# Astronomy and Kepler's Laws

1. Apr 13, 2005

### flipper2388

In class, we've been assigned a project over astronomy. We have graphed an equation for 6 of Jupiter's moons and the planets (separately), and the equation was a power equation T=ar^b. T is the orbital period of the moon or planet, r is the distance from the planet (or sun), and a and b are constants that we've determined. We also have to include a discussion on the three main laws that describe the motion of heavenly bodies, who they are named for, why s/he is the one that gets this honor, and which of the laws pertains to the calculations done here.

The part I need help with pertains to the laws. I believe they are Kepler's laws, but I don't know why Kepler got the honor or which law pertains to the calculations (or equation). Any help?

2. Apr 13, 2005

### tony873004

There's also Newton.

Check your forumla. The constant should not be the exponent. Look up Kepler's 3rd law.

3. Apr 13, 2005

### flipper2388

The formula is the one she gave us, so I can't change it or anything. It's the one that the whole project is based on and she gave it to us exactly like that. That's the reason I got confused is because the formulas for Kepler's laws aren't anything like this one, but yet it has to relate to one of three main planetary laws.

Or what laws of Newton relate to this? (There has to be three laws of his that relate to planetary motion, though, if I were to use him)

Last edited: Apr 13, 2005
4. Apr 13, 2005

### SpaceTiger

Staff Emeritus
You're right that the laws she's referring to are Kepler's laws. The answer to the questions she's asking are mostly historical in nature, so you could easily find it in a google search of kepler's laws. For reference, here's the law for the solar system:

$$T^2=\frac{4\pi^2r^3}{GM_{sun}}$$