Science Tips Chapter 3

1. Why do we get goose bumps? There are sweat hairs on the surface of our skin, and there is an arrector pili muscle under each pore. When stimulated by nerves (for example, when we are angry, afraid, or cold), the body temperature will drop, and the arrector pili muscle will contract and make the hair stand up, forming goose bumps. In addition to the function of heat preservation, this physiological system can also make the animal's body look larger than it actually is, thereby scaring off the enemy.

2. Is the seahorse born from the father's belly? Almost all animals reproduce the next generation in females, but seahorses are different. They are born in males. There is a brooding sac on the belly of the male seahorse, which is like a kangaroo's "brood pouch". The female seahorse will discharge eggs into the brooding sac of the male seahorse. After that, the male seahorse will take on the responsibility of breeding, and after about three weeks, the baby seahorse will pop out of the father's body.

3. Why do leaves change color? The reason why leaves change color is related to the chemical substance they contain - chlorophyll. When autumn comes, the daytime is shorter than in summer, and the temperature is lower, so the leaves stop making chlorophyll, and the remaining nutrients are transported to the trunk and roots for storage. The leaves lack green chlorophyll, and at the same time, other chemical pigments appear, so we see more yellow and brown leaves.

4. Why do leaves fall? When autumn comes, more water evaporates from the leaves than in summer, but the roots absorb less water than in summer. In order to reduce the water loss of trees, the cells in the stems begin to form a separation layer. After the nutrients completely leave the leaves, the separation layer will isolate the leaves from the trunk, and the leaves will fall off.

5. Why do whales spray water? Whales are a kind of mammal, but their noses do not have nasal shells, and their nostrils grow on the top of their heads. Living in the water, they breathe with lungs, which can store a lot of air at a time, and they do not need to frequently go to the surface to breathe. But when they go to the surface to breathe, they breathe with their noses, and the huge sound waves caused by the seawater spraying out of the body when breathing are caused by pressure.

6. How big is the Milky Way? Many stars come together to form a huge galaxy, and the galaxy where the solar system is located is called the Milky Way. The Milky Way is like a big discus, about 80,000 light years wide and about 12,000 light years thick in the center. The total number of stars is more than 1,000.

7. Why can't we see stars during the day? Because part of the sunlight during the day is scattered by the gas and dust in the atmosphere, making the sky very bright, and the light from the sun is very strong, so we can't see the stars.

8. What celestial bodies are there in the solar system? There are nine planets in the solar system. They are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. In addition, there are many asteroids, comets and meteors in the solar system, and there are 2,958 officially numbered asteroids. The most famous comet is Halley's Comet.

9. How high is the blue sky? "Blue sky" is actually the earth's atmosphere. The atmosphere surrounds the air of the earth. It is divided into 5 layers according to the different air density, with a total thickness of 2000-3000 kilometers. But most of the air is concentrated from the ground to below 15 kilometers. The higher you go, the thinner the air is. The thicker the atmosphere is, the higher the blue sky should be.

10. What is thunder?

Answer: This is a natural phenomenon that occurs when negative electricity and positive electricity meet. When it rains, some clouds in the sky carry positive electricity and some carry negative electricity. When the two clouds meet, they will discharge electricity, emit very bright lightning, and at the same time release a lot of heat, which quickly heats the surrounding air, expands, and makes a loud sound, which is thunder.