Across
- 2. The force that attracts a body towards the centre of the earth, or towards any other physical body having mass.
- 3. A medicine (such as penicillin or its derivatives) that inhibits the growth of or destroys microorganisms.
- 7. The emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles which cause ionisation.
- 10. The process in which green plants convert sunlight into nutrients.
- 11. A celestial body moving in an elliptical orbit round a star.
- 12. A region of space having a gravitational field so intense that no matter or radiation can escape.
- 15. Seventh planet from the sun, ironically, due to its name, this planet is a gas giant.
- 17. All existing matter and space contained into one place.
Down
- 1. The rate per second of a vibration constituting a wave, either in a material (as in sound waves), or in an electromagnetic field (as in radio waves and light).
- 4. The process in which hot substances rise and cooler substances sink
- 5. The smallest particle of a chemical element that can exist.
- 6. Often described as the red planet, it is the fourth planet in the solar system.
- 7. Emitting or relating to the emission of ionizing radiation or particles.
- 8. A small rocky body orbiting the sun.
- 9. Sound or other vibrations having an ultrasonic frequency, particularly as used in medical imaging.
- 13. A pure substance that can't be broken down.
- 14. A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
- 16. The regularly repeated elliptical course of a celestial object or spacecraft about a star or planet.