Chapter 5 of "The journey of ideas" aims at showing that science is a global enterprise, based on international and intercultural collaborations. It illustrates the great contributions made by Arabic scientists to modern astronomy by presenting four of them.

Pupils will learn about the work of Al-Sufi in relating the Greek constellations to the Arabic ones through hand-on activities. They will be shown the importance of measuring the positions of stars accurately and of searching for patterns among groups of stars.

By comparison and by pattern recognition pupils learn to match groups of stars with their corresponding constellations. They also gain insight in the meaning of the Arabic names of the brightest stars as well as in their pronunciation.

Pupils learn that stars have different properties that can be measured directly (brightness, colours) or indirectly (temperature). They also learn by analogy to relate the colours of the stars with another important property: their temperature.

5.1.1. Set of cards “Arabic and Greek constellations” 5.1.2. Set of cards: “Arabic star names” 5.1.3. Set of images of this activity and constellation viewer (see chapter 3)

Help Al-Sufi match the Greek and Arabic constellations

Al-Sufi (image credits: Scorza)

The astronomer Al-Sufi lived and worked in the magnificent city of Isfahan in the late 9th Century. Try to find this city on the map of the “Journey of Ideas”! Al-Sufi drew maps of the night sky and improved on the charts drawn by the ancient Greeks. For several years he compared the constellations imagined by the Greeks with those of the Arabic tradition and tried to identify which stars were common to both. He ended up by choosing the Greek constellations for his “Book of the Constellations” but kept the Arabic names of the stars from his own culture. You can best understand what a great person he was to by joining him at work!

Discover Arabic star names and their meanings

Although other Arabic star names were introduced later, those selected by Al-Sufi in his “Book of the Constellations” comprise the largest list of Arabic star names that we use today. Many of these star names are linked to the original Arabic constellation of which they once formed part. For instance “Betelgeuse” is the brightest star of the Orion constellation. It means “the Hand of Al-Jawza”, the hunting goddess which a group of Arabs used to worship and saw at the sky on the place of Orion.

Discover the colors of the stars

When Al-Sufi started to observe the stars in Isfahan, he noticed the colours of some stars differed from others. This difference in colour had never been noted or recorded by Greek, Babylonian nor Egyptian astronomers! Al-Sufi thought that the colour is an important property of the stars and included it his catalogue together with their brightness’s and positions. Stars are hot due to nuclear fusion in their central regions: due to the high pressure, cores of atoms (like hydrogen) collide and fusion into heavier ones (Helium) and into Carbon, Oxygen, etc. giving rise to the elements that we know in chemistry.

Activity 5.1.1: Help Al-Sufi match the Greek and Arabic constellations / Ages: 7-14

Take the cards “Arabic and Greek constellations”. Note the Greek symbol of a vessel on the Greek constellation cards (right upper corner) and the piece of Arabic mosaic on the Arabic ones. Mix all the cards thoroughly. Now search for the pairs of Greek and Arabic cards containing the same group of stars. Look carefully at the patterns and distributions of stars. After you think that you have found the overlapping pairs, turn around the cards to check whether you are correct.

Card game Greek and Arabic constellations (image credits: Scorza)

Activity 5.1.2: Discover Arabic star names and their meanings / Ages: 7-14

ctivity Take the cards “Arabic star names” and mix on one side the largest cards (A) containing Greek constellations and the narrow ones (B) containing only the group of stars and the pronunciations of the names below. Look for the corresponding pairs by matching the constellations with the figures (see left Orion) on it with the group of stars (“Betelgeuse card”). Just as with the previous activity spot the patterns formed by the stars.

Card game the Arabic names of the stars (image credits: Scorza)

Activity 5.1.3 Discover the colors of the stars / Ages: 9-14

Activity 1: The colors of the stars

(a) Look carefully at the Orion constellation: Do you remember the name of the corresponding Arabic constellation? (See activity 5.1.1)

(b) Do you remember the name of the brightest star in the Orion constellation and what it means?

(c) Do you notice any difference between the colours of the stars in this constellation? What star colours do you see?

Orion constellation (credits: Hubble/ESA)

(d) Al-Sufi kept and used the Arabic names of stars in the Orion constellation in his “Book of the Constellations”. You can find the meaning in the table below:

Orion constellation (credits: Hubble/ESA)

Credit: Scorza

Cover the above picture of Orion with a piece of paper. Try to fill in the names of the four stars from the table in the picture bellow:

Orion constellation (credits: Hubble/ESA)

The colours and temperature of the stars

Have you ever seen an iron bar heated on the fire? In case not, just have a look at the picture bellow. When the iron bar is heated and become hotter and hotter, it turns red, then yellow, then white and finally (before it melts) blue!

Iron bar (credits: Blender3D)

(e) Look at the picture of stars taken with the NASA/ESA Hubble Space Telescope and try to answer the following questions:

Credit: HST image

Which are the hottest stars? Which are the coldest ones? Which stars have a medium temperature?
Does our Sun have a high, low or medium temperature?

We now know that stars have different colours because they are made up of hot glowing gas of different temperatures. Just as in the case of the iron bar, the star colours depend on how hot they are. The temperature of stars can sometimes reach 40 Million degrees in their inner cores! Al-Sufi didn´t know that the colours of stars are related to their temperatures, but he would certainly have loved to discover it!

(f) Take the constellation viewer and insert one after the other the cards with the following constellations:

• Orion
• Great Bear
• Lyon
• Lyra
• Taurus
• Scorpio

Credit: Scorza

For each constellation complete the table below: write the names of the brightest stars of these constellations, their colors as you see them in the viewer and with help of the table below, find out their temperatures:

Credit: Scorza

Credit: Scorza

Space Awareness curricula topics (EU and South Africa)

The journey of ideas, Constellations, stars