As country attaches great importance to science and technology and constantly increases investment in various scientific research, demand for scientific and technological talents is also great.
Influencing level of education, schools are also paying more attention to development of science courses, and more and more schools are paying more attention to scientific knowledge in teaching process.
The editor specially brings these 30 little scientific knowledge, parents should collect them for their children.
1. Why do stars twinkle?
We see stellar flares not because of changes in brightness of stars themselves, but because of occlusion of atmosphere. The atmosphere is between us and stars. As starlight travels through atmosphere, it is affected by density and thickness of atmosphere.
Atmosphere is not completely transparent, its transparency will vary with density. Therefore, when we look through it at earth at stars, we see that the stars seem to twinkle.
2. Why do sunflowers always bloom towards sun?
The part of stem below disk of a sunflower contains a substance called "vegetable auxin". This substance has function of accelerating reproduction, but it has an anti-rotation property: every time it encounters light, it goes to side that is not lit.
Therefore, when sun rises, sunflower stem immediately hides on illuminated side, and it seems that whole plant leans towards sun.
3. Why do fireflies glow?
Fireflies will glow because they have a light emitter at end of their abdomen, filled with a variety of phosphor luminescent substances and luminescent enzymes, so that fireflies can emit flashes of light.
The light of a firefly is intended not only for illumination, but also for courtship, warning, trapping and other purposes. It is also a tool for their communication. Different types of fireflies have different methods of emitting light, frequencies and colors of emitting light, and they use this to convey different messages.
4. Why is sea water mostly blue and green?
When looking at sea, I often find that sea water is blue-green. However, when you scoop up sea water, all you see is that it is as clear and colorless as water was in past.
It turns out that sea water itself is not much different from water we come into contact with every day, and it is also transparent. The green color we see is actually a phenomenon caused by ability of seawater to absorb light. Only green light can be absorbed by seawater and reflected; when sea water is deeper, green light is also absorbed and sea water looks blue.
5. Why do leaves change color?
The reason leaves change color is due to chemical they contain, chlorophyll. When autumn comes, daylight hours are shorter than summer and temperatures are cooler, so leaves stop producing chlorophyll and remaining nutrients are transported to trunk and roots for storage.
Leaves lack green chlorophyll, while other chemical pigments appear, so we see more yellow and brown leaves.
6. Why does sorbet smoke?
Sorbet smokes because there is a lot of invisible water vapor in outside air. When it encounters a very cold sherbet, it turns into mist and surrounds sherbet when it is cold. It seems that sorbet "gassing" "The same.
7. Why do people yawn?
When we feel tired, body produces a lot of carbon dioxide. When there is too much carbon dioxide, oxygen must be added to balance body's needs. Since this residual carbon dioxide will affect functional activities of our body, at this time the body sends a defensive reaction, so we yawn.
Yawning is a deep breathing action that will allow us to take in more oxygen and expel carbon dioxide than usual, as well as eliminate fatigue.
8. Why do you have goosebumps?
There are fine hairs on surface of our skin, and under each pore there is a muscle that straightens hairs. It shrinks and makes hair stand up, forming goosebumps.
In addition to keeping warm, this physiological system can also make an animal appear larger than it actually is, thereby scaring off enemy.
9. The seahorse was born from womb of father?
Almost all animals also reproduce females, but seahorses are unusual in that they are born males. The male seahorse has a kangaroo-like egg sac on its abdomen, and female seahorse releases eggs into male seahorse's egg sac.
After that, male seahorse takes over responsibility for reproduction, and after about three weeks, a baby seahorse emerges from father's body.
10. How big is Milky Way?
Many stars combine to form a huge galaxy, and galaxy in which solar system is located is called Milky Way. The Milky Way is like a large disk, about 80,000 light-years wide and about 12,000 light-years thick at center, with a total of over 1,000 stars.
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