All known planets have metal cores. Even the gas giants of our solar system, such as Jupiter and Saturn, have iron and nickel at their cores.
process by which a substance grows by the collection and clustering of different parts.
mixture of two or more metals.
process of studying a problem or situation, identifying its characteristics and how they are related.
material remains of a culture, such as tools, clothing, or food.
irregularly shaped planetary body, ranging from 6 meters (20 feet) to 933 kilometers (580 miles) in diameter, orbiting the sun between Mars and Jupiter.
(atm) unit of measurement equal to air pressure at sea level, about 14.7 pounds per square inch. Also called standard atmospheric pressure.
the basic unit of an element, composed of three major parts: electrons, protons, and neutrons.
single axis or line around which a body rotates or spins.
seismic wave that travels through the interior of the Earth.
to exist on the edge of a boundary.
line separating geographical areas.
fragile or easily broken.
seismic boundary between Earth's liquid outer core and solid inner core.
capable of floating.
type of stony meteorite containing hardened droplets, called chondrules, of silicate minerals.
to mix vigorously or violently.
condition or situation.
arrangement of the parts of a work or structure in relation to each other and to the whole.
instance of being pressed together or forced into less space.
items gathered closely together in one place.
to transmit, transport, or carry.
puzzling question or problem.
transfer of heat by the movement of the heated parts of a liquid or gas.
movement of a fluid from a cool area to a warm area.
the extremely hot center of Earth, another planet, or a star.
force that explains the paths of objects on rotating bodies.
rocky outermost layer of Earth or other planet.
type of mineral that is clear and, when viewed under a microscope, has a repeating pattern of atoms and molecules.
temperature at which a ferromagnetic material loses its ferromagnetism—its ability to possess magnetism in the absence of a magnetic field.
steady, predictable flow of fluid within a larger body of that fluid.
(singular: datum) information collected during a scientific study.
to put out of shape or distort.
having parts or molecules that are packed closely together.
device that compresses a test substance to up to 6 million atmospheres of pressure.
to break up or disintegrate.
unique or identifiable.
the sudden shaking of Earth's crust caused by the release of energy along fault lines or from volcanic activity.
set of physical phenomena associated with the presence and flow of electric charge.
chemical that cannot be separated into simpler substances.
imaginary line around the Earth, another planet, or star running east-west, 0 degrees latitude.
on the outside or outdoors.
to constantly change back and forth.
material that is able to flow and change shape.
temperature at which liquid becomes solid; the freezing point of water is 0 degrees Celsius (32 degrees Fahrenheit).
rate of occurrence, or the number of things happening in a specific area over specific time period.
device used for heating by burning a fuel, such as wood or coal.
process by which a celestial body generates a magnetic field.
having to do with the physical formations of the Earth.
change in a celestial body's magnetic field so that the magnetic North and South Poles are switched.
gradual change in temperature from the Earth's core (hot) to its crust (cool), about 25° Celsus per kilometer of depth (1° Fahrenheit per 70 feet of depth).
process of a glacier moving and changing the landscape.
to move toward or be attracted to something.
chemical substance with a specific gravity of at least 5.0.
half of a sphere, or ball-shaped object.
intensely hot region deep within the Earth that rises to just underneath the surface. Some hot spots produce volcanoes.
deepest layer of the Earth, beneath the outer core.
oddly crystallized structure at the heart of our planet, with iron crystals oriented east-west instead of north-south (as with the inner core).
to explain or understand the meaning of something.
chemical element with the symbol Fe.
(~4 billion years ago) point in Earth's planetary formation when the temperature reached the melting point of iron and heavy elements (mostly iron and nickel) gravitated toward the center of the planet.
(acronym for light amplification by stimulated emission of radiation) an instrument that emits a thin beam of light that does not fade over long distances.
outer, solid portion of the Earth. Also called the geosphere.
(large low shear velocity province) seismically anomalous region at the deepest part of Earth's mantle. Also called a superplume or thermo-chemical pile.
able to produce a force field that can attract or repel certain substances, usually metals (magnets).
area around and affected by a magnet or charged particle.
direction that all compass needles point.
flexible and capable of reforming itself without breaking when under stress.
middle layer of the Earth, made of mostly solid rock.
temperature at which a solid turns to liquid.
type of rock that has crashed into Earth from outside the atmosphere.
inorganic material that has a characteristic chemical composition and specific crystal structure.
representation of a process, concept, or system, often created with a computer program.
solid material turned to liquid by heat.
nickel-iron alloys that form Earth's core.
to move in a circular pattern around a more massive object.
relative positions of specific atoms or molecules in a chemical compound.
liquid, iron-nickel layer of the Earth between the solid inner core and lower mantle.
layer in the atmosphere containing the gas ozone, which absorbs most of the sun's ultraviolet radiation.
to look quickly or from a secret location.
very important or crucial point.
large, spherical celestial body that regularly rotates around a star.
process of separating different layers of a planetary body by chemical and physical mechanisms.
state of matter with no fixed shape and molecules separated into ions and electrons.
valuable metal, such as gold, silver, or platinum.
to choose or prioritize.
first or most important.
seismic shock wave that represents longitudinal motion. Also called a primary wave or pressure wave.
extreme or drastic.
transformation of an unstable atomic nucleus into a lighter one, in which radiation is released in the form of alpha particles, beta particles, gamma rays, and other particles. Also called radioactivity.
ray extending from the center of a circle or sphere to its surface or circumference.
natural substance composed of solid mineral matter.
object's complete turn around its own axis.
shock wave of force or pressure that travels through the Earth.
moving, measurable change in pressure and density of a material.
material that has a chemical affinity for iron.
most common group of minerals, all of which include the elements silicon (Si) and oxygen (O).
to create an image, representation, or model of something.
the sun and the planets, asteroids, comets, and other bodies that orbit around it.
flow of charged particles, mainly protons and electrons, from the sun to the edge of the solar system.
to make solid.
knowledgeable or complex.
series of changes affecting natural and human activity on Earth's surface.
series of changes affecting natural and human activity on Earth's surface.
to consider or guess.
area where one tectonic plate slides under another.
seismic shock wave that represents perpendicular motion. Also called a secondary wave or shear wave.
massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate.
degree of hotness or coldness measured by a thermometer with a numerical scale.
to pass along information or communicate.
powerful light waves that are too short for humans to see, but can penetrate Earth's atmosphere. Ultraviolet is often shortened to UV.
exactly the same in some way.
huge and spread out.
measurement of the rate and direction of change in the position of an object.
measure of the resistance of a fluid to a force or disturbance.
activity that includes a discharge of gas, ash, or lava from a volcano.
upward movement of molten material from within the Earth to the surface, where it cools and hardens.
radiation in the electromagnetic spectrum with a very short wavelength and very high energy.