# Why is newton’s version of kepler’s third law so useful to astronomers?

## Why is Newton’s version of Kepler’s third law?

Because for every action there is an equal and opposite reaction, Newton realized that in the planet-Sun system the planet does not orbit around a stationary Sun.

## What is Newton’s version of Kepler’s third law?

Newton developed a more general form of what was called Kepler’s Third Law that could apply to any two objects orbiting a common center of mass. This is called Newton’s Version of Kepler’s Third Law: M1 + M2 = A3 / P2. Special units must be used to make this equation work.

## What is Kepler’s third law used for?

Kepler’s third law provides an accurate description of the period and distance for a planet’s orbits about the sun.

## How is Newton’s form of Kepler’s third law used to find masses of stars?

Newton’s form of Kepler’s third law gives the combined mass of the two stars: (mass 1 + mass 2) = (separation distance)3/(orbital period)2 if you use solar mass units, the A.U. … The lower-mass star moves faster and has a larger orbit.

## What is Kepler’s third law formula?

If the size of the orbit (a) is expressed in astronomical units (1 AU equals the average distance between the Earth and Sun) and the period (P) is measured in years, then Kepler’s Third Law says P2 = a3. where P is in Earth years, a is in AU and M is the mass of the central object in units of the mass of the Sun.

## What does P 2 a 3 mean?

There is a simplified version of this law: P2 = a3 where: The object must be orbiting the Sun. P = period of the orbit in years. a = average distance of the object from the Sun in AU.

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## What is Kepler’s constant?

Kepler’s Constant is only a constant if the object being orbited stays the same. So, anything orbiting the sun has the same Kepler’s Constant, just like anything orbiting the Earth has the same Kepler’s Constant. The Sun and Earth Kepler’s Constants will be different from each other.

## Where does Kepler’s third law come from?

The earth takes 365 days, while Saturn requires 10,759 days to do the same. Though Kepler hadn’t known about gravitation when he came up with his three laws, they were instrumental in Isaac Newton deriving his theory of universal gravitation, which explains the unknown force behind Kepler’s Third Law.

## What are Kepler’s 3 laws in simple terms?

There are actually three, Kepler’s laws that is, of planetary motion: 1) every planet’s orbit is an ellipse with the Sun at a focus; 2) a line joining the Sun and a planet sweeps out equal areas in equal times; and 3) the square of a planet’s orbital period is proportional to the cube of the semi-major axis of its …

## What determines the shape of an orbit?

Kepler’s First Law Describes the Shape of an Orbit

It is an ellipse—a “flattened” circle. … A focus is one of the two internal points that help determine the shape of an ellipse. The distance from one focus to any point on the ellipse and then back to the second focus is always the same.

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