Across
- 4. a fixed luminous point in the night sky which is a large, remote incandescent body like the sun.
- 7. a body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing.
- 9. an apparatus for producing and recording spectra for examination.
- 10. very long-period waves that move through the ocean in response to the forces exerted by the moon and sun.
- 12. the curved path of a celestial object or spacecraft around a star, planet, or moon, especially a periodic elliptical revolution.
- 14. a system of millions or billions of stars, together with gas and dust
- 16. A celestial object that orbits around a planet
- 17. a rotating circumstellar disk of dense gas surrounding a young newly formed star
- 20. 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.
- 21. a star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.
- 22. an unmanned exploratory spacecraft designed to transmit information about its environment.
- 23. an optical instrument designed to make distant objects appear nearer, containing an arrangement of lenses, or of curved mirrors and lenses, by which rays of light are collected and focused and the resulting image magnified.
- 24. an artificial body placed in orbit around the earth or moon or another planet in order to collect information or for communication.
- 25. a coherent, typically large body of matter with no definite shape
Down
- 1. a small very dense star that is typically the size of a planet.
- 2. a two-dimensional graph, devised independently by Ejnar Hertzsprung (1873–1967) and Henry Norris Russell (1877–1957), in which the absolute magnitudes of stars are plotted against their spectral types.
- 3. a tide just after the first or third quarters of the moon when there is least difference between high and low water.
- 5. a tide just after a new or full moon, when there is the greatest difference between high and low water.
- 6. how astronomers explain the way the universe began
- 8. a region of space having a gravitational field so intense that no matter or radiation can escape.
- 11. a unit of astronomical distance equivalent to the distance that light travels in one year
- 13. a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.
- 15. a spectrum of the electromagnetic radiation emitted by a source.
- 18. a change in frequency due to the Doppler effect.
- 19. All existing matter and space considered as a whole.