| A | B |
|---|
| geologic time | the time of the physical formation and development of earth |
| half life | the time it takes for half the mass of a given amount of radioactive element to decay into its daughter elements |
| isotope | atoms of an element that have the same atomic number but different atomic mass numbers |
| Law of Superposition | principle that a sedimentary rock layer is older than the layers above it and younger than the layers below it |
| radioactive decay | the process through which an atom loses protons or neutrons |
| radiometric dating | a method of determining the age of an object based on the amount of a particular isotope contained within it |
| Doppler Effect | the apparent shift in the wavelength of energy, such as a sound wave or light wave, emitted by a source moving away from or toward an observer |
| electromagnetic spectrum | the complete range of wavelengths of radiation |
| frequency | the number of wavelengths that pass a reference point in a given amount of time |
| revolution | the movement of a planet around the sun |
| rotation | the spinning of a planet on its axis |
| stellar evolution | the process a star undergoes; a sequence of changes in its lifetime |
| wavelength | the distance between any two corresponding points on successive waves |
