PTE

a system of two stars that orbit their shared center of mass

a body that orbits the Sun, is nearly round because of its own gravity, has not cleared its orbital neighborhood, and is not a satellite

the region around a star where a planet could have liquid water on its surface under suitable atmospheric conditions

located or occurring in the space between stars

the amount of energy a celestial object emits as radiation per unit of time

a small piece of rock or metal moving through space

a condition of near weightlessness, such as that experienced by objects falling together in an orbiting spacecraft

a cloud of gas and dust in space

the study of objects in space by detecting the radio waves they emit

a star in a later life stage whose outer layers have expanded and become cooler

a shift in observed light toward longer wavelengths compared with the wavelengths at emission

a group of stars that formed together or are held together by gravity

a powerful stellar explosion that produces a large temporary increase in brightness

a state in which tidal effects make a body's rotation match its orbital motion so the same side faces its companion

the apparent passage of a smaller celestial body across the face of a larger one as seen by an observer

a compact stellar remnant that no longer sustains nuclear fusion in its core and gradually cools

the inward component of net force that changes an object's direction in circular motion

the spreading and pattern formation of waves around obstacles or after passing through openings

a process in which light atomic nuclei combine to form heavier nuclei

a strong oscillating response when a system is driven near one of its natural frequencies

a property describing how readily a material conducts heat under a temperature difference

a framework of connected members, often arranged in triangles, used to carry structural loads

the pressure exerted by vapor in equilibrium with its liquid or solid form at a specified temperature

a measure of how strongly a fluid resists flowing

having substantial resistance to flow

the energy barrier associated with the pathway by which a chemical reaction proceeds

a sensitive laboratory balance designed to measure small differences in mass accurately

having water as the solvent or describing a substance dissolved in water

to increase the rate of a chemical reaction by acting as a catalyst