## HIUC General Education Course ピーター　ヴァンデェヴィアー
HIUC講師
カナダ出身

The college level astronomy course at HIUC Osaka sometimes has labs. A lab means that students do hands-on activities to better understand what they are studying. Here are a couple of the labs that they have done. Josh is the teacher of the class, not me, but I will try to give you some details about what the students are doing.

In one experiment, they wanted to demonstrate what happens to light as it travels through space. For example, when people look at stars they see light that has traveled from a far distance. As the light moves through space it hits dust and gas particles. This experiment shows what happens to light as it passes through space. The bowl with water in it represents outer space. Josh added some powdered milk to the bowl. The powdered milk represents the gas and dust particles that are in outer space. The flashlight is like a star, and it sends out light. What did we see in this demonstration? We could see how the light gets weaker (less bright) as it travels through space. Near the light source (the flashlight) we could see light that was a little blue and far from the light source we could see light that was a little red. Why did the light near the flashlight look blue? Why did the light far away from the flashlight look red?

You should take Josh’s class if you want to know. Or if you cannot wait that long for an answer, please read my next blog for the answer.

In another lab Josh’s class worked on calculating distance. You can find out how far away something is by using triangulation. I will try to give you a rough and simple idea of how this works. Think of a triangle - ▲. It has 3 sides and 3 points. Call one point A, another point B, and the final point C. Measure how long one side is – from point A to B. This is your baseline. You know how long this line is. Then you check what the angle is at point A and point B. Finally, you use these two angles, the distance from A to B, and a special mathematical equation to find out how far away point C is. Hikers and surveyors do this on earth all the time.

You can use the same basic idea to figure out the distance to nearby stars. It does not work for stars that are too far away. You look at the star from point A. You imagine a straight line from you to the star. The angle is 90 degrees. You walk to another place – point B. You know the distance from A to B. You use a protractor to find the angle at point B. You use this information and a special mathematical formula, and you can determine how far away the star is.

In class, the students did this using a protractor and a piece of paper with grids on it. They had to look at pictures of Totoro that Josh put around the room. Then, like real astronomers, they had to determine how far away the Totoros (the fake stars) were.

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