Gui d ance of " Let's w atc h J upi ter! "1.

Background
One of the features of the Jupiter is having a lot of satellites and 63 satellites arefound now (July, 2008). It was Galileo Galilei that discovered the satellite around
Jupiter for the first time. He did the celestial observation that used the telescope for thefirst time ever in 1609, and in next year, he discovered four heavenly bodies around
Jupiter. This discovery is a counterpart of miniature version of solar system thought
about by the Copernican theory; another heavenly body turns round surroundings ofone heavenly body. At that time, it was not clarified that whether the Copernican theoryor the Ptolemaic theory was correct. However, Galileo's important discovery supported
the Copernican theory. These four satellites are being called now Galilean satellites.
The name such as Io, Europa, Ganymede, and Callisto is given to Galilean satellites inorder near Jupiter.
2.

Aim

The aim of this activity is that children also feel the surprise and impression similar toGalileo through his reliving. It is important to work and discovered satellites by thepower of children as much as possible. Therefore, the assistance of adult should be aminimum.
3.

Knack of observation

It might be difficult for the start to put the Jupiter in view, and to set the focus. I t i s
im por tan t to u se tri p od th at can be fir mly f ixe d. When the Jupiter enters vie w,
let's fix the telescope at once, and focus the telescope afterwards. Moreover, it is also
important to practice by using distant scenery in daytime.
4.

Flow of activityA) Observation and sketch
Let's do the observation and the sketch three times by using the work-sheet of the firstpage. First and second observation should be done on the same day and there should bethe interval of one hour or more between them. The change of the satellite’s position
could be noticed according to the position of satellite. However, some satellite’s
movement is small, and it will be difficult to notice the change of the position by thesame day’s observation. Then, let's do the third times on a different day. In the thirdobservation, it can be understood that there are 3 or four stars near Jupiter, and theposition has changed obviously compared with the sketch of the previous state.
If children have a motivation, you can increase the sketch column, and recommend tochildren to observe as a lot as possible though there are only three columns onwork-sheet.
B) Write what is noticed, and doubted
Let’s write what is noticed and doubted through the sketch under the sketch column.
C) Guess that they are moons of Jupiter by the sketch and the photographIn the second page of the work-sheet, there is a photograph of Jupiter and satellite thatwas taken at every alternate hour. From that photograph and the sketch, it can benoticed the heavenly body always exist around Jupiter, and they moves regularly.
D) Confirm how the Jupiter satellite looks from the earth
Through doing work, let's understand how to see moons of Jupiter from the earth byusing the third page of the work-sheet. Write the arrows like the example of Ganymede,and confirmed movement of satellite is the same as actual observation result.
E) Write what is understood today, and what you want to know moreAs a summary, let's write what is understood today like "There are three or moresatellites around Jupiter, and from the earth, they looks moving near Jupiter" etc. In
addition, let’s write what is wanted to know in the future as well. Those who support
children should encourage them by supplementing and supporting with these contents
and children can continue to act with the concern in the future.
5.

Notes

As written in "2. Aim", the objective of this activity is that children discovered Jupiter’ssatellite by themselves. Then, if children do not know the existence of moons of Jupiter,
it is better to turn down and execute the satellite of Jupiter.

6.MemoThere are two kinds of the combination of eyepiece and object lens fora refractor: theGalileo style and Kepler style.The Galileo style uses a convex lens for the object lensand a concavelens for the eyepiece. This combination makes an erect image. howeverthefield of view is very narrow. It has been used for opera glasseswith a low magnification
today.Meanwhile the Kepler style use the convex lenses for the object lensand theeyepiece. it was made by Johannes Kepler. With thiscombination, an inverted imageappears, but the field of view isrelatively wide. It has been used for observations ofcelestialobjects.Please try to guide the children's interest towards the history
oftelescope and its optical system through experience obtained withtelescopes of theKepler and Galileo styles.