1. Why do the stars twinkle?

We see the stars shining, not because the luminosity of the stars has changed, but because of the occlusion of the atmosphere.

The atmosphere is between us and the stars. When starlight passes through the atmosphere, it will be affected by the density and thickness of the atmosphere. The atmosphere is not absolutely transparent, and its transparency will change according to its density. So when we look at the stars through it on the ground, we will see that the stars seem to be flashing.

2. Why can snakes walk without feet?

Snakes have many scales, which are the outermost armor on their bodies. Scales are not only used to protect the body, but also to be their "feet".

When a snake crawls forward, its body will be S-shaped. Every scale outside the S-shape will tilt upward to help the snake catch the uneven road when it moves forward. These scales cooperate with the muscles of the snake and can push the body forward, so the snake can walk without feet!

3. Why do sunflowers always bloom towards the sun?

There is a substance called "auxin" in the stem under the sunflower disk. This substance has the function of accelerating replication, but it is anti-optical, and it will run to the backlight side whenever it encounters light.

So when the sun rises, the stem of the sunflower immediately hides to the side of the backlight, as if the whole plant is bent in the direction of the sun.

4. Why do people yawn?

When we feel tired, a lot of carbon dioxide has been produced in our bodies. When there is too much carbon dioxide, oxygen must be supplemented to balance the needs of the body. Because these residual carbon dioxide will affect our body's functional activities, then the body will send out a protective reaction, so we yawn.

Yawning is a deep breathing action, which will let us breathe in more oxygen and expel more carbon dioxide than usual, and it can also eliminate fatigue.

Science and technology festival slogan:

1, solve the mystery, very clever. Believe in science and defeat SARS. Between heaven and earth, innovation is infinite.

2. Try to explore and solve the mystery. Scientific and technological creation, beyond dreams. Science, flying dreams.

3. Pay attention to science and technology and create legends. Technology is gold. There is no end to science and innovation.

4. Go into science, overcome SARS, explore mysteries and pursue truth. Advocating science and creating the future.

5, love science, people have confidence, work hard to create, and eventually become great instruments, scientific and technological innovation, endless.