Across
- 2. A ball of hot gas, primarily hydrogen and helium, that undergoes nuclear fusion.
- 4. A huge group of single stars, star systems, star clusters, dust, and gas bound together by gravity
- 5. how bright a star actually is
- 6. move or swing back and forth at a regular speed
- 9. the brightness of a star when viewed from Earth
- 10. Galaxy that contains our Solar System. The name derives from its appearance as a dim "milky" glowing band arching across the night sky, in which the naked eye cannot distinguish individual stars.
- 15. a graph in which the absolute magnitudes of stars are plotted against their spectral types. Stars are found to occupy only certain regions of such a diagram
- 16. 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
- 18. a natural object in space, such as the sun, moon, a planet, or a star.
- 19. huge galaxy that is round or oval in shape, only old stars
- 20. Space and all the matter and energy in it
Down
- 1. The theory that the universe originated in a huge explosion that released all matter and energy.
- 3. the distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission
- 7. A galaxy that has an undefined shape; irregular galaxies have large numbers of young stars and greats amounts of gas and dust are usually found near larger galaxies.
- 8. SI unit for temperature
- 11. A reaction that involves a change in the nucleus of an atom
- 12. a galaxy with a bulge in the middle and arms that spiral outward in a pinwheel pattern
- 13. An instrument that separates light into a spectrum
- 14. The actual brightness of a star
- 17. A measure of how hot or cold something is.