Earth Science Flashcards

Earth Science

The Origin of the Universe

The Expanding Universe:
- In the late 1920s, Edwin Hubble discovered that distant stars and galaxies are receding from Earth in every direction.
- The velocities of recession increase in proportion with distance.
- These findings imply that the Universe is expanding, as predicted by Einstein's Theory of General Relativity.
  - According to Hubble's hypothesis, the Universe was more condensed at a previous time.
  - All matter and energy were initially condensed in a very small and infinitely hot mass.
The Big Bang:
- A big explosion discharged matter and energy in all directions, occurring 13.8 billion years ago.
- Evidence supporting the expanding Universe includes the observation that distant galaxies are rapidly moving away from the Milky Way.
Structure, Composition, and Age of the Universe:
- The diameter of the Universe is infinite but at least 91 billion light-years (1 light-year = $9.4607 \times 10^{12}$ km).
- Its density is $4.5 \times 10^{-31}$ g/cm³.
- Hydrogen, helium, and lithium are the three most abundant elements.
- Stars are born out of clouds of gas and dust and eventually form galaxies.
- Instabilities within the clouds result in gravitational collapse, rotation, heating, and transformation into a protostar.
  - A galaxy is a cluster of billions of stars, and clusters of galaxies form superclusters.
- The Universe comprises all space and time, and all the matter and energy in it.
  - It is made of 4.6% baryonic matter (ordinary matter consisting of protons, electrons, and neutrons: atoms, planets, stars, galaxies, nebulae, and other bodies), 24% cold dark matter (matter that has gravity but does not emit light), and 71.4% dark energy (a source of anti-gravity).

The Solar System

The solar system comprises the Sun, eight planets, dwarf planets such as Pluto, satellites, asteroids, comets, other minor bodies such as those in the Kuiper belt, and interplanetary dust.
The asteroid belt lies between Mars and Jupiter.
Meteoroids are smaller asteroids and remnants of a failed planet.

The Planets

The Kuiper belt lies beyond Neptune (30 to 50 AU, 1 AU = Sun-Earth distance = 150 million km) and comprises numerous rocky or icy bodies.
The Oort cloud marks the outer boundary of the solar system and is composed mostly of icy objects.
The age of the Solar System is 4.6 billion years old based on the radioactive dating of meteorites.
Our solar system is located in the Milky Way galaxy, which is about 100 million light-years across (1 light year = $9.4607 \times 10^{12}$ km).
The solar system revolves around the galactic center once in about 240 million years.

Characteristics of Planets

All planets revolve around the Sun.
Orbits of the planets are elliptical and are on the same plane.
Much of the mass of the Solar System is concentrated at the center (Sun), while the outer planets hold angular momentum.
The periods of revolution of the planets increase with increasing distance from the Sun.
All planets are located at regular intervals from the Sun.
- The inner terrestrial planets (Mercury, Venus, Earth, and Mars) are made of materials with high melting points such as silicates, iron, and nickel.
  - They rotate slower, have thin or no atmosphere, higher densities, and lower contents of volatiles - hydrogen, helium, and noble gases.
- The outer four planets (Jupiter, Saturn, Uranus, and Neptune) are called gas giants because of the dominance of gases and their larger size.
  - They rotate faster, have a thick atmosphere, lower densities, and fluid interiors rich in hydrogen, helium, and ices (water, ammonia, methane).
- The composition and densities of the rocky planets are not too different from each other.

Rocky Planets

Venus is considered to be the Earth's twin planet because it has a very similar size and mass with the Earth.
Mars is about half the Earth's size.
Orbital period and velocity are related to the planet's distance from the Sun.
The rotational speed of Earth and Mars are very similar. The rotational speed of Venus is extremely slow.

Earth and its Unique Characteristics

The distance Earth orbits the Sun is just right for water to remain a liquid.
This distance from the Sun is called the habitable zone. The abundance of liquid water on Earth creates its blue color.

Seven things that make life on Earth possible

Earth orbits in the so-called Goldilocks zone, where the planet receives enough energy to allow water to exist as a liquid on its surface.
Water, in the liquid form, is one of the most essential prerequisites for life.
The Sun is a stable and long-lasting star.
The solar system is comfortably nestled in a safe harbor between major spiral arms.
The interstellar cloud of gas and dust that gave rise to Earth contained enough radioactive elements to power a churning core for billions of years, creating a magnetic field that protects the planet from dangers like solar flares.
Earth is tilted relative to the Sun, and wobbles as it spins. This tiny wobble can shift the climate.
Earth has an ozone layer to block harmful rays. Ancient plantlike organisms in the oceans added oxygen to the atmosphere and created a high-altitude layer of ozone.

The Earth System and Sub-systems

The Earth system refers to the planet's interacting physical, chemical, and biological processes.
The Earth system consists of the land, oceans, atmosphere, and poles.
It can be subdivided into four main sub-systems or spheres: the lithosphere, atmosphere, hydrosphere, and biosphere.

The Lithosphere

The lithosphere is the outer solid part of the Earth, including the crust and uppermost mantle.
It is made up of the brittle crust and the top part of the upper mantle.
The lithosphere is the coolest and most rigid part of the Earth.
The Earth has two types of lithosphere: oceanic and continental.
- Oceanic lithosphere is associated with oceanic crust and is slightly denser than continental lithosphere.
- Continental lithosphere is also called the continental crust. It is the layer of igneous, sedimentary rock that forms the continents and the continental shelves.
  - This layer consists mostly of granitic rock.
  - Continental crust is also less dense than oceanic crust, although it is considerably thicker (25 to 70 km versus 7-10 km).
  - About 40% of the Earth's surface is now covered by continental crust, but continental crust makes up about 70% of the volume of Earth's crust.
Most scientists believe that there was no continental crust originally on the Earth, but the continental crust ultimately derived from the fractional differentiation of oceanic crust over the eons.

Tectonic Plates

Tectonic activity describes the interaction of the huge slabs of lithosphere called tectonic plates.
There are nine major plates: North American, Pacific, Eurasian, African, Indo-Australian, Australian, Indian, South American, and the Antarctic.
The largest plate is the Pacific Plate at 39,768,522 square miles.
The driving force behind plate tectonics is the convection in the mantle.
Hot material near the Earth's core rises, and colder mantle rock sinks.
The convection drive plates tectonics through a combination of pushing and spreading apart at mid-ocean ridges and pulling and sinking downward at subduction zones.
All these three types of rock make up the Earth's lithosphere: sedimentary, igneous, and metamorphic.

Rocks

Sedimentary rocks are formed via weathering and transport of existing rocks, and then deposition, cementation, and compaction into sedimentary rock.
Igneous rocks are formed by cooling and crystallization of molten rock.
Metamorphic rocks are formed when heat or pressure is applied to other rocks.

The Atmosphere

Earth's atmosphere is about 300 miles (480 kilometers) thick, but most of it is within 10 miles (16 km) of the surface.
Air pressure decreases with altitude. At sea level, air pressure is about 14.7 pounds per square inch (1 kilogram per square centimeter).
At 10,000 feet (3 km), the air pressure is 10 pounds per square inch (0.7 kg per square cm).
There is also less oxygen to breathe.

Layers of the Atmosphere

Earth's atmosphere is divided into five main layers: the exosphere, the thermosphere, the mesosphere, the stratosphere, and the troposphere.
The gases in Earth's atmosphere include: Nitrogen (78%), Oxygen (21%), Argon (0.93%), Carbon dioxide (0.04%), and trace amounts of neon, helium, methane, krypton, hydrogen, and water vapor.

Troposphere

This layer is closest to Earth's surface. It is 4 to 12 miles (7 to 20 km) thick and contains half of Earth's atmosphere.
Air is warmer near the ground and gets colder higher up.
The process of condensation occurs here; that is why clouds are found here.
Nearly all of the dust in the atmosphere are in this layer.

Stratosphere

It is the second layer. It starts above the troposphere and ends about 31 miles (50 km) above ground.
Ozone is abundant here, and it heats the atmosphere while also absorbing harmful radiation from the Sun.
The air here is arid, and it is about a thousand times thinner than it is at sea level. Because of that, this is where jet aircraft and weather balloons fly.

Mesosphere

It starts at 31 miles (50 km) and extends to 53 miles (85 km) high.
The top of the mesosphere, called the mesopause, is the coldest part of Earth's atmosphere, with temperatures averaging about minus 130 degrees F (minus 90 C).
This layer is hard to study. Jets and balloons do not go high enough, and satellites and space shuttles orbit too high.
Scientists do know that meteors burn up in this layer.

Thermosphere

It extends from about 56 miles (90 km) to between 310 and 620 miles (500 and 1,000 km).
Temperatures can get up to 2,700 degrees F (1,500 C) at this altitude.
The air density is so low but still not outer space.
This is where the space shuttles flew and where the International Space Station orbits Earth.
This is also the layer where the auroras occur. Charged particles from space collide with atoms and molecules in the thermosphere, exciting them into higher states of energy.
The atoms shed this excess energy by emitting photons of light, which we see as the colorful Aurora Borealis and Aurora Australis.

Exosphere

The exosphere, which is the highest layer, is extremely thin.
This is where the atmosphere merges into outer space.
It is composed of very widely dispersed particles of hydrogen and helium.

Climate vs. Weather

Weather is a specific event-like a rainstorm or hot day-that happens over a few hours, days, or weeks.
Climate is the average weather conditions in a place over 30 years or more.
Earth's atmosphere is a jacket of gases that surrounds our planet. It keeps the planet warm, gives living organisms oxygen to breathe, and it is where the weather and climate occur.

Greenhouse effect

The greenhouse effect is a process that occurs when gases in Earth's atmosphere trap the Sun's heat.
This process makes Earth much warmer than it would be without an atmosphere.
The greenhouse effect is one of the things that makes Earth a comfortable place to live.
Human activities are changing Earth's natural greenhouse effect.
Burning fossil fuels like coal and oil puts more carbon dioxide into our atmosphere.
Too much of these greenhouse gases can cause Earth's atmosphere to trap more and more heat.
The main greenhouse gases are water vapor, carbon dioxide, methane, ozone, nitrous oxide, and chlorofluorocarbons.

The Hydrosphere

Water is the most abundant substance at the surface of Earth.
About 1.4 billion cubic km (326 million cubic miles) of water in liquid and frozen form make up the oceans, lakes, streams, glaciers, and groundwaters found there.
It is this enormous volume of water, in its various manifestations, that forms the discontinuous layer, enclosing much of the terrestrial surface, known as the hydrosphere.

Hydrologic cycle

Also called the water cycle.
Driven by solar energy, surface waters evaporate into the atmosphere, condense, and fall back to the surface as precipitation, shaping continents, creating rivers, and filling lakes.
This process has eroded billions of tons of surface material from the continents to the oceans, forming the major river deltas.
By far, most of the hydrosphere is saltwater-around 97%-but the 3% that is fresh is critical for terrestrial and freshwater species.

Global warming

Human contributions to greenhouse gases in the atmosphere are warming the Earth's surface-a process that is projected to increase evaporation of surface water and accelerate the hydrologic cycle.
In turn, a warmer atmosphere can hold more water vapor. Some evidence suggests global warming is already responsible for more extreme precipitation events.
Precipitation in a warming world is also projected to lead to departures from current timing and patterns of rainfall distribution. This phenomenon impacts biodiversity and the Earth system as a whole.

The Biosphere

It is intimately related to the other three Earth sub-systems.
Most living organisms require gases from the atmosphere, water from the hydrosphere, and nutrients and minerals from the geosphere.
Living organisms also require a medium for life and are adapted to inhabit one or more of the other three sub-systems.
Most of the biosphere, however, is contained within a shallow surface layer of the Earth, encompassing the lower part of the atmosphere, the surface of the geosphere, and approximately the upper 100 meters of the ocean.
Humans are part of the biosphere, although they are increasingly responsible for the creation of systems that may be largely artificial (such as cities).

Origin of the Biosphere

The biosphere has existed for about 3.8 billion years.
The biosphere's earliest life-forms, called prokaryotes, survived without oxygen. Ancient prokaryotes included single-celled organisms such as bacteria and archaea.

Philippine Biosphere Reserve

The Philippines currently has three UNESCO Biosphere Reserves. The first biosphere of the country was designated in 1977.
1. Albay Biosphere Reserve
  - Designated as the UNESCO Biosphere Reserve in 2016.
  - Located at the southern end of the Luzon Island of the Philippines, and covers some 250,000 hectares.
  - High conservation value with 182 terrestrial plant species, 46 of which are endemic.
  - Marine and coastal ecosystems comprise 12 species of mangrove, 40 species of seaweed or macro-algae, and 10 species of sea grass.
  - Five of the world's seven species of marine turtles are also found in Albay.
  - Home to Mayon Volcano, which is listed in the tentative list for UNESCO World Heritage Sites.
2. Palawan Biosphere Reserve
  - Designated as the UNESCO Biosphere Reserve in 1990.
  - Home to over 50 ethnolinguistic groups such as Pala'wan, Batak, Tagbanua.
  - Natural resources are highly diverse, including rich mineral deposits.
  - UNESCO notes Palawan has hundreds of endemic species, including 18 freshwater fish; 26 Philippine amphibians; 69 reptiles; 279 birds; and 58 terrestrial mammals, which include 16 species endemic only to Palawan.
  - 67 are classified as threatened. Of these, 42 are endemic to the province.
  - The reserve is home to the Puerto-Princesa Subterranean River National Park and the Tubattaha Reefs Natural Park (both are declared UNESCO World Heritage Sites).
  - It is also home to the El Nido-Taytay Managed Reserve, Mount Mantalangajan National Park, Coron Natural Biotic Area, and the Palawan Petrographs, all of which are in the Tentative List for UNESCO World Heritage Sites.
3. Puerto Galera Biosphere Reserve
  - Designated as the UNESCO Biosphere Reserve in 1977.
  - Situated on Mindoro Island.
  - Its 23,200 hectares make up the northern tip of Mindoro Island and are bounded to the north by the Verde Island Passage, to the west by the Camarong River and to the east by the municipality of San Teodoro.