Our solar system consists of a star of average size and luminosity we call the Sun, the planets (in order of their distance from the Sun) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Kuiper Belt objects (e.g., dwarf planets like Pluto), the satellites or moons of the planets, numerous comets, asteroids, meteoroids and the interplanetary medium.
The Concept the Solar System
The Solar System is defined as the arrangement of the planets and solid objects in the Space in relation to the position from the Sun.
The System is made up of the Sun, Planets, Asteroids, Meteors, Comets and inter-planetary dust and gases. All the planets and the other bodies revolve around the Sun.
The Sun is the central body of the Solar System. All those bodies in Space are held in their positions by the gravitational force of the Sun. The bodies that revolve around the Sun are kept in their elliptical orbits by the Sun's powerful force of gravity.
For your memory: My(Mercury) Very(Venus) Easy(Earth) Method(Mars) Just(Jupiter) Speeds(Saturn) Up(Uranus) Naming(Neptune)
Components of the Solar System
- The Sun
- Planets
- Comets
- Asteroids
- Meteors and
- Satellites.
Describe the importance of the components of Solar System
- They produce heat and light potential for living organisms for example the Sun.
- They provide habitat for human and other living organisms for example the Earth.
- They form craters which later become attractive sites for tourism activities for example meteors which produce meteorites that fall on the earth surface and form craters.
The Sun
The Sun is a star.
State the dimension of the Sun relative to other Space Bodies
- Dimension of the Sun relative to other Space Bodies
- Its diameter is 1.4 Million Kilometres.
Describe the characteristics of the Sun
The Sun is composed of approximately 75% Hydrogen, 23% Helium and 3% other elements. Therefore elements which make up the Earth comprise only a small fraction of the materials which form the Sun. These include Carbon, Iron, Oxygen, Silicon etc
The Sun is the only source of light and heat that the planet receives. PThe temperature of the Sun is estimated to be 20,000,000 degrees Centigrade.
Solar Energy
Solar energy is the heat and light produced from the Sun. The Sun is the source of all energy on the Earth.
Suggest different uses of Solar Energy
- Drying clothes, meat, fish, fruits and grains.
- Used by growing plants to manufacture their own food through a process called photosynthesis.
- Generation of electricity.
- Formation of coal, gas and oil.
- Formation of clouds and rainfall through evaporation of water caused by the heat of the Sun.
- Giving power to small radios and running small telephone systems by using silicon solar battery.
- Source of Vitamin D to human bodies as the bodies absorb the Sunlight.
- For domestic purposes like cooking food, heating water etc.
Explain how the use of Solar Energy promotes Environmental Conservation
Utilization of Solar energy in manufacturing industries reduces the production of Chlorine from industrially produced chloro-floro-carbon gases which cause depletion of ozone layer. The depletion of the ozone layer causes global warming.
It is used as an alternative source of energy thus reduces depletion of forests for charcoal and firewood.
The Planets
Locate the Planets in the Solar System
Planets are bodies that revolve around the Sun. Previously they included Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Now, Pluto does not qualify to be among the planets because it is the smallest and does not revolve around the Sun. PThere are now officially only eight planets in our Solar System.
The word 'Planet' originates from the Greek word 'Planetai' which means ‘Wandering' as the planets seemed to be moving about in the Sky as ‘Wandering Stars'.
All planets revolve around the Sun in the same direction in orbits that are elliptical and nearly in the same plane. The time taken to complete an orbit depends on the distance from the Sun.
Other bodies in the Solar System
Characteristics of Comets, Asteroids, Meteors and Satellites
Comets are objects with leading heads and bright tails in the Sky. Sometimes they can be seen at night. They are composed of ice crystals and fragments of solid matter. They have highly elongated orbits around the Sun. They can be seen from the Earth only when they come close to the Sun.
Asteroids are solid heavenly bodies revolving around the Sun. They are mostly found between the orbits of Mars and Jupiter. They are in thousands and the largest has the diameter of just less than 800 Kilometres. The bodies can only be seen with a telescope because they are very far away.
Meteors are pieces of hard matter falling from outer Space. They can be seen when they come close to the earth between 110-145 Kilometres whereas as a result of friction with the atmosphere, they become hot and usually disintegrated. They fall on the Earth's surface as large boulders known as meteorites or a meteor if it is one. These bodies are made of Nickel, Iron and Silica.
Satellites are the moons of the Planets and they can be defined as the small bodies which rotate on their axis and revolve around the Sun. There are only seven (7) planets which have satellites apart from 57 satellites in the Solar System. The number of satellites depends on the size and nature of the planet.
Local incidents linked to Meteorites
There are two known meteorites in Tanzania. One is found in Mbozi district in Mbeya region and the other is at Malampaka in Kwimba district in Mwanza region.
These falling meteorites have resulted in the formation of crater or large holes.
The earth
The earth is the only Planet among thelanets in the Solar System that is known to support life. (Pluto does not qualify any longer to be among the planets because it is the smallest and does not revolve around the sun). The earth is made up of the atmosphere (air), hydrosphere (water bodies), the solid crust, molten materials and the biosphere (living organism). Water bodies cover about three quarters of the earth's surface.
The Moon
The moon is a natural satellite of the earth. It has a solid spherical body with a diameter of 3456 kilometers. The distance from the earth to the moon is 384, 403 kilometers. The moon takes 29 ½ days to make a complete revolution around the earth. The moon appears to rise in the East and set in the West because the earth spins from West to East.
ECLIPSES
An eclipse can be defined as at the total or vertical cutting off of light received by one celestial or space body from another by interception of third space body in passing between the other two.
There are two types of Eclipses:
i. The Lunar eclipse
ii. The Solar eclipse
The Lunar Eclipse
This is also known as the eclipse of the moon. It occurs when the earth passes between the moon and the sun thus casting its shadow on the moon.
The Solar Eclipse
This is also known as the eclipse of the sun. It occurs when the moon passes between the earth and the sun, thus casting its shadow over the earth.
Describe the shape of the Earth and its evidence
The shape of the Earth and its evidence
The shape of the Earth is described as spherical but it is not a perfect sphere, it is a flattened sphere. The diameter through the poles is 12,713 kilometers while at the equator it is 12,757 kilometers.
Evidence of the Earth's shape.
Sunrise and Sunset:
The earth rotates from West to East, which means that places in the East see the sun before places in the West. If the earth was flat, all places would see the sun at the same time, that is, all places would have sunrise and sunset at the same time.
Circumnavigation of the Earth:
If travelling from a certain point of the earth, you will come to the point of origin. The first traveler around the world named Magellan in 1519-1522 proved this. Magellan did not encounter abrupt edge over which he would fall in his voyage.
A Ship's Visibility:
This shows two ships but you can see that the observer is able to see only one of them. If the earth was flat, a person would be able to other ships in a sea voyage when a ship is ahead of the person.
Aerial Photographs
Photographs taken by satellites at a great distance from the earth all show that the earth's surface is curved.
Lunar Eclipse
When there is an eclipse of the moon, the shadow of the earth which is thrown on the moon is always round. Only a sphere can cast a shadow which is always circular.
Earth's Movement
Describe the types of Earth's movements
Types of Earth's movements
The Earth is in motion all the time. People cannot feel this motion because they move with it like all other planets.
There are two types of movements of the earth namely:-
i. The rotation of the Earth on its axis.
ii. The revolution of the Earth around the Sun
Describe the term rotation
The term rotation
Rotation means spinning of a body on its axis. The earth rotates or spins on its axis in an anti-clockwise direction, from West to East through 3600 in 24 hours. Thus for every 15 degrees of rotation, the earth take one hour which is the same as four minutes for every 1 degree.
An axis an imaginary line joining the N and S poles (North and South) through the center of the Earth.
Note: The rotation of the earth is very rapid although it is difficult to feel the motion. At the equator every point of the earth's surface is travelling Eastwards at about 1600 Km per hour. At latitude 40 degrees the speed is about 1280 Km per hr.
Give evidence to prove that the Earth rotates
Evidence to prove that the Earth rotates
i. During the night, stars appear to move across the sky from West to East.
ii. If one travels in a fast moving vehicle, will notice threes and other objects on both sides of the road moving fast in the opposite direction.
iii. Rising of the sun over the Eastern horizon in the morning. This shows that the point of the observation, that is the south, is moving by rotation from West to East.
iv. Day and Night. During the earth's rotations some regions face the sun while others do not face it. Those regions facing the sun experience day time whereas the regions which are not facing the sun are in darkness (night). This proves that the earth is rotating.
Explain the Significances of Earth's rotation
Significances of Earth's rotation
i. Alternation of day and Night. Rotation of the earth causes the sides of the earth which face the sun to experience daylight which is the day, whereas the side that is not facing the sun at that time will be in darkness (night).
ii. The occurrence of tides in the ocean caused by gravitational forces of the moon and sun upon the rotation of the Earth.
iii. Deflection of winds and ocean current.
iv. Time difference between longitudes: PThe rotation of the earth is responsible for difference in time between difference places on the earth. It cause the difference of one hour in every 15 degree interval between longitudes. The earth rotates from West to East and takes 24 hours to complete one rotation. The difference in time is 4 minutes for each degree of longitude.
Define the term Revolution
The term Revolution
Revolution is defined as the movement of one body round another. The earth revolves around the sun in an elliptical orbit. Due to the elliptical shape of the earth orbit the sun is closer to the earth at one point of the year than at another.
The farthest (maximum distance) position from the sun in orbit of the earth is called aphelion while the nearest position of the earth to the Sun is known as perihelion.
The Earth is at aphelion each year on 4th July, when it is at the maximum distance of 152 million kilometer form the sun. The earth is at perihelion each year on 3rd January when it is at the minimum distance of 147 million kilometers.
The earth's revolution around the sun takes a year (365 ¼ days) therefore the speed of revolution is about 29.6 kilometers per second. A normal year has only 365 days. The remaining traction of ¼ day is added once in four years to make a leap year of 366 days.
Explain the process of Revolution
The process of Revolution
Describe the result of the Earth's Revolution around the Sun
The result of the Earth's Revolution around the Sun
i. The four seasons of the year; summer, autumn, winter and spring. A Season is one of the distinct period into which the year may be divided.
In the northern hemisphere the summer season months are May, June and July. Autumn months are August, September and October, winter months are November, December and January and spring months are February, March and April.
In the Southern hemisphere summer has November, December and January. Autumn has February, March and April. Winter has May, June and July and spring has August, September and October.
Equinox refers to the period when the sun is overhead at the equator.
ii. Change in the position of the midday sun at different times of the year. As the earth revolves round the sun its position changes and makes it appear as if it is the sun moving.
iii. Varying lengths of day and night at different times of the year. The axis of the earth is inclined to its elliptical plane at a certain angle of 66.5 degrees. If the axis of the earth were vertical, the sun rays would always be overhead at the Equator, thus all places on the earth would always experiences 12 hours of daylight and 12 hours of night
The importance of the parallels and meridians
Define the Parallels and Meridians
The Parallels and Meridians
LATITUDE/PARALLELS
Latitude refers to the angular distance North or South of the equator measured in degrees, minutes and seconds. The equator is given a value of 00. It is an imaginary line which divides the Earth into two hemispheres. The Northern hemisphere has a latitude of 90o N and the Southern hemisphere has a latitude of 90o S.
Therefore, Parallels of latitude are particular lines joining all points on the surface of the earth and making an angle of 300 N with the equatorial plane.
THE IMPORTANT PARALLELS INCLUDE
i. Equator 0o
ii. Tropic of cancer 23.5 degrees N
iii. Tropic of Capricorn 23.5 degrees S
iv. Arctic Circles 66.5 degrees N
v. The Atlantic Circle 66.5 degrees S
LONGITUDE
Refers to the angular distance measured in degrees East and West of the Greenwich Meridian.
Prime Meridian is the line running through the poles and the Greenwich observatory near London. It is also known as Greenwich Meridian.
All lines of longitude are semi circles of equal length. Lines of longitude are also called meridians. There are 360 degrees in a circle, 1800 lie east of the Greenwich Meridian and the other 1800 west of Greenwich.
The Greenwich lines have been chosen by convention (meaning that any other lines could have served the same purpose).
CALCULATION OF TIME
The earth rotates on its axis from West to East once every twenty four hours. This means 3600 of longitude are covered in a period of 24 hours or 1 degree in four minutes. Places at a given meridian will experience midday at the same time. Time recorded along the same meridian is known as local mean time (LMT).
Example: When the local time of Accra is 2.00pm what will be the local time of Bangui 15 degrees E.
15 degrees - 0 degrees = 15 degrees
15 x 4 minutes = 60
60/60 = 1 hour
Accra 2.00 pm + 1.OO hour time difference = 3.00 pm
When the local times of Nairobi 45 degrees E is 10.00am. Find the meridian of Kinshasa where the local time is 9.00am.
10.00am Nairobi - 9.00am Kinshasa = 1.00 hour difference
10 = 4 minutes
hours = 60 minutes (60x1)
60 minutes / 4 minutes = 15 degrees
45 degrees E Nairobi – 15 degrees = 300 E Kinshasa
The longitude or Meridian of Kinshasa is 30 degrees E
What is the local time at Morogoro-Tanzania when it is noon at Kigali-Rwanda?
Procedure
i. Note the longitudinal position between the two points Kigali 300 E and Morogoro 450 E
ii. Find the difference in degrees of longitude between Kigali and Morogoro
45 degrees - 30 degrees = 15 degrees
iii. Multiply the difference by 4 minutes
150 x 4 minutes = 60 minutes
60 ÷ 60 = 1 hour
iv. The time difference is to be added (+) in case of places to the East of a point. In case of place to the West, the time difference is subtracted (-). Since Morogoro is to the East of Kigali, Morogoro time will be ahead of that of Kigali's by 1 hour, therefore time for Morogoro will be:
12.00 noon + 1 hour = 1.00 pm.
The local time at Morogoro is 1.00pm.
Explain the importance of a Great Circle
Importance of a Great Circle
GREAT CIRCLES
Any circle which divides the globe into hemispheres is a great circle. The equator is a great circle and Greenwich Meridian together with Meridian 1800 make another great circle. The number of great circles is limit less.
CHARACTERISTICS OF GREAT CIRCLES
i. All great circles divide the earth (sphere) into two hemispheres.
ii. A great circle is the largest possible circle that can be drawn on the surface of the sphere.
iii. The radius of great circles is the same as the radius of the earth.
IMPORTANT GREAT CIRCLES
i. All lines of longitudes (Meridians)
ii. Equator
USES OF GREAT CIRLCES
Great circles are used to plot routes for ships crossing the vast oceans and aircraft flying great distance in space. Ships and aircraft travel by following great circles in order to save fuel and time because the shortest route between two places is along the circle of the great circle which passes through them.
Discuss the importance of Parallels and Meridians
Importance of Parallels and Meridians
Calculate local time
Calculating Local time
Define time and time zone
Time and time zone
Time means duration or suitable moment for some purpose.
Time zone refers to a zone where standard time is accepted throughout a longitudinal zone 150 in width.
Explain the essence of time and time zone
Essence of time and time zone
The importance of time zones is to avoid the problems in telling time if every place had its own time set according to the local mean time.
The timetable of various human activities such as television and radio programs would be confusing if they had to show different times.
As the time varies from place to place to place, different stretches of land agreed to adopt the time from certain meridian, that time is known as standard time.
East African countries agreed to adopt standard time taken from meridian of 45oE.
When a whole stretch of land keeps to the same standard time that stretch of land forms a time zone.
Explain variation of standard time in a single country
Variation of standard time in a single country
Large countries like USA, China, etc have several standard time zones with each time zone covering about 15 degrees of longitude. There are 24 times zones in the world. The starting point for dividing the world into 24 times zones is the Greenwich Meridian. The standard time for Greenwich is known as the Greenwich Meridian time (GMT).
Define International Date Line
International Date Line
The International Date Line is the line where date is changed or calendar day begins. This line follows approximately the 1800 meridian.
Locate International Date Line
Locating International Date Line
When the time is 6.00pm on Monday 25th December, at Greenwich, the time at 1800 E longitude will be 12 hours ahead of Greenwich Mean Time. The time at 1800 E will be 6.00am on Tuesday 26th December. Therefore if one travels eastwards and crosses the date line, one will gain a day whereas one who travels westwards across the line will loose a day.
No comments:
Post a Comment