Light consists of rays that enable us to see something. light rays fall on an object, for example, which sends some of the light rays back again. These light beams then contain important information about the color, the shape of the object and where exactly it is located. Our eyes pick up the light rays and transmit them to the brain. Only then can we see the object.
Without light we can’t see anything at all. Or to put it another way: the more light rays that fall into our eyes, the better we can see. Rays of light are straight. When they hit an object, they are either swallowed, i.e. retained, or reflected, i.e. redirected in another direction. Dark colors can swallow light, light colors reflect more.
Light rays originate from light sources. The brightest light source we know is the sun. It consists of the gases hydrogen and helium and glows so strongly because hydrogen atoms constantly combine to form helium atoms. This produces light and heat.
Until modern times, people still did not know exactly what light was. For example, you thought: You can see through it that rays come out of our eyes. These rays palpate things and go back to the eyes.
What makes the difference in light?
Light rays can be thought of as tiny waves. Waves that are far apart produce red light. If the waves are closer together, yellow light is produced. Then it turns green, blue and violet. These are the colors we humans can see. After violet comes ultraviolet, which is seen by certain animals. If the waves are even further apart than red, this is called infrared. This is what other animals see. Sunlight contains all these colors. They become visible in the rainbow. These colors are called spectral colors.
We can perceive light with our eyes as rather warm or rather cold. Cold light has a short wavelength. It is very white, sometimes with a slight tinge of bluish or purple. Such lamps are marked as "cold-white". "Warm-white" light has longer waves, it is rather yellow. The light of a fire is yellow-orange. That seems warmer to our eyes. But the heat we feel on our skin comes from infrared rays, which we can’t see with our eyes.
But this is only the beginning. Opticians have found that light rays can be thought of as tiny waves. The closest waves result in atomic radiation. X-rays are a little less tight. Then comes ultraviolet radiation, which causes sunburn, for example. Then follow the colors visible to us from violet to red. Then comes the infrared radiation, for example the heat of a fire. Even less dense are the microwaves that warm us up a bit, for example, in a microwave oven. Finally come the radio waves, which transmit us the programs.
What is the speed of light?
Light can propagate incredibly fast. In one second the light covers 300.000 kilometers, which is the equivalent of one billion kilometers per hour. So the light needs only a little bit more than one second from the earth to the moon.
For us humans this speed is not perceptible. For example, when we turn on a lamp, we think the light is instantaneous. However, the speed of light plays a very important role in the exploration of the universe.
What is a light year?
A light year is the length that a ray of light travels in one year. One light year is about ten trillion kilometers. That is a one with 13 zeros. With "light year" one measures therefore not the time, but a distance. Light years are mainly used to indicate large distances in space.
Who speaks of light years, can also calculate other lengths: Light hours, light minutes or light seconds. If the sun suddenly stopped shining, we would only notice it eight minutes later. So the sun is eight light minutes away from the earth. The distance to the moon is a little more than one light second.
From other stars, which we see at night in the sky, the light is many years on the way. Therefore, we do not see the stars as they look today, but as they looked in the past.
Our solar system lies in the Milky Way. It has the shape of a flat disk. At the longest point their diameter is about 200.000 light years.
There is also an article about "light" for reading beginners on MiniKlexikon.en and more search results from Blind Cow and Ask Finn.
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