| A | B |
|---|
| Electromagnetic Spectrum | a way of organizing all types of light waves according to frequency |
| Galaxy Cluster | a system of galaxies containing from several to thousands of member galaxies |
| Doppler Effect | describes how wavelength changes as the source moves toward or away from the observer |
| Sun | an average sized star that is the source of all energy on our planet |
| Apparent Magnitude | the brightness of a star as viewed from Earth |
| Galaxy | a collection of stars, dust, and gasses held together by gravity |
| Milky Way | our galaxy |
| Nebula | a cloud of dust and gases in which stars form |
| Protostar | a developing star not yet hot enough to perform nuclear fusion |
| Main Sequence | where stars spend 90% of their lives |
| Red Giant | a large, cool, bright star that is found in the upper right corner of the HR diagram |
| Super Giant | what very large stars become after they run out of hydrogen fuel |
| Supernova | an exploding star that increases in brightness several times |
| Black Hole | a massive star that has collapsed to such a small volume that its gravity prevents the escape of everything, including light |
| Neutron Star | a star of extremely high density composed entirely of neutrons |
| Pulsar | a spinning neutron star |
| Big Bang | theory that explains the origin of the universe |
| Cosmic Background Radiation | low frequency EM radiation that is thought to be leftover from the Big Bang |
| Reflecting | a telescopes that uses large mirrors to focus visible light into an image |
| Gamma Ray | highest frequency EM radiation; used in chemotherapy |
| X Ray | invisible EM radiation that is used in medical imaging |
| Visible Light | all the color of the rainbow - ROY G BIV! |
| Wavelength | distance between two adjacent wave crests |
| Frequency | the number of wave crests that pass a certain point in a certain time |
| Period | the time it takes for a wave to complete one wave cycle; the inverse of the frequency |
| Amplitude | how "big" a wave is; distance from midpoint to a wave crest or trough |
| Binary Star | one of two stars revolving around a common center of mass because of their mutual gravitational attraction |
| Solar Flare | a sudden and tremendous explosion in the solar atmosphere |
| Absorption Spectrum | also known as a dark-line spectrum; created when white light is passed through a cool gas |
| Emission Spectrum | also known as a bright-line spectrum; created by a hot glowing gas |
| Continuous Spectrum | spectrum that shows all the colors of the rainbow; created when white light is passed through a prism |
| Hertzsprung-Russell Diagram | diagram that shows the relationship between stars' temperature and brightness |
| Microwave | low frequency, invisible EM radiation; used for communications and cooking |
| Infrared Radiation | EM radiation just outside the visible range; heat energy |
| Core | layer of the sun in which nuclear fusion occurs |
| Radiation Zone | layer of the sun in which energy moves out from the core |
| Convection Zone | layer of the sun in which matter moves in density cycles |
| Photosphere | layer of the sun that we can see; brightest layer |
| Chromosphere | layer of the sun only visible during a solar eclipse; named for the red color that helium produces |
| Solar Prominence | a concentration of gases above the solar surface that appears as a bright archlike structure |
| Corona | the weak outer layer of the solar atmosphere; only visible during a solar eclipse |
| Sunspot | a large dark spot on the sun; cool relative to the surrounding bright areas; caused by interference of convection cycles by sun's magnetic field |
| Granulation | speckled appearance of the sun's photosphere; caused by convection currents |
| Aurora Borealis | colored light show caused by charged particles in the solar wind interacting with atoms in the Earth's atmosphere |
| Solar Wind | streams of charged particles ejected at high speeds from the solar corona |
| Solar Eclipse | occurs when the moon moves in a line directly between Earth and the sun, casting a shadow on the Earth |
