What season is the Big Dipper pointing south?

Because there are many stars in the sky, most of them are stars (basically invisible in the sky), and there are about 6,000 stars that can be seen by the naked eye. The vast Xinghai often makes many people sigh, and they don't know how to recognize the stars. In fact, it is not difficult to make friends with stars. First of all, we need to understand how the star regions are divided. Just like knowing your best friend, you should know his home address and the environmental characteristics around his home. The division of stellar sky region is equivalent to the division of blocks. In ancient China, the starry sky was divided into three walls and twenty-eight houses. Accommodation is living. Divide the stars outside the accommodation into three walls: Wei Zi wall, Taiwei wall and Shi Tian wall. Wall means wall. It means an area of stars surrounded by walls. (slide show)

The ancient Babylonians divided the sky into many regions called "constellations", and each constellation was identified by the special distribution of bright stars. The ancient Greeks divided the visible part of the sky into 48 constellations around 270 BC, connected the main bright stars in the constellations with imaginary lines, imagined them as people or animals, and gave them appropriate names in combination with fairy tales. This is the origin of the constellation name. (Showing pictures of various constellations) 1928, the International Astronomical Union decided to divide the whole day into 88 star zones, called constellations. Among these 88 constellations, there are 12 constellations along the ecliptic. They are Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn and Aquarius. There are 29 constellations in the north and 47 constellations in the south.

Because there are more than forty constellations in Greek mythology living in the northern sky and north and south of the equator, they are just our common constellations. As long as you remember the positions and names of these constellations and their relationships with other constellations around you, and remember the imaginary pictures connecting the main bright stars, you can easily identify the whole starry sky.

Look at the picture on page 98 of the textbook (1, do you know the following constellation? Please find them in the map) (Show pictures of Ursa Major, Ursa Minor, Cassiopeia, Aquila, Lyra, Orion and Cygnus)

Explanation: The southern constellation was gradually determined after the successful voyage around the world in the17th century, and then observed by navigators, so there were many advanced scientific instruments to name the southern constellation at that time. Such as telescope base, compass base, microscope base, compass base, etc. The more striking bright stars are the "big men" among the stars, and people have given them names.

Look at the picture (2. Find the following stars) (Polaris in Ursa minor, Vega in Lyra, Altair in Eagle, Sirius in Canis major, the brightest star in the whole day. Show pictures)

(Slide and show the following text) For many stars, in 1603, Johann, a German amateur astronomer, proposed a naming method: the stars in each constellation are arranged in order from light to dark, and the constellation names are expressed in Greek alphabetical order. Such as Orion α (Betelgeuse), Orion β (Betelgeuse), Orion γ (Betelgeuse) and Orion δ (Betelgeuse). If the number of stars in a constellation exceeds 24 Greek letters, use the constellation name followed by Arabic numerals, such as cygnus 6 1, Scorpio 17. Nowadays, large telescopes and new observation technologies are constantly emerging, and more and more stars are observed. Astronomers, like managing household registration, register one by one and compile a catalogue. The numbers in the catalogue are the same as the names of celestial bodies. Astronomers can aim telescopes at celestial bodies according to the coordinates recorded in the catalog.

Narrator: Please tell me what you know about fairy tales about constellations and stars. (。 Stories such as The Cowherd and the Weaver Girl, The Seven Fairys Descending from Earth are very popular and touching myths about the stars in China.

Question: What's the use of knowing the starry sky?

The student replied: When you get lost in the wild at night, you can look for the North Star.

The teacher added: Because the mutual position of the stars looks unchanged, they appear in different directions in the sky at different times with the rotation and revolution of the earth. Ancient navigators could determine their course by observing the positions of nine selected stars in the sky ("Nine Navigational Planets"). Contemporary interstellar navigation is also guided by stars. Apollo 1 1 The manned moon landing spacecraft used optical locators to locate the stars and ensure that the spacecraft would run along the established orbit. Knowing the stars can also determine the time. For example, around 20 o'clock on New Year's Eve, Orion's "Samsung" is just in the southern sky. Ancient Egyptians could predict whether the Nile would flood by observing the starry sky. People in the Yin Dynasty in China could know whether to start sowing by observing the stars.

The teacher said: How to find the North Star? Please see the textbook 100 for observation. Because the North Star is not very bright and difficult to find, the first step is to find the Big Dipper. The Big Dipper forms a bucket shape in the sky, which is easy to recognize. Its bucket handle is observed at eight or nine o'clock in the evening in different seasons. Bucket handle faces east in spring, bucket handle faces south in summer, bucket handle faces west in autumn and bucket handle faces north in winter. (The teacher teaches the formula: spring, summer, autumn and winter correspond to the southeast and northwest) Step 2, connect the first two stars of the Big Dipper and extend it to the bucket for about 5 times to find the North Star.

According to the teacher's explanation, please draw a schematic diagram to show how to find the North Star. (Teachers show students' sketches under the projector and evaluate them)

The teacher asked: If you get lost in the wild, what other ways can you tell the direction? Ask the students to discuss. Such as compass, watch and sun. )

Do the exercise on page 103, the first question 1: Draw the following constellations. (Ursa major, Ursa minor, Lyra, Orion)

(second class)

Question: Why does the sun rise in the east and set in the west?

The student replied: Because the earth rotates from west to east around its axis, the sun rotates from east to west (rising and setting in the west) relative to the earth.

(If students don't understand this problem, the teacher can give an example to explain it: Just like people sitting in a Mercedes-Benz train and seeing houses and trees running backwards outside, the earth rotates once a day around its axis from west to east, and people on the earth will see the sun rotate once a day around an axis from east to west.

Question: Where does the moon rise and set? A: East rises and west falls.

Question: When you look up at the stars in the sky, do you notice that the stars rise and set in the west like the sun?

After-class observation: Everyone is familiar with the rotation of the sun and the moon. Please choose a constellation with obvious characteristics in the night sky after dark and remember its position in the sky. We'll see in an hour. What did you find? Please write it down. This constellation moves about 15 degrees in the sky. ) display 108 page. This picture is a starry sky photo taken by continuous exposure at night. The exposure time is about 3 hours. The trajectory of the stars in the sky is arc, and its center is Polaris.

Teacher's explanation: students know that the earth revolves around the sun and also around the earth axis. There is an idiom called "Fighting the Stars", in which "Fighting" refers to the Big Dipper. Originally meant to refer to the change of the position of the stars, now it refers to the change of seasons or time. This also shows that the starry sky we see changes with time. In fact, the change of the starry sky involves two kinds of movements of the earth: one is that the earth rotates around its axis, which causes the Sunday change of the starry sky, that is, on the same day, the starry sky changes with hours; Second, the earth revolves around the sun, which causes the annual change of the starry sky, that is, the starry sky changes with the seasons at the same time. According to China's ancient books, "bucket handle refers to the east, and the world is spring; Bucket handle guide, the world is summer; Bucket handle refers to the west, and the world is autumn; " The handle of the bucket points to the north, and it is winter all over the world. That's what this phenomenon means. If you are interested, you may wish to observe this change of Beidou bucket handle, but remember, you must observe it around 8 o'clock every night.

The teacher added that observers at different geographical latitudes see different apparent motions of the starry sky on Sunday: the paths of apparent motions of stars seen by people at middle latitudes tend to rise and fall. The higher the geographical latitude, the smaller the tilt angle, and the observer of the North Pole will see that all the stars are running parallel to the horizon. On the contrary, the lower the geographical latitude, the greater the inclination between the route of the star's apparent motion on Sunday and the horizon. On the equator, the observer will see that all the stars rise and fall vertically. The starry sky area with Polaris as the center and local latitude arc length as the radius can be observed all year round. The corresponding starry sky area centered on the south pole of the celestial sphere will never be seen. The equator can observe the starry sky all day and is an ideal place to establish an observatory. You can only see half the starry sky at the pole forever.

The teacher explained: The stars are far away from us. They all seem to be located on a huge sphere. We call this imaginary sphere the celestial sphere. The earth is the center of the celestial sphere. In fact, different stars are at different distances from the earth. For example, the Big Dipper consists of seven stars that are roughly in the same direction but at different distances from the earth. The position of the stars we see is only a projection effect. (Projection experiment demonstration of the position of the Big Dipper in the sky)

The teacher said: since all the geographical things on the earth's surface can be simplified into maps, we can also draw a star map, which simply shows the positions of constellations and stars in the sky. Using active star map to find constellations and stars. Some stars are bright, others are dark, and the brightness of stars can be expressed by magnitude. The smaller the magnitude, the brighter the star. A 6-magnitude star is the darkest star visible to the naked eye. The brightness of the sun is -26.7 magnitude, the brightness of the full moon is about-12 magnitude, and the brightness of Venus at its brightest is -4.6 magnitude.

1. When observing on the first side of the activity map, find the hour and minute (time) of the corresponding time, such as 2 1: 20.

2. Align the observation time on the first side of the active star map with the observation date on the second side (e.g.165438+1October 20th). We got the local map of1October 20th 165438+2 1: 20.

Please note here: (slide) When looking at the map, we face the earth, and the direction is determined to be up north and down south, left west and right east. When looking at the star map, we are facing the starry sky (that is, the sky). At this time, the direction is up north and down south, and Zuo Dong is due west. Teachers can let five students stand on the stage in different directions to simulate the direction, so that students can understand that the orientation on the map is north and south, and Zuo Dong is due west)

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Compared with the star map, the teacher instructed to analyze the starry sky at 22 o'clock on March 20 (show the star map at this time) (point out the main constellations and first-class bright stars)

The starry sky on a spring night is charming. North of the zenith, Ursa major is on the meridian circle, the Big Dipper is high in the sky, almost close to the zenith, and bucket handle points to the east. Therefore, in ancient China, there was a saying that "the handle of the bucket points to the east and the world is spring". Connect the two stars (β and α) at the mouth of the bucket and extend them five times apart, and you will find the brighter Polaris (α in Ursa minor); Extending along the curves of several stars (δ, ε, ζ, η) in the barrel handle, we can find that arcturus, the brightest (α) star in Capricorn, shines orange in the eastern sky. Double the curve of Beidou bucket handle from arcturus, and you can find another bright star-Jiaokou, which is Virgo Alpha.

Looking south, the majestic Leo is in the sky. It is the center of the starry sky on a spring night. It has a sickle head, a triangle tail and a lion head. Its brightest (α) star is called Xuanyuan XIV.

The starry sky at 22 o'clock on June 20 (showing the sky map at this time) (pointing out the main constellations and first-class bright stars)

The Milky Way in summer night spans the north and south, and it is magnificent. The most striking thing is several constellations in the Galaxy Belt. Vega Milky Way Altair shines on both sides of the Milky Way. Vega is the alpha star of Lyra, and Altair, also known as Crest II, is the alpha star of Aquila. The Milky Way in summer is extremely magnificent, but it can only be seen in the wild without light interference.

In the northern sky, the Big Dipper of Ursa Major is in the air in the northwest. Bucket handle guide rail. You can find Polaris by extending the connection between Beidou-2 (β) and Beidou-1 (α). Polaris is Ursa minor (α). All the constellations that appear in the starry sky of the four seasons revolve around it year after year.

In the center of the southern sky is a huge and striking Scorpio, which appears in the summer night sky. This constellation consists of a dozen bright stars, a scorpion with its head facing west and its tail facing east.

From Altair to the south along the Milky Way, you can find Sagittarius, of which six (μ, λ, φ, δ, τ, ξ) make up the "Southern Dou Six Stars", which is far opposite to the Big Dipper in the northwest sky. The Milky Way in Sagittarius is the widest and brightest. Because this is the direction of the center of the galaxy.

The starry sky at 22 o'clock on September 20 (showing the sky map at this time) (pointing out the main constellations and first-class bright stars)

"Flying horse in the sky, the Milky Way hanging obliquely" is a symbol of the starry sky in autumn. Bucket handle of Beidou refers to the west, but it is not easy to see near the northern horizon. Patrol the autumn starry sky, you can start from the "autumn quadrangle" (also known as "flying horse-fairy box") in the direction of the head. This quadrilateral is like a square. When it is overhead, its four sides just represent one direction. The quadrangle in autumn is made up of three bright stars in Pegasus (α, β, γ) and one bright star in Andromeda (α), which is very eye-catching. Extend the east side line of the quadrangle to the northern sky (that is, from Gamma Pegasus to Alpha Andromeda), and find Polaris through W-shaped Cassiopeia.

The starry sky at 22 o'clock on September 20 (showing the sky map at this time) (pointing out the main constellations and first-class bright stars)

The starry sky is magnificent in winter! The most famous Orion in the whole day is the center of the winter night sky, surrounded by many bright constellations, forming a dazzling starry sky pattern.

The position of the milky way in winter night is just the opposite of that in autumn night. The sky hangs obliquely from southeast to northwest, and the famous big dog, Orion, Gemini, Taurus, Auriga, Perseus and Fairy Queen are arranged around the Milky Way in turn from southeast to northwest.

The first-class star Capella Auriga (α) is close to the zenith, emitting bright light in the sky.

The most striking thing is, of course, Orion hanging high in the southern sky. It is composed of four stars, α, γ, β and κ, and is imagined as a brave hunter. Samsung (Orion δ, ε, ζ) sandwiched between red bright star Betelgeuse (Orion α) and white bright star Betelgeuse (Orion β) is quite attractive, and it is called Samsung in China. Not far below Samsung, there is a gas nebula visible to the naked eye, which is the famous Orion nebula.

Looking south and east along Samsung, you can find Sirius (Alpha Canis), the brightest star in the whole day.

Students discuss: What constellations can be observed in the local area all year round?

After-class observation: The textbook P 10 1 Page observation 1 is used to observe the local starry sky.

The teacher explained: (slide show) looking for the starry trilogy;

Time: Choose a clear moonless night, because "there are few stars on the moon".

Location: Choose a place with a wide field of vision and avoid the lights as much as possible.

1. First, Polaris was found in the sky 30 degrees north of the horizon.

2. Find the famous constellation near Polaris by comparing the star maps.

3. Take this as the "base area" and gradually expand the search scope, every little makes a mickle.