Alejandro P1

3. space rock falling into the atmosphere
4. a region of the solar system beyond the orbit of neptune
7. A common tectonic feature found on Mercury
10. orbital or rotational motion of an object in the direction opposite the rotation of its primary
13. a fundamental system in condensed matter sciences and the main constituent of gas giant planets
14. a planet smaller than normal
16. a region of space between the orbits of Mars and Jupiter where most of the asteroids in our Solar System are found orbiting the Sun
17. large objects made of dust and ice that orbit the Sun
18. a unit of length, roughly the distance from Earth to the Sun and approximately equal to 150 million kilometers

1. a planet that is composed primarily of silicate rocks or metals
2. bits of comet debris, most no larger than a grain of sand, create streaks of light in the night sky as they burn up in Earth's atmosphere.
5. a measure of how non-circular the orbit of a body is
6. a large planet mostly composed of helium and/or hydrogen
8. a circle which has been squashed or flattened a bit.
9. small piece of debris from a comet
11. the building blocks of planets
12. the region around a star where an orbiting planet could host liquid water and, therefore, possibly support life
15. lumps of iron that orbit the sun