Accretion: The accumulation of material into a celestial body.
Acid: In chemistry, a substance that may have a sour taste, makes blue litmus paper turn red, and can react with a base to make salt. Common examples of acids include vinegar, lemon juice and stomach acid.
Albedo: The albedo of an object is the amount of light it reflects. A perfect reflector such as a mirror would have an albedo of 100, the Moon has an albedo of 7, and the Earth has an albedo of 36.
Anorthosite: The predominant rock of the lunar highlands.
Apogee: A point in the Moon's orbit where it is furthest from the Earth.
Arc Degree: A unit of angular measure in which there are 360 arc degrees in a full circle.
Astrobiology: The study of the origin, evolution, distribution, and future of life in the universe.
Astronomy: The scientific study of the universe, including the solar system, stars and galaxies.
Atmosphere: An envelope of mixed gases that surround a celestial body such as a planet, moon, or star. An atmosphere is held to the body by the body's gravity.
Atmospheric Pressure: A force over a given area that is caused by the weight of an atmosphere.
Axis: An imaginary line through the center of a planet or a satellite around which it rotates.
Basalt: A common volcanic rock usually grey to black and fine-grained due to rapid cooling of lava.
Base: A substance that may have a bitter taste, feels soapy, turns litmus blue, and can react with an acid to form salt. Common examples of bases are baking soda and ammonia.
Blood pressure: The pressure of blood on the walls of blood vessels.
Breccia: A rock made from mineral fragments cemented together by the heat of meteoroid impact.
Caldera: Created when the top of a volcano collapses into a crater.
Celestial: Having to do with the skies or visible heavens (the Sun, Moon, stars, and planetary bodies).
Composition: The chemical makeup of an object.
Compound: A substance made by combining two or more parts or elements; water is a chemical compound made from hydrogen and oxygen.
Condensation: A change of state from gas to liquid.
Coordinate System: A system used to identify locations on a graph or grid. Latitude and longitude are an example of a coordinate system.
Core: The central region of a planet or moon frequently made of different material than the surrounding regions (mantle and crust). Earth and the Moon are thought to have cores of iron and nickel.
Coronal Mass Ejection (CME): A huge magnetic bubble of plasma that erupts from the Sun and travels through space at a high speed.
Crater: A circular feature formed when impactors like meteorites smash into a surface. A crater can also from when the top of a volcano collapses into a caldera.
Crescent Moon: Moon phase with less than one-half of the side facing Earth illuminated.
Density: The compactness of matter or the number of particles per unit volume.
Diameter: The distance across a circle through its centre. Also, the distance through a sphere, measured through the centre of the sphere.
Diastolic: A measurement of the amount of pressure on the walls of blood vessels when the heart is at rest.
Diffraction: The bending of light as it passes through a small slit or opening. When we study the diffraction of sunlight, we see a rainbow of colours.
Eclipse: When our view of one object in the sky is blocked by either another object or the Earth's shadow.
Ejecta: Material blown out of a crater during an impact on the surface.
Ellipse: A conic section; the curve of intersection of a circular cone and a plane cutting completely through the cone.
Equatorial orbit: An orbit around the plane of the equator.
Erosion: The wearing away of a surface by natural process such as lava flow, bombardment, wind, water, or other mechanisms.
Escape Velocity: The speed an object must have in order to escape from another object's gravity.
First Quarter Moon: Moon phase between the New and Full Moon where exactly half of the side facing Earth is illuminated. This phase occurs approximately one week after New Moon.
Force: That which can change the momentum of a body. Numerically, the rate at which the body's momentum changes.
Full Moon: A phase of the Moon in which the entire side facing Earth is illuminated by sunlight.
Geologist: A scientist who studies the formation, structure, history and processes (internal and surface) that change Earth and other planetary bodies.
Geosynchronous orbit: An orbit that completes one revolution in the same amount of time it takes for the Earth to rotate once on its polar axis. An object in a geostationary orbit appears stationary (a fixed position in the sky) to ground observers.
Gibbous Moon: Moon phase when more than half (but not all) of the side facing Earth is illuminated.
Gravity: The natural force of attraction that exists between all bodies in the universe.
Humidity: The amount of water vapour in the air.
Hydroponic: The growth of plants using a water solution instead of soil.
Igneous Rock: Rock formed from cooled and hardened magma.
Impact Crater: A circular depression in the ground caused by meteoroids or asteroids hitting the surface of a planet.
Latitude: The angular distance north or south from the Earth's equator measured in degrees on the meridian of a point: equator being 0 degrees and the poles 90 degrees North and 90 degrees South.
Lava: Molten rock that erupts to Earth's surface through a volcano or a fissure.
Longitude: The angular distance east or west, between the meridian of a particular place on Earth and that of the Prime Meridian (located in Greenwich, England) expressed in degrees or time.
Lunar: Relating to the Moon
Magma: Melted rock located deep below the surface of a planet, such as Earth, or a moon.
Maria: Low areas on the Moon that appear dark and smooth. Maria are formed by ancient lava flows.
Mass: How much matter an object contains. It is not the same as weight, although an object's mass does help determine how much it will weigh.
Metamorphic Rock: Rock formed from pre-existing rocks as a result of intense heat, pressure or chemical processes.
Meteorite: A solid rocky or metallic object from space that passes through the Earth's atmosphere and lands on its surface. Meteorites are fragments of larger objects such as comets, asteroids, or planets.
Meteoroid: A small, solid body moving through space in orbit around the Sun.
Micrometeorites: Extremely small space rocks. They are so small that when they hit the Earth's atmosphere they burn up quickly.
Moon Phases: The monthly changes in the appearance of the Moon as seen from Earth. Phases are caused by the Moon's revolution around Earth.
New Moon: A phase of the Moon in which none of the sides facing Earth is illuminated by the Sun.
Orbit: The path of an object revolving around another object due to common gravity, e.g., the Moon around the Earth or planets moving around the Sun.
Parallel: Two lines running side by side at an equal distance apart. Railroad tracks run parallel to each other. Lines of constant latitude run parallel to the equator.
Payload: The cargo (scientific instruments, satellites, spacecraft, etc.) carried by a rocket.
Perigee: The point in the Moon's orbit where it is closest to the Earth.
pH: A scale from 1 - 14 that measures how acidic or basic (alkaline) a substance is.
Planet: Any of eight solid, nonluminous bodies revolving about the Sun.
Planetary Geology: The study of the processes and history associated with the solid, rocky objects of the solar system.
Polar axis: The axis of rotation of the Earth; also, an axis in the mounting of a telescope that is parallel to the Earth's axis.
Porphyritic: A geology term used to describe large crystals found in igneous rock.
Prism: A piece of transparent material that separates the colours of sunlight into a rainbow or spectrum.
Probe: A spacecraft, with no humans aboard, designed to study conditions on or near a planet.
Propulsion: The act of moving an object and maintaining its motion.
Pulse Rate: The number of times a heart beats per minute in a person's body.
Radiation: Radiation is energy that comes from a source and travels through some material or through space. Light,heat and sound are types of radiation. The most dangerous is space radiation. It is produced by the Sun and other stars in our galaxy and is composed of high energetic particles traveling at the speed of light. When these intensely ionizing particles come in contactwith human tissue it can result in cell damage.
Regolith: A powdery soil layer on the Moon's surface caused by bombardment by meteoroids.
Respiration rate: The number of breaths a person makes per minute.
Revolution: The motion of one body around another.
Rocket: A device propelled by ejection of matter, especially by the high velocity ejection of the gaseous combustion products produced by internal ignition of solid or liquid fuels.
Satellite: A satellite is an object that moves around a larger object. Earth is a satellite because it moves around the sun. The Moon is a satellite because it moves around Earth. Earth and the moon are called "natural” satellites. Satellites can also be 'man-made". For example, Communication and TV Satellites are man-made machines that orbit the Earth.
Sedimentary Rocks: A type of rock formed from hardened deposits of sediments.
Solar system: The system of the Sun and the planets, their satellites, the minor planets, comets, meteoroids, and other objects revolving around the Sun.
Sunspot: Dark patches on the Sun's surface caused by a temporary cooler region than the surrounding areas.
Solar Flares: Eruptions in the outer part of the Sun's atmosphere.
Space debris: Debris from satellites and space vehicles, as well as natural objects like meteoroids and planetary particles that travel through the Solar System.
Sublimation: The process of a solid returning directly to a gas without changing to a liquid first.
Space station: An orbiting space laboratory on which people could live and work for several years or more.
Systolic: the squeezing of the heart ventricles as they push blood along the arteries.
Spectroscope: An instrument that spreads light or other electromagnetic radiation into its component wavelengths (colours) for analysis.
Star: A self-luminous sphere of gas.
Tectonics: The process that forms planetary features such as continents, mountains, and faults by motion of sections (plates) of the Earth's crust driven by convection currents in the Earth's mantle.
Terrestrial: Relating to the Earth and its inhabitants and belonging to a class of planets that are Earth-like.
Trajectory: The path of a projectile or other moving body through space.
Third Quarter Moon: Moon phase between the Full and New Moon where exactly half of the side facing Earth is illuminated. This phase occurs approximately one week after a Full Moon.
Universe: The totality of all matter and radiation and the space occupied by same.
Velocity: A vector that denotes both the speed and direction a body is moving.
Volcano: An opening in the Earth's crust where molten lava, gases and ash are ejected.
Weight: The force with which the Earth's (or any celestial body's) gravity pulls down on something.
Waning: The Moon is said to be waning in its phase cycle as the amount of light reflected off the lunar surface towards the Earth decreases. This occurs as the cycle progresses from Full Moon to New Moon.
Waxing: The Moon is said to be waxing in its phase cycle as the amount of light reflected off the lunar surface towards the Earth increases. This occurs as the cycle progresses from New Moon to Full Moon.
Weathering: The action of elements in altering the colour, texture, composition, or form of exposed objects on the surface of a planet of Moon.
Zenith: Point directly above your head in the night sky.