### Online College Courses for Credit

#### FREE EDUCATIONAL RESOURCES PROVIDED by SOPHIA

##### Are you a student?
Free Professional Development
+

# Planetary Systems

##### Rating:
(0)
Author: Lisa Ostrowski
##### Description:

At the end of the unit students will be able to describe how objects in the solar system are in regular and predictable motions.  Students will be able to explain that gravitational force is the dominant force determining motions.

By using this tutorial on Sophia.org and completing in class activities students will be able to describe that objects in the solar system are in predictable motions and that gravitational force determines these motions.

(more)

### Developing Effective Teams

*No strings attached. This college course is 100% free and is worth 1 semester credit.

29 Sophia partners guarantee credit transfer.

311 Institutions have accepted or given pre-approval for credit transfer.

* The American Council on Education's College Credit Recommendation Service (ACE Credit®) has evaluated and recommended college credit for 27 of Sophia’s online courses. Many different colleges and universities consider ACE CREDIT recommendations in determining the applicability to their course and degree programs.

Tutorial

## Bill Nye The Science Guy on Planets & Moons

You might feel like you're sitting still, but you're moving around a star. Our Earth is a planet, held in an orbit by the pull of a rope... no, wait. It's the pull of gravity. Take this one for a spin.

## Why Does The Moon Change

Describes why the moon changes shape

## Why Do Sattelites Saty in Orbit

Discovery Channel

They stay up there thanks to the magic of orbital mechanics. Not as complicated as they might seem, orbital mechanics are in play all around us. When you throw a ball, you are really putting it into orbit -- only a very shallow one doomed to end in a matter of a few yards. Now imagine shooting a cannon from the surface of the moon, at its highest point. Since the moon has no atmosphere, and no air resistance, if you launched the cannon ball at the appropriate speed it would orbit the entire moon without dropping to the ground -- fast enough to trace the curve of the moon and remain aloft. It's similar for a satellite, which needs to be about 200 miles (320 kilometers) above Earth's atmosphere to be free of it. Once there, satellite operators set the speed so that it essentially "falls" to Earth at the same speed that the curve of the Earth falls away from the satellite -- thus the satellite never comes down; it just keeps falling its way around Earth.

## Satellites in Orbit

You will be able to see the large amount of satellites in orbit

Source: gearthblog