Outer Space

6. a pattern of climate and weather changes that occur during a year
7. the collection of planets and their moons in orbit around a sun, together with smaller bodies in the form of asteroids, meteoroids, and comets.
8. an imaginary line about which a body rotates.
12. one of the highly dense planets nearest to the sun that have a solid surface; Mercury, Venus, Mars, and Earth
16. Space and all the matter and energy in it
18. the movement of an object around another object
19. the spinning of a planet on its axis
21. large spiral galaxy that is home to Earth and the rest of our solar system, and about a trillion stars.
22. a thin disk of small ice and rock particles surrounding a planet.

1. the distance light travels in one year; about 6 trillion miles
2. an object that orbits a star, is large enough to have become rounded by its own gravity, and has cleared the area of its orbit.
3. planetary bodies made mainly of gases and no solid surface, including Jupiter, Saturn, Uranus, and Neptune
4. period of time when the sun shines at a maximum on one hemisphere and a minimum on the other
5. elongated circle, or oval shape; the shape of the planets orbit.
9. a round depression formed on the surface of a planet, moon, or other space object by the impact of a meteorite
10. path of one object around a more massive object due to gravity
11. a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
13. period of time when the sun shines equally on the northern and southern hemispheres
14. Spot dark area of gas on the sun's surface that is cooler than surrounding gases.
15. the outermost layer of the sun's atmosphere
17. the continuous flow of charged particles from the sun that permeates the solar system.
20. rise and fall of the Earth's water due to the pull of the moon's gravity