angle: The space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet.
arc: A curve, often mapping out what appears to be part of a circle.
array: A broad and organized group of objects. Sometimes they are instruments placed in a systematic fashion to collect information in a coordinated way. Other times, an array can refer to things that are laid out or displayed in a way that can make a broad range of related things, such as colors, visible at once. The term can even apply to a range of options or choices.
astronomer: A scientist who works in the field of research that deals with celestial objects, space and the physical universe.
atmosphere: The envelope of gases surrounding Earth, another planet or a moon.
black hole: A region of space having a gravitational field so intense that no matter or radiation (including light) can escape.
cloud: A plume of molecules or particles, such as water droplets, that move under the action of an outside force, such as wind, radiation or water currents.
concave: A term for the shape of a surface that is rounded somewhat, like the inside of a bowl.
concrete: To be solid and real. (in construction) A simple, two-part building material. One part is made of sand or ground-up bits of rock. The other is made of cement, which hardens and helps bind the grains of material together.
convex: A surface that possesses a shape that is rounded outward.
cosmos: (adj. cosmic) A term that refers to the universe and everything within it.
degree: (in geometry) A unit of measurement for angles. Each degree equals one three-hundred-and-sixtieth of the circumference of a circle.
density: The measure of how condensed some object is, found by dividing its mass by its volume.
environment: The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of things in the vicinity of an item of interest).
focal point: The spot where several points converge or where a beam narrows to a point.
focus: (in physics) The point at which rays (of light or heat for example) converge sometimes with the aid of a lens. (In vision, verb, “to focus”) The action a person’s eyes take to adapt to light and distance, enabling them to see objects clearly.
galaxy: A group of stars — and usually invisible, mysterious dark matter — all held together by gravity. Giant galaxies, such as the Milky Way, often have more than 100 billion stars. The dimmest galaxies may have just a few thousand. Some galaxies also have gas and dust from which they make new stars.
gravity: The force that attracts anything with mass, or bulk, toward any other thing with mass. The more mass that something has, the greater its gravity.
hue: A color or shade of some color.
lens: (in biology) A transparent part of the eye behind the colored iris that focuses incoming light onto the light-absorbing membrane at the back of the eyeball. (in physics) A transparent material that can either focus or spread out parallel rays of light as they pass through it. (in optics) A curved piece of transparent material (such as glass) that bends incoming light in such a way as to focus it at a particular point in space. Or something, such as gravity, that can mimic some of the light bending attributes of a physical lens.
magnify: To increase in apparent size or number of something.
mass: A number that shows how much an object resists speeding up and slowing down — basically a measure of how much matter that object is made from.
microscope: An instrument used to view objects, like bacteria, or the single cells of plants or animals, that are too small to be visible to the unaided eye.
optical: An adjective that refers to light or vision.
particle: A minute amount of something.
peer: (noun) Someone who is an equal, based on age, education, status, training or some other features. (verb) To look into something, searching for details.
point: (in mathematics) A precise point in space that is so small that it has no size. It merely has an address.
prism: A triangular wedge of glass or another clear substance that can bend the components of white light into a rainbow-like succession of colored bands. (v.) To separate light into its component hues.
rainbow: An arc of color displayed across the sky during or just after a rain. It’s caused when water droplets in the atmosphere bend (or diffract) white sunlight into a number of its component hues: usually red, orange, yellow, green, blue, indigo and violet.
ray: (in mathematics) A line that has a defined endpoint on one side, but the other side continues on forever.
reflective: (v. reflect; n. reflection) Adjective that refers to the ability of something to reflect light strongly. Such objects can produce a strong bright glare when sunlight bounces off of them. Examples of reflective objects include a mirror, a smooth metal can, a car window, a glass bottle, ice, snow or the watery surface of a lake.
refract: (n. refraction) To change the direction of light (or any other wave) as it passes through some material. For example, the path of light leaving water and entering air will bend, making partially submerged objects to appear to bend at the water’s surface.
star: The basic building block from which galaxies are made. Stars develop when gravity compacts clouds of gas. When they become hot enough, stars will emit light and sometimes other forms of electromagnetic radiation. The sun is our closest star.
telescope: Usually a light-collecting instrument that makes distant objects appear nearer through the use of lenses or a combination of curved mirrors and lenses. Some, however, collect radio emissions (energy from a different portion of the electromagnetic spectrum) through a network of antennas.
warp: A change in the shape, usually due to some twisting or curving in a normally flat surface or plane. A piece of wet lumber may warp as it dries unevenly, causing it to bow or show a slight twist.
water vapor: Water in its gaseous state, capable of being suspended in the air.
wave: A disturbance or variation that travels through space and matter in a regular, oscillating fashion.
wavelength: The distance between one peak and the next in a series of waves, or the distance between one trough and the next. It’s also one of the “yardsticks” used to measure radiation. Visible light — which, like all electromagnetic radiation, travels in waves — includes wavelengths between about 380 nanometers (violet) and about 740 nanometers (red). Radiation with wavelengths shorter than visible light includes gamma rays, X-rays and ultraviolet light. Longer-wavelength radiation includes infrared light, microwaves and radio waves.