Across
- 4. A push or a pull that can change an object’s motion.
- 7. A force that acts without objects touching, such as gravity.
- 8. The force of gravity acting on an object.
- 11. The force that attracts objects with mass toward each other.
- 12. The unit used to measure force.
- 15. An icy object that orbits the Sun and forms a glowing tail when near the Sun.
- 18. A large body formed from planetesimals that may eventually become a planet.
- 20. A small rocky object that orbits the Sun.
- 23. The Sun and all the objects that orbit around it, including planets, moons, asteroids, and comets.
- 25. Motion of an object when gravity is the only force acting on it.
- 27. process where particles of dust and rock stick together to form larger bodies.
- 28. A force that slows objects moving through air.
- 30. The planet we live on. It orbits the Sun and has gravity that pulls objects toward its surface.
Down
- 1. A shape or path that forms a circle. Many objects in space move in nearly circular orbits around larger objects.
- 2. The strength of gravity at a certain place. On Earth it is about 9.8 N/kg.
- 3. Forces that cancel each other out so an object does not change motion.
- 5. A force that acts when objects touch each other (for example when a table holds up a book).
- 6. A young star forming from collapsing gas and dust.
- 9. The area around a massive object where another object feels the force of gravity.
- 10. Forces that cause an object to start moving, stop moving, or change direction.
- 13. A huge cloud of gas and dust in space where stars and planetary systems can form.
- 14. A streak of light produced when a small space rock burns up in Earth’s atmosphere.
- 16. A piece of rock from space that survives the atmosphere and reaches the ground.
- 17. Small early objects that formed from dust and rock and later combined to make planets.
- 19. collapse The process where gravity pulls gas and dust together to start forming stars and planets.
- 21. A perfectly round three-dimensional shape, like a ball. Planets and stars are approximately spherical because gravity pulls matter equally toward the center.
- 22. The path an object follows around another object in space.
- 24. The star at the center of our solar system. Its gravity keeps the planets, asteroids, and comets in orbit around it.
- 26. A natural satellite that orbits a planet. Earth’s Moon orbits Earth because of gravity.
- 29. The amount of matter in an object. Mass is measured in kilograms (kg).