If the average distance between Earth and the Sun were doubled, what changes would occur in the sun's gravitational pull on Earth and Earth's period of revolution?

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Answer 1 · 2017-01-04T13:31:34

Doubling the distance from the sun reduces gravitational pull and increases the orbital period.

Using Newton's model of gravity the force or pull #F# is given by:

#F=(GMm)/r^2#

Where G is the gravitational constant, M is the mass of the Sun, m is the mass of the Earth and r is the distance between Sun and Earth.

So, doubling the distance reduces the force by a factor of 4.

Kepler's third law relates the semi-major axis distance #a# in AU(Astronomical Units) to the orbital period #P# in years.

#P^2=a^3#

In the case of Earth in its current position #P=1# and #a=1#. If the distance was doubled then #a=2# and:

#P^2=2^3=8#

This would make the orbital period #P=2.828# years.