Notes

Earth Science

Origin and Structure of the Earth - Planet Earth

Earth
- is the only planet in the solar system known to harbour life.
- only planet known to sustain life.
- is unique among planets in our solar system for having water in its liquid.
- is the only planet known to support life.
- is a dynamic body with many separate but highly interacting parts or spheres.

Saturn
- is mainly composed of the lightest two gases known, hydrogen and helium.

Water
- has several benefits.
- 75% of the earth's surface, 70% of all living things.

Organisms
- need water to support life, chemical reactions necessary to life occur mainly in water.

Different factors that support life on Earth
1. Distance from the Sun: Earth is at just the
appropriate distance from the Sun.

2. Atmosphere: Earth has an atmosphere, which provides gases for our survival.

3. Water: The presence of a universal solvent ensures that reactions can take place and nutrients can be moved around easily.

4. Time for development: We are lucky to have the Sun, which is and average star and has a long life, something which is essential for life to develop and sustain.

Four Spheres/Systems of Earth:

1. GEOSPHERE - includes all the stuff that make up the crust and the core of the earth.

2. HYDROSPHERE - is the total amount of water on a planet.

3. BIOSPHERE - is the layer of the planet Earth where life exists.

4. ATMOSPHERE - is a layer or a set of layers of gases.

THEORIES ON THE ORIGIN OF THE UNIVERSE

Earth Science
- the study of the Earth and its neighbors in space.

The Four Earth Sciences
Geology: Science of the Earth
- deals with the composition of Earth materials, Earth structures, and Earth processes.

Meteorology: Science of the Atmosphere
- study of the atmosphere and how processes in the atmosphere determines Earth's weather and climate.

Astronomy: Science of the Universe
- study of the universe and the heavenly bodies.

Oceanography: Science of the Oceans
- study of the Earth's oceans-their composition, movement, organisms and processes.

THE SOLAR SYSTEM

Solar System
- is made up of all the planets that orbit our Sun.

Satellite
- any such object in space that moves in a definite orbit around a larger body.

Formation of the Solar System Theories

Planetisimal Theory
- According to the planetesimal theory developed by T. C. Chamberlin and F. R. Moulton in the early part of the 20th cent., a star passed close to the sun. Huge tides were raised on the surface; some of this erupted matter was torn free and, by a cross-pull from the star, was thrust into elliptical orbits around the sun.

Nebular Theory
- developed by Immanuel Kant and given scientific form by P. S. Laplace at the end of the 18th cent., assumed that the solar system in its first state was a nebula, a hot, slowly rotating mass of rarefied matter, which gradually cooled and contracted, the rotation becoming more rapid, in turn giving the nebula a flattened, disklike shape.

The Sun
* is actually a large star.
* it appears as a ball of orange, yellow, or white light in the sky.
* is 860,000 miles wide, so about 109 Earths could fit inside the Sun!
* is about 93 Million Miles away from Earth.
* does not have any air or water, and is too hot for anything to live there.
* Sun's light takes 8 minutes to travel to Earth, at the speed of light which is 182,200 miles per second!

Layers of the Sun
- The inner layers are the Core, Radiative Zone and Convection Zone.
- The outer layers are the Photosphere, the Chromosphere, and the Corona

1. Core - source of all the Sun's energy.
2. Radiation zone - the region surrounding the core of the Sun.
3. Convection zone - Energy continues to move toward the surface through convection currents of the heated and cooled gas.
4. Photosphere - the deepest layer of the Sun that we can observe directly.
5. Chromosphere - an irregular layer above the photosphere where the temperature rises from 6000°C to about 20,000°C.
6. Corona - outermost layer of the Sun, starting at about 1300 miles (2100 km) above the solar surface (the photosphere).

Solar Activities
Sunspots
- dark, irregular patches of the photosphere.

Prominences
- a large, bright, gaseous feature extending outward from the Sun's surface, often in a loop shape.

Solar Flares
- sudden eruption which spray fountains of very hot gases into space.

The Planets

4 Inner Planet:

Mercury
- first planet from the Sun
- a big metal ball of iron
- contain almost no air
- just a little bit larger than Earth's moon
- smallest planet in our solar system fastest moving planet in our Solar System
- during the daytime the temperature is hotter than an oven; during the night, the temperature is colder than a freezer

Venus
- second planet from the Sun
- Earth's closest neighbor and the second brightest object in our night sky
- has more volcanoes than any of the other planets in our Solar System
- hottest planet in the Solar System atmosphere is made up from mainly carbon dioxide.

Earth
- third planet from the sun has one moon
fifth largest planet in our Solar System.
- Earth's atmosphere is mainly made up
of nitrogen, oxygen, and water vapor.
- There is a small amount of ozone in our atmosphere and this is what filters some of the damaging radiation from the Sun.
- The only planet in the solar system with an atmosphere that can sustain life.

Mars
- called the "Red Planet"
- fourth planet from the sun
- very dry and barren, but there is evidence that Mars was once covered with volcanoes, glaciers and flood waters.
- too cold for liquid water to exist for any length of time, but features on the surface suggest that water once flowed on Mars.
- Today, water exists in the form of ice in the soil, and in sheets of ice in the polar ice caps.

5 Outer Planet:

Jupiter
- the largest planet of all of the planets.
- is diameter is 11 times larger than Earth's diameter
- its mass is greater than the masses of all the other planets combined.
- a very stormy planet.

Saturn
- second largest planet in our Solar System and it is a gas giant like Jupiter
- lightest planet
- has beautiful rings made of ice and rocks.
- its atmosphere is cloudy and windy.

Uranus
- very cold, windy and, like most of the other planets, poisonous to humans.
coldest planet
- Like Jupiter and Saturn, Uranus is a gas giant.
- Scientists also believe that on the surface of Uranus there may be a huge ocean. And some scientists think that this ocean may be very hot, maybe even as hot as 2760 degree

Neptune
* a very windy place. No other planet in the Solar System has winds that are as strong as Neptune's
* the windiest planet
* has no definite surface layer. Instead, the gas transits into a slushy ice and water layer.
* most distant planet from the sun, Neptune is the third most massive. Despite its great size, it was the last planet to be discovered, because it lies so far away.

Pluto
* a dwarf planet.
* It is rocky and has one big moon.
* After 76 years of classification as a planet, Pluto was demoted in 2006 to a dwarf planet, in part because of its size but also because of its minor gravitational effects on the bodies around it. It remains one of the most well-known non-planetary bodies in the solar system.

Geologic Processes
Exogenic
- Originating ON or ABOVE the surface of the Earth.

Endogenic
- Originating WITHIN the Earth.

ROCK CYCLE
- It is a series of processes that create and transform the types of rocks in Earth's crust.

Weathering
- is the process of disintegration (physical and decomposition (chemical of rocks, breaking down o rocks into smaller particles.

Two Types of Weathering
Mechanical (physical weathering)
- breaking down of rocks without changing its composition.
Chemical Weathering
- there are changes in the composition of rocks due to chemical reaction.

Mechanical Weathering Factors
* PRESSURE - Squeeze the spaces out of minerals within the rock.

* TEMPERATURE - Expands, Contracts

* FROST WEDGING - Collective term for several mechanical processes created by FREEZING of water into ICE.

* ABRASION - Breaking down or wearing away of rocks by mechanical action of other rocks.

* ORGANIC ACTIVITY - Growing roots or plant acids.

* HUMAN ACTIVITIES - like biking, driving.

* BURROWING ANIMALS

Chemical Weathering

* DISSOLUTION - rocks or minerals are dissolved by water.
* HYDROLYSIS - breaking down of rocks by acidic water to produce clay and soluble salts.
* OXIDATION - breaking down of rocks by oxygen.

EROSION
- is the separation and removal of weathered rocks due to different agents like water, wind, and ice.

Mass Wasting
- is the movement of sediments downslope under the influence of gravity.

Deposition
- is the process in which the weathered materials carried out by erosion stle down in a particular location.