- The celestial bodies
The celestial bodies: they include stars, planets, moons and rocky.
The light year: it is the distance covered by the light
In a year. It equals 9.467 x 1012 Km
Galaxies: they are the biggest units is forming the universe
• galaxies are very big include collection of stars
• the galaxy which our universe belongs to is milky way or chopped hay .
• the solar system : it consists of the sun and eight planets revolve around it and contains some components as asteroids , meteors , meteorites
and comets.
• the planets : they are eight spherical opaque bodies
Revolve around the sun in elliptical (oval) path
This path is perpendicular to the sun's axis.
• the planet divided into inner planets as mercury , Venus , earth and mars
• inner planets characterized by:
• they are small solid bodies
• They have atmosphere except mercury.
• their density high from 3.3 to 5.5 g/cm3
Outer planets as Jupiter, Saturn, Uranus and Neptune.
They are big size
They have low density from 0.7 to 1.3 gm/cm3
They are gaseous from hydrogen and helium
The hydrogen exist in solid state due to high pressure and coldness of this planets
They have large numbers of moons.
• Stars: they are big sized bodies emit heat and light.
• Moons: they are small planets affected by gravity of larger planets and rotate around them.
• The moon is satellite of earth.
• asteroids: they are celestials bodies rotate around the sun in region called belt of wanderer asteroids
Between inner and outer planets (mars – Jupiter)
Meteors: they are small rocky masses fall within atmosphere of earth; they burn completely due to friction with air and form luminous arrows in sky.
Meteorites: they are huge solid rocky that fall and not burn completely - some parts reach to earth.
• The biggest meteorites fall in south west of Africa about 80 tons.
Comets: they consists of two parts
1- head : contains icy spheres which are mixture of
Gases (carbon dioxide, nitrogen and methane gas)
And rocky part – dust and water molecule
2- Tail: it considered gaseous cloud.
• comets revolve around the sun in elliptical orbits
• the most famous comet is Halley .
Telescope: it is an instrument used in identifying
The celestial bodies.
Type of telescope
1- reflecting telescope 2- refracting telescope
The earth
• the earth is the planet which we live
• the earth rotate around the sun in 365.25 days
• the distance between the earth and the sun is 150 million kilometers .
• characteristics of earth
1- earth' atmosphere : contain gases as
*Oxygen 21 %: necessary for respiration and burning
* Nitrogen 78% : reduce effect of oxygen in burning and formation of protein for plant .
* Carbon dioxide 0.03%: necessary for plant to make photosynthesis process.
2- Earth hydrosphere.
* Water represents about 71% on the earth surface
* Salty water as seas and Oceans
* Fresh water as rivers, lakes, snow of two poles
* Ground water exist in the pores and cracks of the rocks that form the solid mass of earth crust
- Water necessary for animal and plant.
3- The suitable temperature: due to position of earth from the sun
4- The gravity: it cause keeping the living organisms and the atmosphere fixed on its surface .
5- The suitable air pressure : it is about 76 Cm.Hg
The mass of earth about 5.9 x10 24 K
The volume of earth : its diameter is 6368 Km
*the earth consists of layers which are
Earth crust, the mantle, the core
The earth crust : it is relatively light from ( 8- 50 ) Km
- The mantle is a rocky layer its thickness about 2885 Km
- The outer core is molten metals due to high pressure ( 2270 )Km
- The inner core contains solid metal as iron and nickel. ( 1216)Km
Rocks and minerals
Rocks: they are natural solid materials exist in earth crust and formed from one mineral or group of minerals.
• the soil : it is non compacted layer covers earth's crust
Type of earth's rocks:
* Igneous rocks * sedimentary rocks * metamorphic
First -the igneous rocks: they are rocks formed from solidification of magma under earth 'crust or lava on earth's surface.
• magma : it is hot liquid underneath earth crust
• lava : it is the material of magma which reach earth's crust
• from igneous rocks :
1-plutonic rocks: they are rocks formed inside earth's crust at great depths.
* it is large sized crystals .
1- Volcanic rocks: they are rocks formed when magma reach earth's surface, they extend from volcanoes.
From examples for igneous rocks
* Granite: its colour is grey or pink - heavy, rough, solid cohesive and it isn't easily broken.
Exist in eastern desert of Sinai Peninsula
The mineral that form its rocks
- Quartz (silicon dioxide): it has glassy luster (shine)
- Feldspar: (aluminium silicate) and elements as calcium, sodium and potassium
- Mica: it consists of thin bright sheets or dark brown.
* volcanic rocks as :
Basalt: it is dark colour rocks, its components can't see by naked eye
It is found in Egypt in Abou-Zaabal and El-Fayoum.
The minerals formed basalt
- olivine ( magnesium and iron silicate ): it has olive colour and glassy luster
- pyroxene : it is mixture of iron silicate and calcium
it has green colour and prism shape .
- feldspar
Second: sedimentary rocks:
• They cover about 75% from earth crust and about 5 % of the volume of earth's rocks.
Formation sedimentary rocks
a- erosion ( fragment and disintegration ) of igneous and metamorphic
b- transportation by water or by air
c- Sedimentation ( deposition ) to another place forming rocks
• example for sedimentary rocks
• sandstone : consists of sand grains , quartz , feldspar and mica
• limestone ( calcium carbonate ) : consists of calcite minerals
It reacts with hydrochloric acid and effervescence take place due to precipitation of calcium.
Third: metamorphic rocks: when igneous or sedimentary rocks subjected (affect) to high temperature and pressure they convert into metamorphic rocks
Example: marble
• Marble result from transformation of limestone
• Its colour is white or colored
Earth quakes and volcanoes
Earth quakes: they are rapid and successive shakes
Of the ground which takes place one after other.
Causes of earthquakes:
1- breaking in crust and formation of faults
*Faults: it is a fracture in the earth crust that lead to sliding
of rocks in vertical or horizontal on both side of fracture.
2- volcanoes : that the eruption of volcanoes may accompanied
with shaking of ground due to movement of molten materials
and trapped gases before or during coming out of the surface .
* Earth quakes is measured by richer scales
* Seismograph apparatus used in:
1- Records the earthquakes intensity
2- Timing of occurrence
3- Its duration
* Structure of seismograph:
1- Vertical stand on the ground
2- Spring fixed on the sand
3- Metal weight at the end of spring
4- Arm end with pencil
5- Recording cylinder touch with the pencil
* Seismic record: it is a zigzag line produced by the earth quake recording.
- the cylinder warpped with paper , it rotates slowly
Harm of earth quakes:
1-loss in spirits and building
2-destroy the roads
3-destroy submerged coastal cities
benefits of earth quakes :
1-know the earth internal structure and study seismic waves .
safety precaution at occurrence of earth quake
2- at building you must sit under hard table .
3-at car remain inside
4-go away from building.
* Tsunami waves: it is high waves in oceans destroy submerged coastal
• After earthquake happen consequences happen from 12 – 24 hour.
• after earthquake so we should
1-cut electricity , water and gases from building
2-go to open places
3-follow broadcasted by radio .
Volcanoes
volcano : it is an opening in earth 's crust through which molten materials (lava ) and trapped gas going out side the earth surface .
* Direct volcano caused due to the presence weak part of earth's crust.
• volcanoes consist of
1-Volcanic vent: it is an opening at the top of volcano.
2-The pipe ( neck ): it is a cylindrical cavity that connect earth surface
with earth's interior
* It allows magma to move to the surface of earth.
3-The cone : it is the body of volcano that consists of
Molten material after solidification and accumulation around the volcano vent
• the material ejected during volcano eruption .
1-Fragment material: it is from big object to volcanic ashes.
* Volcanic ashes: it is fine fragment ejected from volcano.
2-lava : it is molten material spread on volcanic side
3-Volcanic gases: they are mixed gases from water vapour , oxides of carbon and nitrogen and sulphur .
• harms of volcanoes :
1- lava destroy whole town and villages
2-Poisonous gases spread along distances.
3- Fire in forest and cultivated land.
Benefits of volcanoes:
1-the thermal energy used in generate electricity
2-the soil from volcanoes are more fertile .
3-the volcanic rocks has great value
4-forming new island to increase the area of land .
• safety precaution for volcanoes
1-follow the forecasting to avoid poisonous gases
2-free the area neighboring from people .
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ملخص العلوم الوحدة الثالثة
atwa- عضو فعال
- عدد المساهمات : 114
نقاط : 55391
تاريخ التسجيل : 22/04/2009
العمر : 49
M A Yossef- عضو فعال
- عدد المساهمات : 74
نقاط : 54304
تاريخ التسجيل : 14/07/2009
العمر : 30
Thanks Mr/Atwa