If a superior planet is observed from Earth to have a synodic period of 1.2 years, what is its sidereal period?

6.0 years.

Explanation:

When we are talking about the superior planets from the earth view, we are saying that the superior planets are those planets that are far from the sun as compared to that of the earth and they include planets such as the Mars, Jupiter, Saturn, Uranus, Neptune (and Pluto; since it is no longer considered as a planet, we can just exclude it).

To Calculate the sidereal period, we will have to make use of the formula below;

1/Sd = 1/EO - 1/Sy. Where Sd = sidereal period, EO = Earth's orbit = 1 and Sy = synodic period.

We are given the values of synodic period which is = 1.2 years.

So, 1/Sd = 1/1 - 1/1.2.

1/Sd = 1 - 0.833.

1/Sd = 0.17.

Sd = 5.88 years.

Approximately, sidereal period, Sd = 6.0 years.