| A | B |
|---|
| nebula | large, dense cloud of Hydrogen gas that creates new stars |
| planet | large, spherical celestial body moving in an elliptical orbit around a star. |
| satellite | natural or artificial body that orbits a planet |
| galaxy | system of millions or billions of stars, together with gas and dust, held together by gravitational attraction. |
| dark_energy | ***theoretical energy causing the universe to accelerate its separation |
| dark_matter | ***theoretical substance increasing the gravitation forces holding galaxies together |
| supernova | explosion of a large star, producing heavy elements of the periodic table |
| white_dwarf | ***remnants of a medium sized star at the end of its life cycle |
| neutron | star remnant, made of neutrons; formed by the collapse of a giant star |
| pulsar | neutron star that emits rapid and periodic pulses of radiation |
| galaxy | system of millions or billions of stars, together with gas and dust, held together by gravitational attraction |
| elliptical | galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile |
| spiral | galaxy in which the stars and gas clouds are concentrated mainly in one or more spiral arms. |
| irregular | galaxies with no discernible shape |
| big_bang | ***explosive release of energy and matter that first formed our universe almost 14 billion years ago |
| constellation | group of stars forming a pattern that is traditionally named after its apparent form or identified with a mythological figure |
| photosphere | visible outer layer of a star, |
| core | center of the sun where nuclear fusion occurs |
| chromosphere | reddish gaseous layer immediately above the photosphere of the sun |
| corona | rarefied gaseous envelope of a sun's corona; is normally visible only during a total solar eclipse |
| sunspot | dark patch appearing from time to time on the sun's surface; appears dark by contrast with its surroundings. |
| CME | coronal mass ejection |
| photon | electromagnetic energy, regarded as a discrete particle having zero mass & no electric charge |
| solar_wind | ***stream of high-speed, ionized particles ejected primarily from the sun's corona |
| red_giant | life cycle stage for a star where helium begins to fuse and the sun's curface expands |
