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Astronomy Part 2
| Term | Definition |
|---|---|
| Photosphere | The luminous envelope of a star from which its light and heat radiate |
| Chromosphere | A reddish gaseous layer immediately above the photosphere of the sun or another star. |
| Corona | The rarefied gaseous envelope of the sun and other stars. |
| Solar Wind | The continuous flow of charged particles from the sun that permeates the solar system. |
| Sunspot | A spot or patch appearing from time to time on the sun's surface, appearing dark by contrast with its surroundings. |
| Prominence | An eruption of a flamelike tongue of relatively cool, high-density gas from the solar chromosphere into the corona where it can be seen during a solar eclipse or by observing strong spectral lines in its emission spectrum. |
| Solar Flare | A brief eruption of intense high-energy radiation from the sun's surface, associated with sunspots and causing electromagnetic disturbances on the earth, as with radio frequency communications and power line transmissions. |
| Nuclear Fusion | An atomic reaction that fuels stars. |
| Binary Star | A system of two stars in which one star revolves around the other or both revolve around a common center. |
| Light-Year | A unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 1012 km (nearly 6 trillion miles). |
| Apparent magnitude | The magnitude of a celestial object as it is actually measured from the earth. |
| Absolute magnitude | The magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs. |
| Main-sequence star | Any star that is fusing hydrogen in its core and has a stable balance of outward pressure from core nuclear fusion and gravitational forces pushing inward. |
| Red Giant | A very large star of high luminosity and low surface temperature. |
| Supergiant | A very large star that is even brighter than a giant, often despite being relatively cool. |
| Nova | A star showing a sudden large increase in brightness and then slowly returning to its original state over a few months. |
| Hertzsprung-Russel diagram | The graph showing the absolute magnitude plotted against the surface temperature for a group of stars. |
| Protostar | A contracting mass of gas that represents an early stage in the formation of a star, before nucleosynthesis has begun. |
| Supernova | A star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass. |
| White dwarf | A small very dense star that is typically the size of a planet. |
| Neutron Star | A celestial object of very small radius (typically 18 miles/30 km) and very high density, composed predominantly of closely packed neutrons |
| Black Hole | A region of space having a gravitational field so intense that no matter or radiation can escape. |
| Galaxy | A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction. |
| Big Bang Theory | The prevailing cosmological model for the universe from the earliest known periods through its subsequent large-scale evolution. |
Created by:
madisonbarden
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