What should I pay attention to when observing constellations?

The first part explains the meaning of constellations: in order to understand and study the stars, people divide the starry sky into many regions, which are called constellations.

The second part guides students to know the spring constellation. In spring, students are only required to know the Big Dipper in Ursa Major and the North Star in Ursa Minor. This part is divided into two layers:

1. Tell the students: In the northern sky in the spring night, you can see the famous Big Dipper, which belongs to the constellation Ursa Major and is an obvious sign of finding Ursa Major. The illustrations in the text draw the images of the Big Dipper and the constellation Ursa major, so that students can identify them with the pictures.

2. Teach students how to use the Big Dipper to find the North Star, and how to use the North Star to tell the direction at night. This is of great practical value.

The third part guides students to observe constellations and their movements. These include two projects:

1. At night, look for the Big Dipper and Polaris in the northern sky. To know the constellation, you must actually observe and identify it at night; You can't recognize the stars just by looking at the star map, nor can you master the ability to recognize the stars.

2. Observe the position change of the Big Dipper in the sky. At different times of the day, the position of the Big Dipper in the sky changes counterclockwise, but the arrangement of the seven stars does not change. Through this activity, students can lay a foundation for learning about the rotation of stars and the earth in the future; You can also consolidate the methods you have learned to observe the motion state of objects with reference objects.

The fourth part guides students to know summer constellations. This part is divided into three layers:

1. Explain the characteristics of the Milky Way.

2. Explain the characteristics of prominent constellations in summer-Aquila (focusing on Altair) and Lyra (focusing on Vega).

3. Arrange students to look for the Milky Way, Altair and Vega when summer comes. In summer, teachers should remind students to observe.

Second, the purpose requirements

1. Through the teaching of this course, students are required to know what constellations are and how to identify the Big Dipper, Polaris, Altair, Vega and the Milky Way.

2. Cultivate students' observation ability (look for obvious constellations or bright stars in spring and summer according to the requirements of the text, and observe the movement of constellations) and induction and generalization ability (summarize the law of constellation orientation changes in the sky in one day).

3. By observing the movement of constellations, students can realize that the movement of celestial bodies is regular.

Third, preparation before class

Teachers prepare: flip charts or slides-the Big Dipper and Polaris, Ursa major, Lyra and the Milky Way, and observe the movement of constellations with reference objects.

Fourth, the teaching process

Introduce a new course

1. Narrator: Last class, we learned how to measure the height of the sun. After class, we measured the changes of the sun's height and temperature during the day.

Ask questions:

(1) How does the height of the sun change in a day? Name the time of observation and the height of the sun. What are the rules? (From morning to noon, and then to night, the height of the sun is from small to large, and then to small, and the height of the sun is the highest at noon. This happens every day. )

(2) What is the law of temperature change in a day? (From morning to noon, at night, the temperature goes from low to high and then to low, with the highest temperature at 2 ~ 3 pm. It's always like this on sunny days. )

3. Discussion: According to the above observation, do you think the change of sun height is related to the change of temperature in a day? What does it matter? what do you think?

4. Description: We already know that the heat on the earth mainly comes from the radiant heat of the sun, and the amount of radiant heat absorbed by an object is related to the angle of sunlight irradiation (we did this experiment in the lesson "The Sun" in Volume 6). Now we know that the rising and falling law of the sun's height is basically the same as that of the temperature in a day. It can be inferred that the change of solar height is related to the change of temperature in a day, and the change of solar height is an important factor affecting the change of temperature, and the change of temperature changes with the change of solar height.

5. Dialogue: In the past science class, we studied the sun and the moon. Besides the sun and the moon, what else is in the sky? (star)

6. Narrator: In this lesson, we learn how to observe and identify stars.

Learn new lessons

1. Guide students to establish the concept of constellation.

(1) explanation: Many students are very interested in the stars, and they like to observe the stars in the sky from an early age. There are many stars in the sky. If you look closely, you will find that there are many stars whose mutual positions are constant, and the connecting lines between them can form a certain shape-triangle, quadrangle, spoon, human figure, animal shape ... (At this time, it is best to explain intuitively with a big star map, or you can explain it with a board painting. In order to understand and study the stars, people divide the starry sky into many regions, which are called constellations. Each constellation has many stars. People imagine various figures according to the shapes of some bright stars in the constellation, and give various names to the constellation, such as Ursa Major, Ursa Minor, Orion, Pegasus and Leo.

(2) Question: What is a constellation? Is the constellation a star? (Again, the constellation is an area of the starry sky, including many stars. )

2. Guide students to know the constellations in the northern sky in spring.

(1) Explanation:

In different seasons, the observed constellations are different. It's spring now. Let's meet some spring constellations first. The starry sky above us is like a cauldron on the earth, which can be divided into two parts: the northern sky and the southern sky. There are many constellations in the north sky and many constellations in the south sky. In this lesson, first get to know the constellations in the northern sky in spring.

(Show the Big Dipper. )

(2) Talk: On a spring night, you can see seven bright stars in the northern sky forming a spoon. Do you know what they are called?

(3) Description: These seven stars are the famous Big Dipper. These seven stars have different brightness, five are brighter and two are not. The brightness of a star is expressed by magnitude, and the smaller the magnitude, the brighter it is. Among the Big Dipper, five brighter stars are second-class stars, and the other two are third-class. In the star map, stars with different magnitudes are represented by different symbols, for example, some are represented by points with different sizes. The bigger the point, the brighter the star.

(Show the map of Ursa Major.

(4) Description: The Big Dipper belongs to the constellation Ursa major, located at the bottom and tail of Ursa major, and is a remarkable sign for finding Ursa major.

Show me the map of the Big Dipper and the North Star. )

(5) Description: As shown in the figure, the connection between the two stars on the Big Dipper spoon is extended, and there is a brighter star about 5 times the distance between the two stars, which is the famous Polaris.

Dialogue 6: Do you know what Polaris has to do with us?

(7) Description: Polaris is always in the true north direction. At night, when there is no compass or other signs to tell the direction, Polaris can be used to tell the direction, which is very useful in navigation, war, field trip and travel. Therefore, we must learn to recognize Polaris; To recognize Polaris, we must first learn to recognize the Big Dipper.

3. Guide students to observe the movement of constellations

(1) Talk about: According to your experience, will the spoon shape of the Big Dipper change at different times of the day? Will the position of this spoon change in the sky?

(2) Narration: To understand this problem, we can observe it at different times of the day. (Show the use of reference objects to observe the constellation diagram. ) When observing, just like observing the movement of the moon, choose an obviously fixed object as a sign to see if the positional relationship between the Big Dipper and this object has changed; Stand in the same position every time you observe.

4. Guide students to know summer constellations and the Milky Way.

Show me the summer constellation. )

(1) Explanation:

In summer, you will see a bright white band in the sky. This band of light is called the Milky Way, commonly known as Tianhe. The Milky Way is made up of many stars far away from us. Because these stars are too far away, our eyes can't distinguish the stars one by one. They look white.

On the east bank of the Milky Way, there is a bright star. On both sides of this bright star, there are two darker stars, and the three stars form a polar shape. This bright star is called Altair.

On the west bank of the Milky Way, across the river from the Altair, there is a particularly conspicuous bright star that emits white light, and there are four relatively dark stars near this bright star, forming a shuttle shape. This bright star is called Vega.

Altair belongs to the eagle and Vega belongs to Lyra. The well-known story of Cowherd and Weaver Girl in China is based on these two stars.

(2) Talk: Who knows the story of the Cowherd and the Weaver Girl? Tell me about it.

(3) Narration: The story of the Cowherd and the Weaver Girl is just a myth. In fact, Altair is far away from Vega. If you take a photon rocket flying 300,000 kilometers per second, it will take 16 years from Altair to Vega. So why are the constellations of these two bright stars called Aquila and Lyra? This is named after foreign fairy tales.

Integrate applications

1. Narrator: In this lesson, we learned some constellations in spring and summer.

Ask questions:

(1) Where is the Big Dipper in the sky? What are the characteristics of its appearance? Which constellation do you belong to?

(2) How to find Polaris?

(3) How to distinguish Altair from Vega?

arrange work

1. At night, distinguish the Big Dipper from the North Star.

2. When summer comes, look for Altair and Vega.

3. Observe the position of the Big Dipper in the sky at different times of the day (such as 7: 00 pm, 8: 00 pm and 9: 00 pm). Has the arrangement of the seven stars changed?

Verb (abbreviation of verb) reference materials

1. constellation

In order to understand the starry sky, the Babylonians divided the celestial sphere into many regions, called "constellations". Many names of constellations are animal names or characters in Greek mythology. At present, there are 88 constellations in the world, all developed from ancient Greek constellations. Each constellation can be identified by the special distribution of bright stars in it.

Step 2 be important

The brightness of celestial bodies is divided and described by magnitude. People divide the stars visible to the naked eye into several grades. The brighter the star, the smaller the magnitude. Stars barely visible to the naked eye are class 6. The magnitude of Sirius is-1.4, the moon is-12.7, and the sun is -26.7. To see stars darker than level 6, you need to use a telescope. The larger the aperture of the telescope, the more dark stars you can see.

3. Ursa Major and Ursa Minor

These two constellations are the brightest and most recognizable constellations near the north celestial pole, which have been known to people since ancient times.

There are more than 100 visible stars in Ursa major, including five secondary stars and many tertiary and quaternary stars, so it is remarkable. The Big Dipper in Ursa Major is the most eye-catching. These seven bright stars form a big spoon in the northern sky. Extend the connecting line of the two stars at the end of the spoon to the mouth of the spoon, and the Polaris is about 5 times the distance between the two stars. So people call these two stars "Polaris". In ancient times, when instruments were underdeveloped, people had to rely on instruments to indicate the direction when sailing at sea and traveling in deserts, forests and wilderness. Even in today's advanced science, people need to use them to judge the direction. Ursa major has a very interesting binary star, which is the second-class star in the middle of the bucket handle, and there is a very dark little star next to it. People often check their eyesight by looking at small stars. On a clear night, if you can see with naked eyes, your eyesight can reach 1.5.

If you find Polaris, you will find Ursa minor, which is the brightest star in Ursa minor. In the northern hemisphere, people see that Polaris seems to never move near the north celestial pole, shining with its brilliance and guiding people. Standing in front of Polaris means facing north. Because of the special position and important role of Polaris, small constellations like Ursa minor become very important.