Earth 1
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EVOLUTION OF EARTH
HELLO FRIENDS…..!
DO YOU KNOW WHICH PLANET IN THE UNIVERSE SUPPORTS LIFE..?
YES IT IS
EARTH
YES YOU ARE RIGHT. VERY GOOD
NOW LET US LEARN ABOUT THE “EVOLUTION OF EARTH”
INTRODUCTION • Earth is the third planet from the Sun and the fifth largest:
orbit: 149,600,000 km (1.00 AU) from Sun diameter: 12,756.3 km mass: 5.972e24 kg
HOW OLD IS THE EARTH? • Earth formed 4.6 billion years ago from the inner solar nebula.
EVOLUTION OF EARTH • Evolution is the process by which all living things have developed from primitive organisms through changes occurring over billions of years, a progression that includes the most advanced animals and plants. After the Earth was formed, there were many planetesimals still in the Solar System. These bombarded the Earth in what is called the Great Bombardment, which was so intense that the Earth's temperature increased significantly. In such a state, differentiation occurred, in which the heavier elements, such as iron and nickel, sunk to the center, and the lighter elements floated to the top. This led to a layered structure of the Earth.
LAYERS OF EARTH
• The Earth is divided into several layers which have distinct chemical and seismic properties (depths in km): •0- 40 Crust •40- 400 Upper mantle •400- 650 Transition region •650-2700 Lower mantle •2700-2890 D'' layer •2890-5150 Outer core •5150-6378 Inner core
These layers are grouped as follows: •
Inner Core: The inner core, about 1200 km thick, consists of mainly iron and nickel in a molten state due to the intense heat and pressure. • Outer Core: The outer core is about 2300 km thick, and consists also mainly of nickel and iron, but in a solid form. • Mantle: The mantle, about 2900 km thick, is rich in lighter elements such as oxygen, silicon, magnesium, and iron. • Crust: The crust is is composed of the lightest elements of the earth, and varies in thickness from about 10 km beneath the oceans to about 70 km thick beneath the continents.
STAGES OF EVOLUTION Four main stages of evolution:
• Two sources of heat in Earth’s interior •Potential energy of infalling material •Decay of radioactive material
METEORITE IMPACTS ON EARTH • Over 150 impact craters found on Earth. • Famous example: Barringer Crater near Flagstaff, AZ: • Formed ~ 50,000 years ago by a meteorite of ~ 80 – 100 m diameter
EARTH’S INTERIOR • Earth’s interior gets hotter towards the center. • Earth’s core is as hot as the sun’s surface; • metals are liquid near the core.
The Role of Earth’s Magnetic Field
• Earth’s magnetic field protects Earth from highenergy particles coming from the sun (solar wind).
EARTH’S ATMOSPHERE • Only about 1/800 of the Earth’s radius! Which is the most common gas in Earth’s atmosphere? Oxygen Nitrogen Carbon dioxide Methane Water vapor
SOURCES OF ATMOSPHERIC GAS
• Outgassing : Release of gasses bound in compounds in the Earth’s interior through volcanic activity • Later bombardment with icy meteoroids and comets
ATMOSPHERIC STRUCTURE • The Interactions between Light and Molecules • Efficient interaction with Ozone (O3). • Scattering => Blue sky; red morning/evening sun • Greenhouse Effect!
THE TEMPERATURE STRUCTURE OF EARTH’S ATMOSPHERE • • • •
Ionosphere: Heated by UV and X-rays from space Mesosphere: Heated by X-rays from space. Stratosphere: Heated by UV radiation from space Troposphere: Heated by greenhouse effect
Ozone Layer • Atmosphere gets colder at larger distance from heat sources.
PROJECT ON EVOLUTION OF EARTH
SUBMITTED BY Mrs.SARABJIT KAUR Mrs.REKHA CHABRA S. Pritpal Singh
GUIDANCE:Mrs.SATPAL KAUR(CT) Ms.SHIVANI NANDA(CF) Ms.KAMALPREET KAUR(CF)
REFERENCES:RETREIVED FROM MICROSOFT ENCARTA
ENCYCLOPEDIA(evolution) CLASS XTH TEXT BOOK. WEBSITE: http\\encarta.com\
http\\Gould The Evolution of Life on the Earth.com http\\Understanding divergent evolution of Earth-like planets The
HELLO FRIENDS…..!
DO YOU KNOW WHICH PLANET IN THE UNIVERSE SUPPORTS LIFE..?
YES IT IS
EARTH
YES YOU ARE RIGHT. VERY GOOD
NOW LET US LEARN ABOUT THE “EVOLUTION OF EARTH”
INTRODUCTION • Earth is the third planet from the Sun and the fifth largest:
orbit: 149,600,000 km (1.00 AU) from Sun diameter: 12,756.3 km mass: 5.972e24 kg
HOW OLD IS THE EARTH? • Earth formed 4.6 billion years ago from the inner solar nebula.
EVOLUTION OF EARTH • Evolution is the process by which all living things have developed from primitive organisms through changes occurring over billions of years, a progression that includes the most advanced animals and plants. After the Earth was formed, there were many planetesimals still in the Solar System. These bombarded the Earth in what is called the Great Bombardment, which was so intense that the Earth's temperature increased significantly. In such a state, differentiation occurred, in which the heavier elements, such as iron and nickel, sunk to the center, and the lighter elements floated to the top. This led to a layered structure of the Earth.
LAYERS OF EARTH
• The Earth is divided into several layers which have distinct chemical and seismic properties (depths in km): •0- 40 Crust •40- 400 Upper mantle •400- 650 Transition region •650-2700 Lower mantle •2700-2890 D'' layer •2890-5150 Outer core •5150-6378 Inner core
These layers are grouped as follows: •
Inner Core: The inner core, about 1200 km thick, consists of mainly iron and nickel in a molten state due to the intense heat and pressure. • Outer Core: The outer core is about 2300 km thick, and consists also mainly of nickel and iron, but in a solid form. • Mantle: The mantle, about 2900 km thick, is rich in lighter elements such as oxygen, silicon, magnesium, and iron. • Crust: The crust is is composed of the lightest elements of the earth, and varies in thickness from about 10 km beneath the oceans to about 70 km thick beneath the continents.
STAGES OF EVOLUTION Four main stages of evolution:
• Two sources of heat in Earth’s interior •Potential energy of infalling material •Decay of radioactive material
METEORITE IMPACTS ON EARTH • Over 150 impact craters found on Earth. • Famous example: Barringer Crater near Flagstaff, AZ: • Formed ~ 50,000 years ago by a meteorite of ~ 80 – 100 m diameter
EARTH’S INTERIOR • Earth’s interior gets hotter towards the center. • Earth’s core is as hot as the sun’s surface; • metals are liquid near the core.
The Role of Earth’s Magnetic Field
• Earth’s magnetic field protects Earth from highenergy particles coming from the sun (solar wind).
EARTH’S ATMOSPHERE • Only about 1/800 of the Earth’s radius! Which is the most common gas in Earth’s atmosphere? Oxygen Nitrogen Carbon dioxide Methane Water vapor
SOURCES OF ATMOSPHERIC GAS
• Outgassing : Release of gasses bound in compounds in the Earth’s interior through volcanic activity • Later bombardment with icy meteoroids and comets
ATMOSPHERIC STRUCTURE • The Interactions between Light and Molecules • Efficient interaction with Ozone (O3). • Scattering => Blue sky; red morning/evening sun • Greenhouse Effect!
THE TEMPERATURE STRUCTURE OF EARTH’S ATMOSPHERE • • • •
Ionosphere: Heated by UV and X-rays from space Mesosphere: Heated by X-rays from space. Stratosphere: Heated by UV radiation from space Troposphere: Heated by greenhouse effect
Ozone Layer • Atmosphere gets colder at larger distance from heat sources.
PROJECT ON EVOLUTION OF EARTH
SUBMITTED BY Mrs.SARABJIT KAUR Mrs.REKHA CHABRA S. Pritpal Singh
GUIDANCE:Mrs.SATPAL KAUR(CT) Ms.SHIVANI NANDA(CF) Ms.KAMALPREET KAUR(CF)
REFERENCES:RETREIVED FROM MICROSOFT ENCARTA
ENCYCLOPEDIA(evolution) CLASS XTH TEXT BOOK. WEBSITE: http\\encarta.com\
http\\Gould The Evolution of Life on the Earth.com http\\Understanding divergent evolution of Earth-like planets The
