Internet Version [Naruhodo no Mori] Vol. 15

by Yumiko Mori

---

Vol. 15     February 15th, 1996

Learning how big the space is (No.1)

Home science experiments for mothers of elementary school children

Materials required:

Nao's mom was so kind to Tae's mom, she had to listen to a story about the space.
Tae's mom started her story first about the distance between the earth and the moon.

If 10,000 km corresponds to 10 cm
Flight Height of the space shuttle Endeavor	500 km	5 mm
Diameter of the earth	13,000 km	13 cm
Distance to the satellite Himawari	36,000 km	36 cm
Diameter of the moon	3,000 km	3 cm
Distance to Moon	380,000 km	3.8 m
Diameter of the sun	1.4 million km	14 m
Distance to the sun	150 million km	1.5 km

Tae's Mom: "Let's assume this bigger ball is the earth.
Then the satellite Himawari (Japanese satellite for monitoring weather) is this far!"
She is pointing at 36 cm away from the ball.

Tae's Mom: "The moon is perhaps slightly smaller than this Ping-Pong ball in this magnification. Now, where do you think the moon should be in this model."
Nao's Mom: "The satellite Himawari is here, right? I think the moon should be further than that. How about here?"

She places the Ping-Pong ball 1 m away from the earth.
Tae's Mom: "Well, That distance seems quite reasonable, but the actual distance between the Earth and the Moon is much further."
Tae's Mom stands up and makes 4 large steps.
Tae's Mom: "This is where the Moon should be."
Nao's Mom: "Oh, my goodness! I can't believe that far."
Tae's Mom: "Yes, the moon is this far away from the Earth. Apollo11 came here all the way from the earth, the crew walked on the moon, and they came back to the earth."
Both Moms realized how great the Apollo achievement was by this model. Then they were totally impressed.
Tae's Mom: "Isn't it amazing? Now, we can extend our model to the Sun. The Sun would be a fire ball at 1.5 Km away and its diameter would be 14 meters."

Tae's Mom: "Next, how about the Space as a whole? Since the Space is much bigger scale than the Solar system, we have to change our scale to 1 mm as 10,000 million Km (or 10 billion Km)."
Her talk moves from the solar system to the galaxy, then to Magellan, Andromeda, and stars at 15,000 million light years away.

Nao's Mom: "I am totally overwhelmed. I am almost headachy."
Tae's Mom: "Are you OK? Tired?"
Nao's Mom: "I'm fine. Let me talk about our summer project. We made a history table in this summer. We learned the human history looks so tiny.
Tae's Mom: "That's right, when we compare with the space time, our history is very short indeed. "

Tae's Mom starts talking about the history of the Space.
Tae's Mom: "Shall we make a history table? We assume 1 year as 1 mm in length"
"The birth of the Space, so called 'Big Bang' , is 15, 000 million years ago. That corresponds to 15 thousands Km in length, which is close to a half way around the earth."

If 1 year is 1 mm long
Human life	80 years	8cm
First Homo Sapience	40,000 years ago	40 m
First Hominoid	2~4 million years ago	2~4 km
First Life	3500 million years ago	3500 km
The Earth was born	4600 million years ago	4600 km
The Sun was born	5000 million years ago	5000 km
Big Bang	15,000 million years ago	15,000 km

Tae's Mom continues her talk. She uses a globe for this talk.
Tae's Mom: "If we assume the present time is located at Tokyo station. Then Big Bang would be near St, Helena islands in south Atlantic Ocean."
"The sun would be born at Bangkok in Thailand. The earth would be born near Vietnam."
"At Mt. Fuji (100 Km from Tokyo), dinosaurs walking around."
"Homo Sapiens appeared 40,000 years ago. That is just 40 m. If the present time is very front of a train, the distance would be back of the 2nd car."
"All historical people are crowded at the front of the 1st car."
Nao's Mom: "Yes we found out the same thing,"

Tae's Mom: "If average life expectancy is 80 years, it would corresponds to 8 cm in length. Even Toshi or Tae are longer than 1 cm. 1 cm is very short, but you can see it. It's a little consolation, isn't it? "
"Human being is tiny in size compared with the space. But in terms of time. it is probably significant."

* Make sure to use tools such as balls and a globe. Children wouldn't understand without visual demonstration.

   Winter is a good season to observe stars at night. It'll be nice if you have an opportunity to share wonderful time with your children by looking at beautiful stars. Once we talked about the space with my children, they threw me a lot of questions which I did not know answers to. Learning about the space is very difficult. There are many unknown. I got so frustrated that on the next day I went to a library and read a book. When I finished reading, I got so impressed about the vastness of the space.

---