1. Vocabulary Week 3-4
Sustaining Life

2. Asteroids
a small, rocky object that orbits the sun, usually in the belt between  Mars and Jupiter

3. Atmosphere
a layer of air, made up of many layers and gases that surround the Earth’s  surface keeping humans safe from the sun’s radiation

4. Galaxy
a large group of stars, dust, and gas.

5. Halley’s Comet
A comet seen about every 76 years.

6. Lightyear
unit of length equal to the distance that light travels in one(1)year

7. Nebula
large clouds of gas and dust

8. Satellite
a natural or man made object that orbits a planet

9. Solar system
The sun and all the planets , satellites , and comets that revolve around the sun.

10. Torino Scale
a system that rates the hazard level of an object moving towards Earth

11. Comets
a small body of ice, rock and cosmic dust that follows an elliptical orbit around the sun

12. Meteorite
a meteoroid becomes a meteorite when it strikes the surface of a body

13. meteoroids
Is in outer space. Once it enters a planet's atmosphere, it becomes a meteor.

14. Moons
Any planet's natural satellite.

15. Planets
Any of the celestial bodies (other than comets or satellites) that revolve around the sun in the solar system.  

16. Radiation
Thermal energy that travels in waves and can pass through empty space as well as some objects.

17. Space
The unlimited 3-dimensional expanse in which everything is located.

18. Sun
primary source of heat and energy for the entire Solar System

19. Meteors
A streak of light in the sky at night that results when a meteoroid hits the earth's atmosphere and air friction causes the meteoroid to melt or vaporize or explode.