ASVAB Earth and Space Science

Layers of the Earth

Crust, Mantle, Outer Core, Inner Core

Crust

Earth’s surface and has two types: continental, which forms each of the continents and is about 12 miles thick, and oceanic, which lies beneath the oceans and is about 5 miles thick. The solid rock below the crust is the mantle, which accounts for about two-thirds of Earth’s mass

Mantle

Accounts for about two-thirds of Earth’s mass and is classified into layers based on the composition of the elements in each and the way each responds to earthquakes: Mesosphere, Asthenosphere, and Lithosphere

Mesophere

Located in the lower mantle, surrounding Earth’s outer core. In the mesosphere, temperatures are high enough to melt rock, but a tremendous amount of pressure keeps all the materials solid

Asthenosphere

In the middle part of the mantle. Rocks there are solid but they move like glaciers do (plastic flow). The temperatures in the asthenosphere are still very high which can lead to some melting

Lithosphere

The uppermost part of Earth’s mantle, and it’s attached to the curst. The rocks in the lithosphere are solid, thick, and brittle, like the crust, but they’re made of different materials from the crust

The Core

Earth’s superheated metal center and has two parts: the inner core and the outer core. The outer core is about 1,800 miles (2,900 kilometers) below your feet, and the inner core is about 3,200 miles (5,200 kilometers) down

Sedimentary

Formed by sediment (such as particles of sand, seashells, and other materials), sedimentary rocks “grow” in layers. Over a long period of time, sediment hardens — but it’s still considered soft, as far as rocks go. This type of rock most often contains fossils

Metamorphic

These rocks form because of the heat and pressure below Earth’s surface. These rocks sometimes have shiny crystals inside them and may form layers that look like ribbons, such as marble and gneiss

Igneous

Magma, the super-heated molten rock simmering below Earth’s crust and above its mantle, collects in pockets called magma chambers beneath volcanoes that eventually erupt (between 1,000 - 3,000 degrees Fahrenheit). When magma comes out through a volcano it’s lava. Cooled lava forms Igneous rocks. Magma that cools quickly is shiny and glasslike; when it cools slowly, crystals can form. Obsidian and granite are types of igneous rock

Troposphere

Extends between 6 and 12 miles above Earth and is higher at the equator than it is the poles. This layer is where the jet stream (fast-flowing, narrow air currents) is located and where almost all weather changes occur. Air is warmest near ground-level in the bottom of this layer and becomes colder at higher levels.

Stratosphere

Extends about 30 miles. A major reported cause of ozone depletion is the presence of chlorofluorocarbons in Earth’s stratosphere. CFCs undergo a series of chain reactions, which ultimately lead to the destruction of the ozone layer

Mesophere

Extends about 50 miles. Millions of meteors burn up daily in the mesosphere as a result of collisions with the gas particles contained there

Ionosphere

Extends about 70 miles. This layer reflects most radio waves, making it important to communications. Scientists diagree among themselves as to whether the ionosphere is a separate atmospheric layer of whether it’s part of the thermosphere

Thermosphere

Extends about 350 miles. The International Space Station has a stable orbit within the upper part of the thermosphere, between 208 and 285 miles up

Exosphere

Extends about 6,200 miles. It’s only from the exosphere that atmospheric gases, atoms, and molecules can escape into outer space. No boundary exists between the exosphere and space; therefore, exosphere is sometimes used synonymously with outer space

Gases in the atmosphere

The entire atmosphere is made from a variety of gases - trace amounts of neon, helium, krypton, methane and hydrogen.

Nitrogen

Gas that makes up 78% of the Earth’s atmosphere

Oxygen

Gas that makes up 21% of the Earth’s atmosphere

Argon

Gas that makes up .93% of the earth’s atmosphere

Carbon dioxide

Gas that makes up .04 percent of the earth’s atmosphere

Magnetosphere

An invisible globe of space around the planet that’s controlled by the Earth’s magnetic field. Deflects solar wind. Because Earth’s core is made from iron and other hot, liquid metals that create electrical currents, it’s there — and its protective forces come out of the Southern Hemisphere (South Pole) and travel back into the planet in the Northern Hemisphere (North Pole)

Cirrus

Thin, wispy, high clouds that usually form between altitudes of 20,000 and 40,000 feet. Cirrus clouds generally indicate rain or snow in the near future, when they thicken and lower, becoming other types of clouds

Cumulus

White, puffy pillows, often flat-bottomed with round tops that usually form at altitudes between 1,000 and 5,000 feet. Cumulus clouds are common during fair weather, but when they gather they cause heavy rains

Stratus

Broad, flat, and low-hanging clouds that usually form between 2,000 feet but sometimes form as high as 4,000 feet. If close the ground, stratus clouds may produce drizzle

Cirro-

The prefix given to high clouds (base above 20,000 feet)

Alto-

The prefix given to midlevel clouds (base about 6,000 and 20,000 feet)

Nimbo- or -nimbus

Added to the beginning of cloud name or added to the end means the cloud is producing precipitation

Kelvin

Scientists have theorized that the coldest anything can get is -273.15 degrees Celsius. They believed that at his temperature, molecular motion would stop. This temperature, often called absolute zero, is assigned to the number 0 on the this scale. The freezing point of water is 273.15 on this scale. The boiling point would be 373.15

Temperature Conversions

1. Celsius to Fahrenheit = (9/5)C + 32

2. Fahrenheit to Celsius = (5/9) (F-32)

3. Kelvin Scale Temperatures is just C plus 273.15

Vernal equinox

The first day of spring - the vernal equinox - is the day the sun crosses from south of the equator to north of it

Summer solstice

The day the sun reaches the farthest point north on the ecliptic (the path the sun takes each year)

Autumnal equinox

The sun crosses the equator toward the south and kicks off fall on the autumnal equinox

Winter solstice

The day the sun is as far south as possible on the ecliptic

Planetary Composition

The inner (first) four planets consist chiefly of iron and rock. They’re known as terrestrial planets because they’re somewhat similar in size and composition. The outer planets known as Jovian (Jupiter-like) planets, are giant worlds with thick, gaseous outer layers. Almost all their mass consists of hydrogen and helium, giving them composition more like that of the sun than of Earth. Beneath their outer layers, the giant planets have no known solid surfacers. The pressure of their thick atmosphere turns their inside liquid, though they may have rocky cores. Rings of dust, rock, and ice chunks encircle all the giant planets not just Saturn

0 Moons

Mercury and Venus

1 Moon

Earth

2 Moons

Mars

63 Moons

Jupiter

61 Moons

Saturn

27 Moons

Uranus

13 Moons

Neptune

Mesozoic Era

Dinosaurs made their first and last appearances during this era between 230 and 66 million years ago