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Celestial Terms
Mr. Wills Astronomy Words For Chapter 2
| term | definition |
|---|---|
| Universal Nebula/Interstellar Medium | the universe before stars began to form |
| Nebula | massive cloud of dust that may condense to form stars. pl nebulae. This is the first stage of star formation |
| Protostar | hot contracting cloud (planet) of dust and gases. First visible light appears in cloud. If the star is not hot enough it may not become a star but a brown dwarf like Jupiter or Saturn. |
| Massive stars | stars bigger (6-10 more mass not diameter) than our sun that will eventually have an iron core before it explodes or just dies |
| Medium stars: | stars in which nuclear fusion is already occurring. (hydrogen turns to helium) These stars are usually yellow in color. ex. Our sun. |
| Giant stars: | Stage between medium sized and red giant star usually orange in color. |
| Supergiant Stars: | very large and cool stars that have helium core. These stars are beginning to die and will become a supernova and or white dwarf |
| White dwarfs: | the remnants of a dying star. They are very small and heavy. Nuclear reactions are still occurring but will soon stop. As the star dies it will become a red dwarf and then a black dwarf (dead-no light). |
| Neutron stars/pulsars: | very small dense remains of stars that still give off radio waves. These waves were once thought to be messages from aliens. |
| Quasars: | very distant objects believed to be stars that only give off X-rays and radio waves. |
| Black Holes: | extremely dense objects that are so massive there gravity will not allow matter or light escape from them that are formed by stars, galaxies and perhaps the universe collapsing on its self. |
| Nova: | the nuclear explosion of the gases between stars in a binary system. pl novae |
| Supernova: | the explosion of a star. The light from this star can sometimes be seen during the day and is short lived; weeks to months. |
| Binary Stars | two stars held in proximity by gravity. |
| Cluster: | group of stars that look to be close together from earth |
| Constellation | group of star that form a pattern as seen from earth. |
| Galaxy: | a huge collection of stars held together by gravity. |
| Spiral galaxy | a young galaxy that is spiral in shape, like the galaxy we are in the milky-way |
| Elliptical galaxy: | an older galaxy in which the star seem to be closer together in the shape of an egg. |
| Irregular galaxy: | a galaxy that does not have a spiral or elliptical shape. |
| Universe: | the sum of all the matter in existence. Some scientists believe there is a multiverse (many universes). |
| Characteristics of stars: | Stars differ in many features, including size, mass, color, temperature, and brightness |
| Spectroscope: | device for used for seeing the colors produced by the light of a star. These colors are used to identify the elements that are burning in the star. |
| Spectrum: | colors produced by visible light when separated by a prism |
| Red shift: | a color change in the spectrum produced by objects that are moving away from earth. Pg 59 |
| Blue shift | a color change in the spectrum produced by objects that are moving closer from earth. |
| Doppler Effect: | apparent change in the wavelengths of light or sound that caused by moving objects. Pg 60 |
| Gravity: | the force of attraction between all matter |
| Apparent magnitude(brightness): | the brightness of a star as seen from earth. It is affected by its size, surface temperature and distance from earth. |
| Absolute magnitude(brightness): | the actual brightness of a star. |
| Pulsating variable star | stars brightness that changes on a cycle. The north star(every four days) |
| Hertzprung- Russell diagram | diagram shows the relationship between temperature and magnitude |
| Main sequence star: | forms a diagonal line in the Hertzsprung-Russell diagram. 90% of stars are main sequence. |
| Parallax: | method of finding the actual distance to a star |
| Nuclear Fusion: | process of combining the nucleus of atoms to create larger atoms and new elements. Takes place at high temperature and gravity. |
| Corona: | outermost layer of the suns atmosphere |
| Chromosphere: | middle layer of the suns atmosphere this is where the solar flares occur(and prominences) |
| Photosphere: | the innermost atmosphere of the sun. The surface of the sun. |
| Core: | The center of the sun where nuclear fusion occurs |
| Prominence: | a solor explosion of gases that look like an arch on the sun |
| Solar flare: | solar storm that sends out a huge flame from the surface of the sun |
| Solar wind: | continuous stream of high eneryg particles that are realeased into space from the sun |
| Sunspot: | cooler(still very hot) portion of the suns surface |
| Axis: | imaginary verticle line through the center of the sun that the sun gases spin around. |
| Planetary nebula : | reamains of the gases of a burned out red giant star. A white dwarf is usually found at its center pg. 81 |
| Open Universe: | universe that is believed will expand forever |
| Closed Universe | universe that is believe to expand and contract due to gravity crating multiple big bangs |
| Big Bang Theory | theoretical event in which the universe began to expand with an explosion of concentrated matter, about 10-15 billion years ago and has been expanding ever since. |
| ertyertywrty | rqwwertwert |
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