Across
- 5. a unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 1012 km
- 7. a celestial object of very small radius (typically 18 miles/30 km) and very high density, composed predominantly of closely packed neutrons.
- 10. the magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs.
- 11. he range of wavelengths or frequencies over which electromagnetic radiation extends.
Down
- 1. the magnitude of a celestial object as it is actually measured from the earth.
- 2. 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.
- 3. Hertzsprung–Russell diagram, abbreviated H–R diagram or HRD, is a scatter graph of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their spectral classifications or effective temperatures.
- 4. a star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.
- 6. the intrinsic brightness of a celestial object
- 8. a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
- 9. a small very dense star that is typically the size of a planet. A white dwarf is formed when a low-mass star has exhausted all its central nuclear fuel and lost its outer layers as a planetary nebula.