Earth
Fromabundant
Adjective
air current
Noun
flowing movement of air within a larger body of air.
Noun
a large volume of air that is mostly consistent, horizontally, in temperature and humidity.
algae
Plural Noun
(singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.
Noun
the distance above sea level.
ancestor
Noun
organism from whom one is descended.
Noun
an underground layer of rock or earth which holds groundwater.
archaea
Plural Noun
(singular: archaeon) a group of tiny organisms often living in extreme environments, such as ocean vents and salt lakes.
Archaean
Noun
geological time period between 3.8 billion years ago and 2.5 billion years ago.
Noun
region at Earth's extreme north, encompassed by the Arctic Circle.
asteroid
Noun
irregularly shaped planetary body, ranging from 6 meters (20 feet) to 933 kilometers (580 miles) in diameter, orbiting the sun between Mars and Jupiter.
asteroid belt
Noun
area of the solar system between the orbits of Mars and Jupiter filled with asteroids.
astronomical unit
Noun
(AU) (150 million kilometers/93 million miles) unit of distance equal to the average distance between the Earth and the sun.
astronomy
Noun
the study of space beyond Earth's atmosphere.
Noun
layers of gases surrounding a planet or other celestial body.
augment
Verb
Noun
brightly colored bands of light, visible around Earth's geomagnetic poles, caused by solar wind interacting with particles in Earth's magnetic field.
Noun
organism that can produce its own food and nutrients from chemicals in the atmosphere, usually through photosynthesis or chemosynthesis.
Noun
an invisible line around which an object spins.
axis of rotation
Noun
single axis or line around which a body rotates or spins.
Plural Noun
(singular: bacterium) single-celled organisms found in every ecosystem on Earth.
basalt
Noun
type of dark volcanic rock.
Noun
a dip or depression in the surface of the land or ocean floor.
Noun
part of the Earth where life exists.
body water
Noun
amount of liquid water in an organism's body.
Noun
line separating geographical areas.
brittle
Adjective
fragile or easily broken.
Cambrian
Noun
(540 million years ago-505 million years ago) first period in the Paleozoic era, noted for the rapid development of many different life forms.
Cambrian Explosion of Life
Noun
rapid development of almost all major types (phyla) of organisms during the Cambrian time period.
carbon
Noun
chemical element with the symbol C, which forms the basis of all known life.
Noun
series of processes in which carbon (C) atoms circulate through Earth's land, ocean, atmosphere, and interior.
carbon dioxide
Noun
greenhouse gas produced by animals during respiration and used by plants during photosynthesis. Carbon dioxide is also the byproduct of burning fossil fuels.
Cenozoic
Noun
(65 million years ago-present) current geologic era
charged particle
Noun
molecule that has a positive or negative electric charge.
circulate
Verb
to move around, often in a pattern.
Noun
all weather conditions for a given location over a period of time.
Noun
visible mass of tiny water droplets or ice crystals in Earth's atmosphere.
compress
Verb
to press together in a smaller space.
condense
Verb
to turn from gas to liquid.
consist
Verb
consistent
Adjective
maintaining a steady, reliable quality.
continental crust
Noun
thick layer of Earth that sits beneath continents.
Noun
the extremely hot center of Earth, another planet, or a star.
craton
Noun
old, stable part of continental crust, made up of shields and platforms.
Noun
rocky outermost layer of Earth or other planet.
data
Plural Noun
(singular: datum) information collected during a scientific study.
decompose
Verb
dense
Adjective
having parts or molecules that are packed closely together.
diameter
Noun
dinosaur
Noun
very large, extinct reptile chiefly from the Mesozoic Era, 251 million to 65 million years ago.
dust
Noun
microscopic particles of rocks or minerals drifting in space. Also called cosmic dust or space dust.
Noun
our planet, the third from the Sun. The Earth is the only place in the known universe that supports life.
earthquake
Noun
the sudden shaking of Earth's crust caused by the release of energy along fault lines or from volcanic activity.
eject
Verb
to get rid of or throw out.
element
Noun
chemical that cannot be separated into simpler substances.
energy
Noun
eon
Noun
second-largest unit of geologic time, smaller than a supereon and larger than an era.
Noun
imaginary line around the Earth, another planet, or star running east-west, 0 degrees latitude.
Noun
act in which earth is worn away, often by water, wind, or ice.
essential
Adjective
Noun
process by which liquid water becomes water vapor.
Noun
process by which liquid water becomes water vapor.
evolve
Verb
to develop new characteristics based on adaptation and natural selection.
exosphere
Noun
outermost layer of Earth's atmosphere, beginning at an altitude of about 550 kilometers (341 miles) above the Earth's surface.
fault
Noun
a crack in the Earth's crust where there has been movement.
faulting
Noun
movement of rocks and tectonic plates beneath the Earth's surface.
flourish
Verb
to thrive or be successful.
Noun
Noun
remnant, impression, or trace of an ancient organism.
fossil fuel
Noun
coal, oil, or natural gas. Fossil fuels formed from the remains of ancient plants and animals.
freshwater
Noun
fungi
Plural Noun
(singular: fungus) organisms that survive by decomposing and absorbing nutrients in organic material such as soil or dead organisms.
gas
Noun
state of matter with no fixed shape that will fill any container uniformly. Gas molecules are in constant, random motion.
gas giant
Noun
one of the four enormous outermost planets in the solar system (Jupiter, Saturn, Neptune, Uranus), composed mostly of gases instead of rock. Also called a Jovian planet.
geoid
Noun
spheroid representation of the Earth that takes into account mean sea level and gravity.
geologic timeline
Noun
scale used by geologists used to divide the Earth's 4.6 billion year history into units of time.
geologist
Noun
person who studies the physical formations of the Earth.
Noun
natural hot spring that sometimes erupts with water or steam.
Noun
mass of ice that moves slowly over land.
granite
Noun
type of hard, igneous rock.
gravity
Noun
physical force by which objects attract, or pull toward, each other.
Hadean
Noun
(4.5 billion years ago-3.8 billion years ago) first eon in the Precambrian supereon. Also called the Pre-Archean.
Himalaya Mountains
Noun
mountain range between India and Nepal.
Homo sapiens
Noun
(200,000 years ago-present) species of primates (hominid) that only includes modern human beings.
Noun
all the Earth's water in the ground, on the surface, and in the air.
hygiene
Noun
science and methods of keeping clean and healthy.
Noun
Noun
thick layer of glacial ice that covers a large area of land.
Noun
rock formed by the cooling of magma or lava.
inner planet
Noun
one of the four rocky planets closes to the sun: Mercury, Venus, Earth, or Mars. Also called a terrestrial planet.
iron
Noun
chemical element with the symbol Fe.
Noun
body of land surrounded by water.
Noun
body of water surrounded by land.
Noun
specific natural feature on the Earth's surface.
Noun
the geographic features of a region.
Noun
distance north or south of the Equator, measured in degrees.
lava
Noun
molten rock, or magma, that erupts from volcanoes or fissures in the Earth's surface.
limestone
Noun
type of sedimentary rock mostly made of calcium carbonate from shells and skeletons of marine organisms.
liquid
Noun
state of matter with no fixed shape and molecules that remain loosely bound with each other.
Noun
outer, solid portion of the Earth. Also called the geosphere.
luminosity
Noun
energy emitted by a stellar object (such as a star or galaxy) per unit of time.
Noun
molten, or partially melted, rock beneath the Earth's surface.
magnetic field
Noun
area around and affected by a magnet or charged particle.
magnetosphere
Noun
teardrop-shaped area, with the flat area facing the sun, around the Earth controlled by the Earth's magnetic field.
Noun
middle layer of the Earth, made of mostly solid rock.
marble
Noun
type of metamorphic rock.
mass
Noun
unit of measurement (abbreviated m) determined by an object's resistance to change in the speed or direction of motion.
mesosphere
Noun
region in Earth's atmosphere between the stratosphere and the thermosphere, about 50-80 kilometers (31-50 miles) above the Earth's surface.
Mesozoic
Noun
(250 million years ago-65 million years ago) second era in the Phanerozoic eon. Also called the Age of Dinosaurs.
metamorphic rock
Noun
rock that has transformed its chemical qualities from igneous or sedimentary.
metamorphosis
Noun
complete change in form and structure from one part of the life cycle to the next, such as caterpillar to pupa, and pupa to butterfly.
mid-ocean ridge
Noun
underwater mountain range.
mineral
Noun
inorganic material that has a characteristic chemical composition and specific crystal structure.
molten
Adjective
solid material turned to liquid by heat.
Moon
Noun
Earth's only natural satellite.
nickel
Noun
chemical element with the symbol Ni.
Noun
substance an organism needs for energy, growth, and life.
oblate spheroid
Noun
shape of the Earth, which is larger around the Equator than at the poles.
Noun
large body of salt water that covers most of the Earth.
ocean current
Noun
continuous, predictable, directional movement of seawater.
oceanic crust
Noun
thin layer of the Earth that sits beneath ocean basins.
Noun
underwater fissure from which geothermally heated fluid is ejected.
orbit
Noun
path of one object around a more massive object.
organic
Adjective
composed of living or once-living material.
oxygen
Noun
chemical element with the symbol O, whose gas form is 21% of the Earth's atmosphere.
paleontologist
Noun
person who studies fossils and life from early geologic periods.
Paleozoic Era
Noun
about 541-252 million years ago.
particle
Noun
period
Noun
unit of geologic time, shorter than an era and larger than an epoch.
Phanerozoic
Noun
(542 million years ago-present) current eon in the geologic timeline, comprising the Paleozoic, Mesozoic, and Cenozoic eras.
Noun
process by which plants turn water, sunlight, and carbon dioxide into water, oxygen, and simple sugars.
Noun
large, spherical celestial body that regularly rotates around a star.
plant
Noun
organism that produces its own food through photosynthesis and whose cells have walls.
plate tectonics
Noun
movement and interaction of the Earth's plates.
pole
Noun
extreme north or south point of the Earth's axis.
Precambrian
Noun
(4.5 billion years ago-542 million years ago) first supereon in Earth's history.
Noun
all forms in which water falls to Earth from the atmosphere.
primitive
Adjective
Proterozoic
Noun
(2.5 billion years ago-542 million years ago) last eon in the Precambrian, noted for the development of bacteria and algae.
quartz
Noun
Quaternary
Noun
(2.5 million years ago-present) most recent period in geologic time.
radius
Noun
ray extending from the center of a circle or sphere to its surface or circumference.
Noun
rapid
Adjective
recycle
Verb
to clean or process in order to make suitable for reuse.
red giant
Noun
"main sequence" star with huge surface area, low surface temperature, and reddish color.
regulate
Verb
to determine and administer a set of rules for an activity.
revolution
Noun
orbit, or a complete journey of an object around a more massive object.
rift
Noun
break in the Earth's crust created by it spreading or splitting apart.
Noun
depression in the ground caused by the Earth's crust spreading apart.
Noun
horseshoe-shaped string of volcanoes and earthquake sites around edges of the Pacific Ocean.
Noun
large stream of flowing fresh water.
rock
Noun
natural substance composed of solid mineral matter.
Noun
processes that explain the relationship between the three rock types: igneous, sedimentary, and metamorphic. Any rock type can become any other.
Noun
object's complete turn around its own axis.
sand
Noun
small, loose grains of disintegrated rocks.
sandstone
Noun
common sedimentary rock formed by grains of sand compacted or cemented with material such as clay.
satellite
Noun
object that orbits around something else. Satellites can be natural, like moons, or made by people.
saturate
Verb
to fill one substance with as much of another substance as it can take.
Noun
period of the year distinguished by special climatic conditions.
Noun
rock formed from fragments of other rocks or the remains of plants or animals.
seismic
Adjective
having to do with earthquakes.
silicate
Noun
most common group of minerals, all of which include the elements silicon (Si) and oxygen (O).
silicate
Noun
most common group of minerals, all of which include the elements silicon (Si) and oxygen (O).
silicon
Noun
chemical element with the symbol Si.
soil
Noun
top layer of the Earth's surface where plants can grow.
solar radiation
Noun
light and heat from the sun.
solar system
Noun
the sun and the planets, asteroids, comets, and other bodies that orbit around it.
solar system
Noun
the sun and the planets, asteroids, comets, and other bodies that orbit around it.
solar wind
Noun
flow of charged particles, mainly protons and electrons, from the sun to the edge of the solar system.
spherical
Adjective
rounded and three-dimensional.
spring
Noun
small flow of water flowing naturally from an underground water source.
star
Noun
large ball of gas and plasma that radiates energy through nuclear fusion, such as the sun.
storm
Noun
severe weather indicating a disturbed state of the atmosphere resulting from uplifted air.
stratosphere
Noun
level of Earth's atmosphere, extending from 10 kilometers (6 miles) to 50 kilometers (31 miles) above the surface of the Earth.
subduct
Verb
to pull downward or beneath something.
Noun
star at the center of our solar system.
supereon
Noun
largest unit of geologic time. The Precambrian supereon lasted until 542 million years ago. We are currently in the second supereon, which has no name.
tectonic activity
Noun
movement of tectonic plates resulting in geologic activity such as volcanic eruptions and earthquakes.
tectonic plate
Noun
massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate.
Noun
degree of hotness or coldness measured by a thermometer with a numerical scale.
thermosphere
Noun
layer of the Earth's atmosphere located between 80 kilometers (50 miles) and 550 kilometers (341 miles) above the Earth's surface.
transportation
Noun
movement of people or goods from one place to another.
troposphere
Noun
lowest layer of the Earth's atmosphere, extending from the surface to about 16 kilometers (10 miles) above.
ultraviolet radiation
Noun
powerful light waves that are too short for humans to see, but can penetrate Earth's atmosphere. Ultraviolet is often shortened to UV.
universe
Noun
all known matter, energy, and space.
vapor
Noun
visible liquid suspended in the air, such as fog.
venture
Verb
to take a risky or dangerous opportunity.
volcanic eruption
Noun
activity that includes a discharge of gas, ash, or lava from a volcano.
Noun
an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.
volume
Noun
space an object occupies.
Noun
movement of water between atmosphere, land, and ocean.
Noun
the breaking down or dissolving of the Earth's surface rocks and minerals.
weather pattern
Noun
repeating or predictable changes in the Earth's atmosphere, such as winds, precipitation, and temperatures.
wind
Noun
movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.