the Sun

EVALUATION:

1. What is Solar system?
2. List nine planets in the Solar system.
3. Describe Satellite and the Sun.
4. Mention four characteristics each of the nine planets.
5. What can you say about Pluto in recent time?

SUB-TOPIC 2: The Earth- Size, Shape and Position in relation to the Sun and other planets

The Size of the Earth

The earth is the fifth largest planet in the solar system. The surface area of the earth is approximately 443 million square kilometre (197 million square miles). Other important dimensions of the earth are:

1. Equatorial circumference     =    40,084km
2. Equatorial diameter        =    12,761km
3. Polar circumference        =    39,951km
4. Polar diameter            =    12,719km

The Shape of the Earth

The earth was thought to be flat but it is not. It has a spherical shape. It is slightly flattened at the poles to give a nearly spherical shape, hence, the earth’s shape is better described as a geoid which means, the earth’s shape.

The Sphericity of the Earth

EVIDENCE/PROOFS TO SHOW THAT EARTH IS SPHERICAL

1. CIRCUMNAVIGATION OF THE EARTH: This proves that no traveller going round the world by land or by sea has ever encountered an abrupt edge, over which he would fall. This was established and proved beyond doubt by Ferdinand Magellan and his crew who travelled round the world between 1519 and 1522.

Circumnavigation of the Earth

1. SUNRISE AND SUNSET: As the earth rotates from west to east, the places in the east experience the sun earlier than places in the west. If the earth is flat, the whole earth would experience sunrise and sunset at the same time.

Sunrise and Sunset

1. THE CIRCULAR HORIZON: When one views a distant horizon from the deck of a ship at sea, or from a cliff on land, the shape is always circular. As one climbs higher, the circular horizon widens. This type of feature is seen only on a spherical body.

1. SHIP’S VISIBILITY: When a ship is seen at a far distance, the top of the mast is seen first before the hull and later the rest of the ship’s body. In the same way, if a ship leaves a harbour it disappears gradually. If the earth is flat, the ship from a distant view would appear and disappear at once.

Ship’s Visibility on the Sea

1. PLANETARY BODIES: All other planetary bodies such as moon, stars, sun etc are circular in shape. So the earth cannot be an exception.

1. DRIVING POLES OF EQUAL LENGTH ON A LEVEL GROUND: When poles of equal length were driven at the same depth in a level ground by surveyors, it was found that the centre pole is projected slightly above the poles at either side because of the curvature of the earth. If the earth is flat, all the poles would have the same height.

Driving poles of equal length on a levelled ground

1. THE LUNAR ECLIPSE: During the lunar eclipse, the shadow of earth casts on the moon is always circular in shape. Only a sphere, like the earth can cast such as circular shadow.

An Eclipse of the Moon

1. AERIAL PHOTOGRAPH: Pictures of the earth taken from high altitudes by rockets clearly show the curve edge of the earth. This is the most recent and up-to-date proof of the earth’s sphericity.

EVALUATION:

1. Outline four proofs of the earth’s sphericity.
2. With the aid of diagrams describe three of the proofs mentioned above. 

GENERAL EVALUATION:

1. (a) Describe the planet earth. 

(b) Discuss the importance of the Sun in the Solar system.

2.   (a) Explain the solar system.

              (b) Outline four characteristics of the following planets (i) Mercury (ii) Jupiter.

3.   Explain why Pluto is referred to as ‘dwarf planet’.
4.   Differentiate between Pluto and Mercury
5.   Highlight four characteristics of Uranus.

 WEEKEND ASSIGNMENT:

Objective Test: Choose the correct answer from letter a-d

1. The fourth planet from the sun in the solar system is (A) Mercury (B) Uranus (C) Neptune (D) Mars.
2. The smallest planet in the solar system is (A) Jupiter (B) Mars (C) Mercury (D) Earth.
3. The biggest member of the solar system is (A) Mars (B) the moon (C) the sun (D) Neptune.
4. Which of the following is not a proof that the earth is spherical? (A) The circular horizon    (B) Planetary bodies as observed from telescope (C) The earth’s shadow in the moon during an eclipse (D)The four seasons (E) Sunrise and  sunset.
5. Stars tend to form clusters known as (A) satellites (B) Andromeda spiral (C) planets                      (D) galaxies
6. The North Star is (A) the brightest star in the sky (B) a satellite of earth (C) found in the constellation of Orion (D) Polaris.
7. The Sun is what type of star? (A) Blue-white dwarf (B) Red giant (C) Yellow dwarf (D) White dwarf.
8. The stars appear to move from east to west because (A) they are revolved by the earth on its axis from west to east. (B) they are actually moving from east to west. (C) of the earth’s revolution around the sun from west to east. (D) of an optical illusion.
9. The group of stars which appear to form a particular pattern is known as a (A) stellar system (B) solar system (C) constellation (D) galaxy.
10. The solar eclipse occurs when the (A) moon is between the earth and the sun. (B) moon is between the sun and the earth. (C) sun is between the earth and the moon. (D) sun is between the moon and the earth
11. The time taken by the earth to complete one revolution around the sun is known as a(n) (A) earth’s day (B) earth’s year (C) lunar day (D) lunar year.
12. The half of the earth facing the sun has (A) day (B) night (C) twilight (D) dawn
13. The curve of the horizon as seen from a ship is an indication that the earth is (A) a globe (B) pear-shaped (C) flat (D) crescent-shaped.
14. The Moon takes about ________ to complete one orbit around the Earth. (A) 27 days (B) 29.5 days (C) 30 days (D) 365 days
15. The Moon does not have any ________ of its own. (A) oceans (B) atmosphere (C) mountains (D) craters
16. The dark patches on the surface of the moon are called ________. (A) maria (B) regolith (C) craters (D) highlands
17. The Moon’s orbit around Earth is not ________. (A) circular (B) elliptical (C) geostationary (D) polar
18. The side of the Moon that always faces Earth is called the ________. (A) dark side (B) far side (C) near side (D) bright side
19. The Moon is believed to have been formed ________. (A) from a collision between Earth and another planet-sized object (B) from the debris left over after the formation of the Solar System (C) when the Sun’s gravity pulled a nearby cloud of dust and gas into orbit around Earth (D) as a result of an explosion on Earth
20. The first person to walk on the Moon was ________. (A) Neil Armstrong (B) Buzz Aldrin (C) Alan Shepard (D) all of the above.

Essay Questions:

1. (a) What is eclipse of the moon? (b) What is eclipse of the sun?