Across
- 1. the tide with the least difference between consecutive low and high tides
- 3. a galaxy in which the stars and gas clouds are concentrated mainly in one or more spiral arms.
- 6. a star and all the other objects that revolve around it
- 11. the standard unit that astronomers use to measure the size of stars
- 12. describes phases following a new moon, as more of the Moon's lighted side becomes visible
- 19. Solar system model based on the belief that the sun is the center of the universe
- 20. the time required for Earth to rotate once on its axis
- 21. the spinning motion of a object on its axis
- 24. the tide with the greatest difference between consecutive low and high tides
- 25. phase when the moon is located directly between the earth and sun
- 26. A sudden eruption of intense high-energy radiation from the sun's surface
- 27. line above which polar day (24 hours of daylight) and polar night (24 hours of darkness) are possible
- 29. the distance light travels in one year
- 30. an object that revolves around another object in space
- 31. the blocking of sunlight to Earth that occurs when the moon is directly between the sun and Earth.
- 32. A region of the solar system that is just beyond the orbit of Neptune and that contains small rocky bodies and dwarf planets
- 33. describes phases following the full moon during which the visible surface of the moon decreases
Down
- 2. regions close to the equator which receive direct sunlight nearly all year
- 4. areas of gas on the sun's surface that are cooler than the gases around them
- 5. A galaxy shaped like a round or flattened ball, generally containing only old stars
- 7. The average distance between Earth and the sun, used to measure distances in the solar system
- 8. A force of attraction between objects that is due to their masses.
- 9. the difference in levels of ocean water at high tide and low tide
- 10. An oval shape as opposed to a circular shape
- 13. A model of the universe in which Earth is at the center of the revolving planets and stars.
- 14. phase when the entire side facing Earth is illuminated
- 15. the time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of equal length (about September 22 and March 20).
- 16. A galaxy that has an undefined shape, large numbers of young stars, and greats amounts of gas and dust
- 17. the blocking of sunlight to the moon that occurs when Earth is directly between the sun and the moon
- 18. An object that orbits the sun and is spherical, but has not cleared the area of its orbit.
- 22. A loop of gas that protrudes from the sun's surface, linking parts of sunspot regions
- 23. either of the two times of the year when the sun is at its greatest distance from the celestial equator
- 28. the movement of an object around another object