As the semimajor axis of a planet increase, the orbital period will decrease and the speed of the planet will decrease.
<h3>What is Kepler's second law?</h3>Kepler's second law of planetary motion describes the speed of a planet traveling in an elliptical orbit around the Sun.
This law exaplains the speed of planets around the sun, the speed of the planet increases as it nears the sun and decreases as it recedes from the sun.
From the findings, the astronomical unit of the Mercury is 0.387 and the orbital period is 0.24 year.
From the equation above, as the semimajor axis of a planet increase, the orbital period will decrease and the speed of the planet will decrease.
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