Animating the Solar System

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Building the Solar System
Mapping the Solar System
Animating the Solar System
Visualizing the Solar System
Visualizing the Days and Seasons
Visualizing the Motion of the Sun

In this lesson, you animate the rotation of the Earth over the course of a year by making the Earth spin on its axis 365 times. Then you animate the Moon going around the Earth and the Earth going around the Sun.

By using the default playback speed of 30 frames per second, and setting the number of frames to 1825, the animation will last just over 60 seconds (1825 f ÷ 30 fps = 60.83 s).

Why use 1825 instead of 1800? Because it causes the Earth to rotate exactly 5 frames per day (365 x 5 = 1825). This regular division of 5 frames per day will later help you visualize the sun's apparent movement in the sky from a location on the Earth.

Open Seasons02.max.

Click Time Configuration.
In the Time Configuration dialog box, set the animation Length to 1825 and press Enter. Then click Close.

Turn on the Animate button.
Drag the time slider all the way to the right.
In the Top viewport, rotate the Earth slightly in Z:

In the track bar, select the key all the way to the left at frame 0.
Right-click on the key and choose Earth:Rotation:

The Earth:Rotation dialog box appears for key 1. Click the right arrow to advance to key 2. Set the Angle to 131,400:

Close the dialog box and play back the animation.
From frame 0 to 1825, the Earth rotates on its axis 365 times. (131,400° = 360° x 365 days)
Stop the animation and drag the time slider back to frame 0.

Select the Earth and open the Motion panel.
Click the Parameters tab.
Open the Assign Controller rollout and click Position:

Click the Assign Controller button. Choose Path and click OK:

In the Path Parameters rollout, click Pick Path. Then click the Earth's orbit.
The Earth moves to the beginning of the path:

Drag the time slider from 0 to 1825. The Earth orbits the Sun one time.

Select the Moon's Orbit.
Assign the Moon's Orbit a Path controller. Pick the Earth's Orbit for the path:

Select the Moon.
Assign the Moon a Path controller. Pick the Moon's Orbit for the path:

Play the animation.
The Moon goes around the Earth while the Earth goes around the Sun.

With the Moon still selected, turn on the Animate button and drag the time slider to frame 1825.
In the Motion panel, change the Percent value to 1239. The Moon moves to a new position along its orbit.
Play the animation. The Moon orbits the Earth every 29.45 days, which equals 12.39 times per year.

Select the Moon's Orbit and activate the Front View.
Click Zoom Extents Selected.
In the Front view, rotate the Moon's Orbit 5°.
Select the Earth. Rotate the Earth 23.5°. The Equator and Pole rotate with it:

Play the animation. As the Earth and Moon orbit the Sun, they remain tilted in the same direction:

Save your work as Seasons03.max.

Next: Visualizing the Days and the Seasons