1. Does Zero Gravity Exist? If so, what is it?

2. Gravity holds many objects together in orbits. Moons…

3. …more moons… …satellites…

4. …comets… Comet Neat

5. …more comets… Comet Maccholz

6. …and astronauts and their space shuttles. But wait…

7. Why do astronauts in orbit seem to float? Have they escaped Earth's gravity?

8. G= 6.67300 × 10 -11 N m 2 /Kg 2 M Earth = 5.98*10 24 Kg R Earth = 6.378 x 10 6 m Calculate the force of gravity on a person on Earth. You can use your own mass. Then calculate the force of gravity if you were an astronaut in orbit. Shuttles orbit the Earth at around 200 miles (about 322 km) above the ground. F grav =G*M 1 M 2 /r 2

9. According to your results, does all the floating make sense? Is the force of gravity on Earth that much different than the one astronauts feel? What is happening here?

10. The astronauts and their craft are falling. They, AND their ships are in constant free-fall.

11. Look at F grav =G*M 1 M 2 /r 2 Gravity is always attractive solar system galaxies EVERYWHERE!

12. Clusters of galaxies and gravitational lensing

13. That's it!

14. http://www.nasa.gov/returntoflight/multimedia/RTF_videos_search_agent_arch ive_1.html