| A | B |
|---|
| radiative zone | region surrounding the core of the sun, in which energy is transferred in the form of waves |
| convective zone | region around the sun's radative zone in which moving gases transfer energy |
| photosphere | the innermost layer of the solar atmosphere |
| chromosphere | the thin layer of the sun's atmosphere that lies above the photosphere & glows with a reddish light |
| corona | the outermost layer of the sun's atmosphere |
| sunspots | cool dark area of gas within the photosphere caused by powerful magnetic fields |
| prominence | cloud of glowing gases that arches high above the sun's surface |
| solar flare | sudden, violent eruption of electrically charged atomic particles from the sun's surface |
| solar wind | electrically charged atomic particles that stream out into space through holes in the sun's corona |
| aurora | sheets of colored light produced by a magnetic storm in Earth's upper atmosphere |
| astronomical unit | average distance between Earth & the sun; about 150 million km |
| geocentric model | Earth centered model of the solar system |
| heliocentric model | sun centered model of the solar system |
| ellipse | oval whose shape is determined by two points within the figure |
| asteroid | chunk of rock that orbits the sun |
| meteoroid | small bit of rock or metal moving through the solar system left by a comet or produced by a collision between asteroids |
| meteor | meteoroid that enters Earth's atmosphere |
| meteorite | meteor or part of a meteor left after it hits Earth's surface |
| comet | body of rock, dust,methane, ammonia & ice that revolves around the sun in a long ellipitcal orbit |
| Oort cloud | spherical cloud of dust & ice that surrounds the solar system & is thought to be the place of origin of comets |
| rocky terrestrial planets | any one of the 4 planets closest to the sun with properties similar to those of Earth |
| Jovian planets | any one of the first four outer planets with properties similar to those of Jupiter |
| maria | dark areas of dry, solidified lava on the moon that are smooth & reflect little light |
| rilles | long deep channels that run through the maria on the moon |
| solar eclipse | passing of the moon between Earth & the sun during which the shadow of the moon falls on Earth |
| lunar eclipse | passing of Earth between the moon & the sun during which Earth's shadow falls on the lighted half of the moon |
| new moon | phase of the moon during which the side of the moon facing Earth is unlighted |
| full moon | phase of the moon during which the entire half of the moon facing Earth is visible |
| waning | describing the phase of the moon during which the size of its visible portion is decreasing |
| waxing | describing the phase of the moon during which the size of its visible portion is increasing |
