Across
- 2. a region of space having a gravitational field so intense that no matter or radiation can escape
- 4. a large-scale structure in the universe consisting of hundreds to thousands of galaxies bound together by gravity.
- 5. a type of galaxy characterized by a flat, rotating disk of stars, gas, and dust, with a central concentration of stars called a bulge, and prominent spiral arms extending outwards from the center.
- 9. relatively young, metal-rich stars found in the disk of a galaxy, including the Milky Way's spiral arms.
- 13. a system of two stars in which one star revolves around the other or both revolve around a common center.
- 14. a galaxy that doesn't fit neatly into the categories of spiral or elliptical galaxies.
- 16. a cluster of about 50 galaxies, including our own Milky Way, that are gravitationally bound to each other.
- 18. a variable star having a regular cycle of brightness with a frequency related to its luminosity, so allowing estimation of its distance from the earth.
- 20. a continuous stream of plasma (ionized gas) that flows outward from the Sun's corona.
- 21. the central region of the Milky Way galaxy, a location around 26,000 light-years away from Earth.
- 22. a gravitationally bound collection of galaxies, containing typically less than 50 galaxies, each with a luminosity similar to or greater than the Milky Way.
- 23. the angular amount of parallax in a particular case, especially that of a star viewed from different points in the earth's orbit.
- 24. a cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter.
- 25. a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
- 27. a series of star types to which most stars belong, represented on a Hertzsprung–Russell diagram as a continuous band extending from the upper left (hot, bright stars) to the lower right (cool, dim stars).
- 28. a stream of incandescent gas projecting above the sun's chromosphere.
Down
- 1. a celestial object of very small radius (typically 18 miles/30 km) and very high density, composed predominantly of closely packed neutrons. Neutron stars are thought to form by the gravitational collapse of the remnant of a massive star after a supernova explosion, provided that the star is insufficiently massive to produce a black hole.
- 3. the intrinsic brightness of a celestial object (as distinct from its apparent brightness diminished by distance).
- 6. Population II stars are older, metal-poor, and found primarily in the halo of a galaxy.
- 7. a circle of white or colored light around the sun, moon, or other luminous body caused by refraction through ice crystals in the atmosphere.
- 8. A super massive black hole in the center of the Milky Way Galaxy
- 10. a star whose brightness changes, either irregularly or regularly.
- 11. a type of galaxy characterized by its smooth, ellipsoidal shape, ranging from nearly spherical to very elongated, with no spiral arms or prominent internal structure.
- 12. the rarefied gaseous envelope of the sun and other stars. The sun's corona is normally visible only during a total solar eclipse, when it is seen as an irregularly shaped pearly glow surrounding the darkened disk of the moon.
- 15. a massive and extremely remote celestial object, emitting exceptionally large amounts of energy, and typically having a starlike image in a telescope. It has been suggested that quasars contain massive black holes and may represent a stage in the evolution of some galaxies.
- 17. a galaxy emitting radiation in the radio-frequency range of the electromagnetic spectrum.
- 19. a unit of distance used in astronomy, equal to about 3.26 light years (3.086 × 1013 kilometers). One parsec corresponds to the distance at which the mean radius of the earth's orbit subtends an angle of one second of arc.
- 26. the magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs.