I wanted to make these videos to help people with the Module Activities for Module 2.

Video to Help with Activity 1

In Activity 1, you'll ideally be using the sky-simulator windows (which I've put in Activity 1) to look at different directions in the sky. However, it might be helpful to specifically look at the four main points on the horizon, so as to see exactly how the stars appear to move, relative to the horizon, in each of those cases.

In this video, we'll look at all four of the main horizon points, S, E, N, and W, from both the Earth's northern hemisphere, and its southern hemisphere. At each of those four points, ask yourself "How do the stars seem to be moving, relative to the horizon?" Think about how you might use one or more of these words to describe the motion at each of the four main horizon points:

Leftward
Rightward
Upward
Downward
Arc
Circle
Clockwise
Counter-clockwise

You might want to write down your description for each of the eight horizon points (four in the northern hemisphere, four in the southern hemisphere), to prepare yourself for Activity 1.

Here's the supplemental video for Activity 1:

(I've submitted these videos for captioning, like the lecture videos, but that might take a few days.)

Video to Help with Activity 2

In Activity 2, you'll be comparing the 2 main ways that ancient and Renaissance-era astronomers thought about the solar system:

The Geocentric model, in which the Earth was thought to be the center of the universe
The Heliocentric model, in which the Sun was thought to be the center of the universe

Galileo and one of his former students realized that the phases of Venus could help decide between these two models. In a perfect world, you'd be able to run the UNL animations on the Activity 2 webpage. Those animations might or might not work for you, so I've made the following video to help in case they don't work. Some questions will pop up during the video, and you'll probably want to use the video's time slider to find the answers. Writing down these answers will probably help you when you go to Activity 2.

Here's the supplemental video for Activity 2: