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Galaxies
Vocabulary
Term | Definition |
---|---|
Constellations | An apparent group of stars originally named for mythical characters. |
Parallax | The slight shifting in apparent position of a nearby star due to the orbital motion of Earth. |
Light-Year | The distance light travels in one year. |
Apparent Magnitude | A star's brightness as it appears from Earth. |
Absolute Magnitude | How bright a star actually is. |
Main-Sequence Star | A star that falls into the main-sequence category on the H-R diagram. |
Red Giants | A large, cool star of high luminosity |
Super giant | A very large, very bright red giant star |
Cepheid Variables | A star whose brightness varies periodically because it expands and contracts (pulsating). |
Nebulae | Clouds of gas and dust in space |
Protostar | A developing star not yet hot enough to engage in nuclear fusion. |
Supernova | An exploding star that increases in brightness many thousands of times |
White Dwarf | A star that has exhausted most or all of its nuclear fuel and has collapsed to a very small size. |
Neutron Stars | Stars that are smaller and more massive than white dwarfs, thought to be the remnants of supernova events. |
Pulsar | A spinning neutron star that appears to give off pulses of radio waves. |
Black Hole | Dense objects with gravity so strong that not even light can escape the surface. |
Spiral Galaxies | Disk-shaped galaxies with a greater concentration of stars near their nuclei. |
Elliptical Galaxies | Galaxies that range in shape from round to oval. |
Irregular Galaxies | Galaxies with irregular shapes. |
Galaxy Clusters | Galaxies that are grouped together. |