Why do outer planets have shorter days

But nowhere in the literature can we find an accepted law of Planetary Rotation because everyone is convinced that there is nothing special about the rotation of the planets. We have a concept but not enough to express it in numbers. Log in to Reply. Constant Contact Use. Emails are serviced by Constant Contact.

Go on and get graphing! The Short Answer:. The longest day among those planets is 25 hours. That means our number line will go up to Along the bottom, write the names of the planets. Make a dot above the name of the planet next to the number of hours its day takes. Our graph is coming together! What do we do now? Color in the area below the dot to make a bar graph. More about the Earth!

Learn all about Earth! Learn about Earth's atmosphere! If you liked this, you may like: What Is a Meteor Shower? What Is a Barycenter? All About Mercury. More Less. The inner or inferior planets show the full range of phases, and they can never be very far from the sun in the sky. More on phases of Venus Mercury is similar. Inferior conjunction is earth-planet-sun. Superior conjunction is Earth-Sun-planet.

Maximum Eastern elogation is when the inner planet is visible in the western sky as an evening star its east of the Sun. Maximum Western elongation is when its visible in the eastern sky as a morning star. Here is a nice diagram.

For the outer or superior planets then conjunction is Earth-sun-planet planet furthest from Earth and opposition is Sun-Earth-planet planet closest to Earth see the previous diagram. They can also show phases but only from full to gibbous - they can never be new or crescent as they can never be between the Earth and the Sun. More on aspects and phases of the planets and planet rising and setting. The time between seeing a planet at a certain phase e.

This is different to the orbital period as the earth is not just sitting here while the planet rotates around - its also rotating anticlockwise around the sun. So the time taken for the planet to get back to where it started from with respect to the sun and Earth synodic period e. We can calculate this timescale - let the inner object have orbital period P1, and the outer one have orbital period P2.

The fast moving object gets back to where it started in time P1, but the slower object has moved on a bit.