Internet version [Naruhodo no Mori] Vol.23

by Yumiko Mori

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Vol. 23     November, 15th, 1996

Watching How Stars Move

Home science experiments for mothers of elementary school children

Mom cannot give up yet.  She is still looking at the night sky.
Mom: "Tae!  Come here!  I can see stars now!"
Tae: "All right!  I'm coming as soon as I put my jacket on."
Mom and Tae grab a glass lid and a flashlight, and go outside of the house.

Tae: "Mom, can we avoid anywhere too dark?  It's scary. We can see enough stars here."
Mom: "Can you see a house over there? It has a rooftop. That would be the best place to see stars. I wish we had a rooftop like that on our house."
Tae: "The north is this way."
Mom: "We have to remember where we stand. How about this manhole? You position the North Star at the center of the lid."
Tae: "Put small stickers for visible stars. Can I put a sticker on that reddish flickering star?"
Mom: "That is really beautiful one."

10 o'clock at night.
Tae and Mom go out with the lid, on which they marked positions at 8 o'clock.
Tae: "Oh! Stars are now at completely different positions."
Mom: "How about this one?"
While stars in the eastern sky moved quite far, the Cassiopeia constellation moved only slightly to the left.

Tae: "Mom, doesn't that star move?"
Mom: "North Star?  Actually it is moving on a very small circle. No, actually the star is not moving but our earth is rotating instead."
Tae: "You mean some stars move by longer distances, but the other stars move only short distances. That's interesting!"
Mom: "Yes, but it is again because the earth is rotating. Well...I am getting confused completely."

Materials

How to watch star movement

1. During daytime, find a place where you can have good view of the northern sky.
   Preferably a darker place without bright street lights.

2. Around at 8 PM, go out with a glass lid, a plastic board, seals, a flashlight, and a magnetic compass.

3. Look for the North Star in the northern sky.
   Look the Cassiopeia for Between November and January. Look for the Big Dipper after February (Refer the figure).

4. Hold up a glass lid over your head. Aim toward the North Star and adjust the position of the lid, so that the center of the lid overlaps the North Star.
   (If you use a plastic board, place a sticker on the North Star position.)

5. Look for bright stars. Put stickers with various colors on those positions.
   You can also investigate stars on the southern, western and eastern sky using separate plastic boards.

6. At 10 PM, you stand at the same position. Hold the glass lid and look up stars.

• It may be very difficult if you can see too many stars, because you can not identify stars among many stars.
  It's best when you can count bright stars easily.

• If you are interested in stars other than northern sky, you can mark on something stationary such as tall buildings or power lines.

• Concentrate on the star movements rather than constellations. Check your book when you encounter difficulty.
  When you check a star map, make sure you set correct date and hour.

• We tried a clear plastic umbrella and a glass bowl as well. But these tuned out to be no good, because we could not see stars well through these objects.

   There is a science museum near my parents' house. When we visited there, I saw a model in which the positions of the Big Dipper stars are presented in 3D map (a view of the Big Dipper from very far away from the Earth). I learned that the 7 stars that form the Big Dipper are not lined up at the same distance from the earth. Some of the stars are closer, while the others are far from the earth. I realized constellations are meaningless for aliens on other planets. Ancient people had to depend on stars for their calendar. They must have stared nightly sky for many times as we look at our wall calendars, Today it is difficult to see stars in cities because of city lights. Ironically we have lost necessity for looking up stars every night.

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