Planet Earth and Beyond Glossary

  • altitude: height above sea level

  • atmosphere: the layer of gases surrounding the Earth and held in place by gravity

  • aurora: a natural phenomenon whereby charged particles from the Sun interact with atmospheric particles; this is observed as bright, coloured "lights" in the sky, mostly in polar regions

  • bellows: a device that produces a stream of air when it is squeezed

  • biosphere: the part of the Earth and its atmosphere in which living organisms exist or that is capable of supporting life

  • black dwarf: a white dwarf that has sufficiently cooled and used up all of its energy so that it no longer emits any heat or light; the star is now dead and will remain like this

  • blast furnace: used in the extraction of iron from iron-ore, a high temperature oven in the form of a tower into which compressed air can be introduced from below

  • bloomery: a type of oven used for purifying iron from iron ore

  • brittle: material that is hard, but can break or shatter easily

  • carbon dioxide: a gas with the chemical formula CO2

  • cementation: the process of solidifying sediments by chemical compounds acting as glue

  • CFCs: chlorofluorocarbons, are molecules which release chlorine atoms due to solar radiation in the stratosphere

  • climate change: a significant and lasting change in weather patterns; if there is a change in the world's weather patterns, it is global climate change

  • compaction: an increase in the density of something

  • composition: what makes up a substance or a mixture

  • constellation: a group of stars in a recognisable pattern

  • continental crust: the thick part of the Earth's crust that forms the continents

  • cooling: lowering the temperature

  • core: innermost layer of the Earth

  • crust: the thin, solid, outermost layer of the Earth

  • cycle: a continuous process where the last step feeds into the first again

  • density separation: a separation method where the differing densities of particles are used to separate them out

  • deposition: the process where sediments, rocks and and sand are deposited (laid down) by wind or water

  • electromagnets: a soft metal core made into a temporary magnet by passing current through a coil surrounding it

  • erosion: the breakdown and movement of the Earth's surface by natural agents like wind and water

  • evolution: (of stars) the changes a star undergoes as it is born, lives and dies

  • excavation: the process of removing rock containing ore from the surrounding rock

  • exosphere: considered part of outer space; the uppermost layer directly above the thermosphere, where the gases thin out and the atmosphere merges with space

  • exploration: the process of finding out where profitable mineral deposits are located

  • extrusive rock: igneous rock which forms when magma flows out onto the surface of the Earth as lava

  • flotation: a separation method by which hydrophobic particles are separated from hydrophilic particles by blowing air through the mixture

  • geochemical methods: exploration methods using knowledge of geology and the chemistry of minerals

  • geophysical methods: exploration methods using knowledge of geology and the physical properties of minerals

  • geosphere: the core, mantle and crust of the Earth

  • global warming: a gradual increase in the temperature of the Earth's atmosphere

  • greenhouse effect: the trapping of the Sun's energy in the lower part of the atmosphere due to the presence of greenhouse gases

  • greenhouse gases: gases like water vapour, carbon dioxide and methane, which let through sunlight but reflect ultraviolet radiation

  • hydrosphere: all the water, in all its forms, found on Earth

  • igneous rock: a rock type formed by magma or lava

  • International Space Station: a multinational space station, used for research purposes, which orbits the Earth at 370 km above the surface

  • intrusive rock: igneous rock which forms from magma deep below the surface of the Earth

  • ionosphere: the region mainly in the thermosphere where high energy light (UV light) can cause atoms, molecules or substances to form an ion or ions, typically by removing one or more electrons

  • lithosphere: the outer part of the Earth consisting of the crust and the upper part of the mantle; it includes all rock, soil and minerals found on Earth

  • magnetic separation: a separation method based on the magnetic properties of the mixture

  • main sequence star: a star that has hydrogen undergoing nuclear fusion reactions into helium in its core

  • mantle: the middle layer of the Earth

  • melting: the change from a solid to a liquid as a result of heating

  • mesosphere: the layer of the Earth's atmosphere above the stratosphere, extending to about 80 km above the surface of the Earth

  • metamorphic rock: a rock type formed through the transformation, or metamorphosis, of other rock types

  • meteor: a small body of mass entering the Earth's atmosphere from space which emits light as a result of friction and heat, and appears as a streak of light

  • meteorite: a meteor which has collided with the Earth

  • methane: a gas with the chemical formula CH4

  • mineral: natural compounds formed through geological processes; the term "mineral" includes both a material's chemical composition and its structure

  • nebula: a vast cloud of gas and dust in space

  • neutron star: an extremely dense star made of neutrons about the size of a small town in diameter

  • northern lights: the aurora in the northern hemisphere; also called aurora borealis

  • nuclear fusion: process in which two light nuclei of atoms combine to produce a heavier single nucleus, with a total mass slightly less than that of the total initial material, the difference in mass is radiated as energy

  • oceanic crust: the thinner part of the Earth's crust that underlies the oceans

  • ore: a naturally occurring solid material from which a metal or valuable mineral can be extracted

  • overburden: the layer of rock or sand overlying a mineral deposit

  • ozone: a gas molecule found in the stratosphere consisting of 3 oxygen atoms (O3)

  • panning: a separation method based on the density gradient of the mixture

  • PGM: platinum group metals, which includes ruthenium, rhodium, palladium, osmium, iridium and platinum, and are elements on the Periodic Table

  • planetary nebula: a cloud of gas (the remains of the original star's atmosphere) surrounding an old star; these have a confusing name because they actually have nothing to do with planets at all

  • protostar: a contracting mass of gas that will become a star once it is hot enough for nuclear fusion to start

  • radiation: the transfer of energy from a source that does not require physical contact or movement of particles

  • red giant star: an old, bright, very big, cool star; main sequence stars evolve to become red giant stars once the hydrogen in their cores has been depleted

  • rehabilitation: an area is restored to certain specifications, for example an area that has been mined is rehabilitated by planting trees or grass

  • remote sensing: gathering information from a distance, without making physical contact

  • sediment: particles, for example those that arise from erosion and weathering, settle in layers

  • sedimentary rock: a rock type formed from solidifying sediment

  • sedimentation: the deposition and solidification of sediment

  • size separation: a separation method based on the size of the particles

  • slag: the waste product extracted from a blast furnace after extracting iron from iron-ore

  • slurry: a watery mixture of solids and liquids

  • solidify: becoming a solid

  • southern lights: the aurora in the southern hemisphere; also called aurora australis

  • stellar wind: a flow of neutral or charged gas ejected from a star (the solar wind refers specifically to the stellar wind of our Sun)

  • stellar: of stars, such as a stellar nebula

  • stratosphere: the layer of the Earth's atmosphere above the troposphere, extending to about 50 km above the surface of the Earth

  • supernova: an explosion in a high mass star where the outer layers of the star are flung off into space

  • temperature gradient: how much the temperature changes as height above sea level (altitude) increases

  • thermosphere: the layer of the Earth's atmosphere above the mesosphere, extending from about 480 to 600 km above the surface of the Earth

  • topsoil: the upper surface of the Earth consisting of a layer of vegetation and soil

  • troposphere: the lowest layer of the Earth's atmosphere, extending from sea level to about 9-17 km

  • water vapour: a gas with the chemical formula H2O; water in its gaseous form

  • weathering: the wearing away of rocks as a result of exposure to wind, water and ice

  • white dwarf: a small hot, very dense star that is the size of a planet