Across
- 5. An astronomical event where one celestial body moves into the shadow of another, or passes directly between a larger body and the observer, temporarily blocking the light.
- 10. An imaginary, giant rotating sphere of infinite radius centered on Earth, onto which all celestial objects can be projected for mapping purposes.
- 12. The twice-yearly event when the Sun reaches its highest or lowest point relative to the celestial equator, resulting in the longest and shortest days of the year.
- 13. The apparent yearly movement of the Sun against the background stars, caused by Earth's actual orbit around the Sun.
- 15. The apparent backward or westward motion of a planet across the sky against the background stars, which occurs as Earth passes that planet in orbit.
- 17. The apparent path that the Sun traces across the celestial sphere over the course of a year, which also represents the plane of Earth's orbit around the Sun.
- 19. A division of the year marked by changes in weather, ecology, and the amount of daylight, caused by the tilt of Earth's axis as it orbits the Sun.
- 20. The twice-yearly event when the Sun crosses the celestial equator, resulting in roughly equal lengths of day and night across the globe.
Down
- 1. A small geometric circle used in the geocentric model along which a planet moves, the center of which itself moves around a larger circle.
- 2. A band of the sky extending about 8 degrees on either side of the ecliptic, divided into 12 traditional signs through which the Sun, Moon, and planets appear to move.
- 3. The apparent daily rotation of the entire sky from east to west, caused by Earth's actual rotation on its axis from west to east.
- 4. In ancient and medieval science, the fifth element (quintessence) believed to fill the universe beyond the terrestrial sphere and compose all celestial bodies.
- 6. Relating to the sky, outer space, or the astronomical objects observed in the heavens.
- 7. An ancient astronomical model that places a stationary Earth at the center of the universe, with all planets, the Moon, and the Sun orbiting it.
- 8. Relating to the Earth, its land, or planets that share Earth-like characteristics (such as being rocky and solid).
- 9. The astronomical model that places the Sun at the center of the solar system, with Earth and other planets revolving around it.
- 11. One of the 88 officially recognized regions of the celestial sphere used to map the sky, often named after traditional star patterns.
- 14. The large circular path centered on (or near) Earth along which the center of a planet's epicycle travels in the geocentric model.
- 16. A prominent, recognizable pattern or group of stars that is not an official constellation, such as the Big Dipper or Orion's Belt.
- 18. The figure-eight curve that represents the changing position of the Sun in the sky at the exact same time of day throughout a calendar year.