Guidance of Orion watching
1. Background
Orion is a well known constellation because it consists of many bright stars and has a remarkablealignment of stars like 3 belt stars. At southern side of the 3 belt stars, you see another alignment of 3 stars
with smaller scale. If you use a telescope, you see a nebula around the middle star of the 3 stars. The nebula
is called Great Nebula of Orion. The nebula is one of the diﬀuse nebulae, which locates at the distance ofabout 1600 light-years away from the Earth. The nebula is a cloud that is mainly made with Hydrogen gas.
The gas cloud extends into 33 light-years across.
Galileo observed the Great Nebula of Orion. In his sketch of the Orion nebula, you see many stars.
However there is no gas cloud. Probably, he could not see the nebula gas clearly with his telescope.
In the Great Nebula of Orion, stars are forming. With telescope, you can see four stars in the brightest
area of the nebula, which is called the trapezium. The stars are newly born stars. The nebula is shining
because of starlight from the 4 stars.

2. Purpose
The aim of this activity is that children experience the feeling of wonder that Galileo had when heobserved celestial bodies for the ﬁrst time. When children observe the Great Nebula of Orion with the telescope which made by themselves, they will notice that there are many stars in the nebula. Teachers makechildren do sketch of the Orion nebula by themselves and lead them to ﬁnd many stars.

3. Observation Tips
It is not so diﬃcult to see the Great Nebula of Orion with low magniﬁcation telescope. As for theperson who use telescope for the ﬁrst time, it is advisable to have a practice session by using distant sceneryin daytime.

4. Steps(a) Observation and sketch of the whole of Orion constellation with the naked eyes
Use the ﬁrst worksheet. At ﬁrst, children observe the entire ﬁgure of the Orion with the naked eyes.
(b) Write any ﬁndings and/or questions
Write anything you found out and/or question from your observations in your sketch sheet under thesketch column.
The person with strong eyesight may be able to see a diﬀused image of the middle star of the small 3stars, which is the place of the Great Nebula of Orion.
(c) Observation and sketch with the telescope
Use the second sheet for observation and sketch with telescope. Children sketch both of the 3 belt
stars and the small 3 stars.
If the magniﬁcation of a telescope is too high to see the entire 3 stars image in the telescope's ﬁeld ofview, please put the middle star at the center of the telescope's ﬁeld of view.
Magniﬁcations of the telescopes are as follows:
For Hoshi-no-Techou Inc. telescope kit, the magniﬁcation is a 15 power(Focal length of the telescope is 273mm and focal length of the eye piece is 18.2mm).
For ORBYS Inc. telescopes kit, it is a 35 power(Focal length of the telescope is 420mm and focal length of the eye piece is 12mm).
(d) Write any ﬁndings and/or questions
Write anything you found out and/or question from your observations in your sketch sheet under thesketch column.

(e) Conﬁrm the existence of the Orion nebulaChildren compare their sketch with the photo or the Galileo's sketch of Orion nebula on the work
sheet of the post observation study. If they see the nebula by their observation, they did a better observation than Galileo did, because Galileo could not see the nebula itself.
Summarize your knowledge of the Great Nebula of Orion, which you learned from observations
with the telescope and through a textbook or the internet. Also, write down what you want to know more
and what you can do further.

5.NotesIn this activity, children watch the nebula in the Orion constellation. Teachers teach the nebula isthe place where stars are born in the Universe. Teachers also teach that nebulae are made by gas. In addition, it is better to explain the star formation mechanism and evolution, depends on children's levels ofunderstanding.
If it is possible, teachers observe the Orion nebula with a larger telescope beforehand. You can see
the nebula around the trapezium by a 10cm (or larger aperture) telescope with low magniﬁcation. If you
use the high magniﬁcation telescope, you can see 4 stars in the trapezium. With larger telescopes, you will
see the ﬁfth star in the trapezium.
Scientists know that there are many newborn stars in the trapezium region from their observation done bylarger than 1 meter in diameter telescopes.

Caution must be given to children that "Never watch the Sun through the telescope!”