Earth: The Habitable Planet

Earth: The Habitable Planet

• Earth is also known as "Terra" or the "Blue Planet."
• The sun must survive long enough for planets to develop life
• The sun is is about 4.6 billion years old.
• A planet must exist in a region where water can remain liquid, also known as the "Goldilocks Zone."
• Earth is about 4.54 billion years old.
• Earth is composed of different subsystems.
• Earth is a complex system of interrelating physical, chemical, and biological processes.

Goldilocks Zone

• A Goldilocks zone is a region around a star that receives enough heat and solar energy to maintain a temperature that is suitable for liquid water.

Factors for Habitability

• Five categories make Earth a habitable planet: temperature, water, energy, atmosphere, and nutrients.

Temperature

• Life on Earth seems to be limited to a temperature range of -150°C to 115°C.

Water

• Water is also an important ingredient in different biological processes.
• Liquid water is necessary for life to exist.

Energy

• With a steady input of either light or chemical energy, cells can run the chemical reactions necessary for life.

Atmosphere

• Earth's atmosphere is about 100 miles thick.
• The atmosphere keeps the surface warm and protects it from radiation and meteorites.

Nutrients

• Nutrients are used to build and maintain an organism's body.

Earth as a Closed System

• The amount of matter within Earth as a closed system is fixed.
• An example is the volume of mineral resources a planet has: the resources used can never be regenerated and the waste produced cannot really be disposed of.
• Changes within one subsystem eventually cause changes in others.
• An example of this is the Mount Pinatubo Eruption.
• The 1991 Mount Pinatubo eruption caused temporary changes on global surface temperature and forever changed the landscape of Central Luzon.

Earth's Spheres

• There are four Earth Spheres: Geosphere, Hydrosphere, Atmosphere and Biosphere.

Geosphere

• The geosphere comes from the Greek word "Geo" which means Earth, ground, or land.
• The geosphere is divided into three layers.
• A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them.
• The three layers of the geosphere include the crust, the mantle, and the core.

Crust

• The crust can be compared to the skin of an apple, and contains 1% of Earth's volume.
• The crust has two types: continental crust and oceanic crust.
• The continental crust is thicker and found under continents, about 35 km thick on average.
• The oceanic crust is thinner and found under ocean basins, about 7 km thick on average.
• On land at sea level, the crust is about 35 km thick, is about 70 km thick in mountainous regions, and is about 7 km thick at the bottom of the ocean.
• The lithosphere includes a rigid layer that is rocky, like the crust. "Lithos" means "Stone."
• The lithosphere includes both the Earth's crust and the solid part of the upper mantle.
• The asthenosphere is plastic-like, solid but softer. "Asthenes" means "weak".

Mantle

• The Mantle makes up 84% of earth's volume.
• The mantle is made up of silicate rocks.
• The movement of the mantle causes the movement of the Earth's plates.
• The warmer rocks goes up while cooler rocks goes down.

Core

• The core is the densest layer and makes up about one-third of Earth's mass.
• The core is divided into the outer core and the inner core.
• The outer core is a liquid layer composed mainly of molten iron and nickel that has a thickness of about 2,300 kilometers.
• The inner core is the solid, central part of the Earth that has a radius of about 1,220 kilometers and is composed of solid iron and nickel.
• Earth's magnetic field matters because the earth's magnetic field protects the earth from sun's harmful Solar wind.

Hydrosphere

• Earth is a blue planet or blue marble.
• The hydrosphere is 71% of Earth's overall surface.
• About 70% of Earth's freshwater is found in ice caps, glaciers, and snow.
• 97% is the earth is oceans, 3% is freshwater, 79% of the freshwater makes up ice caps and glaciers.
• The hydrosphere includes oceans, lakes, rivers, streams, groundwater and glaciers.
• Up to 60% of the human adult body is water.
• The brain and heart are composed of 73% water, and the lungs are about 83% water. The skin contains 64% water, muscles and kidneys are 79%, and even the bones are watery: 31%.
• Water could be in liquid, solid or gaseous form.
• Water has a neutral pH.
• Water is a good conductor of heat and energy.
• Water has high specific capacity.
• Water is a universal solvent.
• The interaction of the geosphere and hydrosphere causes the shaping of Earth's surface
• The sun's energy is the power that drives the water cycle.

Atmosphere

• The atmosphere refers to the layer of gases that surrounds the Earth.
• It consists mainly of nitrogen (78%) and oxygen (21%), along with small amounts of carbon dioxide (.04%) argon and other gases.
• The atmosphere provides vital protection, regulates temperature, and supports weather and climate systems.
• The atmosphere is also known to be the "blanket of our planet".
• The atmosphere is important in maintaining heat coming from the sun to keep us warm even at night.
• The sphere is divided into different layers: Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere.
• The exosphere is the outermost layer of Earth's atmosphere located above the thermosphere, extremely thin and gradually fades into space.
• The thermosphere is the fourth layer of Earth's atmosphere that is primarily composed of individual gas molecules, such as oxygen and nitrogen.
• The thermosphere absorbs highly energetic solar heat with temperature beyond 1000 °C.
• The mesosphere is the third layer of Earth's atmosphere that extends approximately from an altitude of about 50 kilometers to 85 kilometers above the Earth's surface.
• The mesosphere is characterized by thin air and low atmospheric pressure. It is the coldest layer as the temperature can drop up to -90 °C.
• The stratosphere the layer of Earth's atmosphere located above the troposphere that extends roughly from an altitude of about 12 kilometers to 50 kilometers above the Earth's surface.
• This layer is home to the ozone layer which shields the Earth from harmful UV radiation.
• The troposphere is the lowest layer of Earth's atmosphere, extending from the Earth's surface up to an average altitude of about 12 kilometers.
• The troposphere is the densest layer among the other layers.
• It is the layer where weather occurs, and it is where people live and breathe.

Biosphere

• The biosphere is the biological component of Earth.
• Anthroposphere/ "Human Sphere" is part of the Earth that has been modified by humans.
• The Laws of thermodynamics state that energy can neither be created nor destroyed and that no transfer of energy is 100% complete.
• The Energy-Food Pyramid shows the relationship between trophic levels and illustrates the 10% Rule where = 10% of the energy "harvested" at a lower trophic level is transferred up to the next higher trophic level.
• A food chain shows just 1 path of energy while a food web shows all possible energy paths.
• There are 5 types of ecological relationships: mutualism, commensalism, parasitism, competition, and predation.
• Mutualism describes an interaction that benefits both species.
• Commensalism is an interaction where one species benefits and the other remains unaffected.
• Parasitism occurs when one organism benefits and the host suffers.
• Ecological competition is the struggle between two organisms for the same resources within an environment.
• Predation includes any interaction between two species in which one species benefits by obtaining resources from and to the detriment of the other.