Each body on Earth and in space emits electromagnetic radiation (photons) of different lengths. As at the birth of the Universe and now the radiation of photons - these basic elementary particles, plays a much more significant role than the others.
Elementary particle on Earth
The higher the body temperature, the more photons it emits at a higher frequency. Temperature is a characteristic of a particle in a radiation state.
If photons come into contact with any matter, one of the following phenomena occurs:
- Rays that come into contact with a smooth, shiny surface (e.g. a mirror) are reflected. In doing so, they change their direction without causing any changes in matter.
- When it hits a black rough surface, the rays are absorbed by it. This means that they become the heat of the black matter, which heats up.
- The rays pass through a transparent material, such as glass, without being absorbed by it. But in colored glass, some kinds of rays are absorbed. Only the red photons pass through the red glass, the rest is absorbed, turning into heat.
Reflection of light in different directions is called scattering. It occurs with the help of air molecules and dust. Blue light spreads primarily on air molecules, while red light is hardly scattered in this way. This explains why the sky is blue and the sun is red.
If the rays fall on the surface of transparent matter at an angle, they are refracted. The slower the rays spread in this matter, the more they deviate from their original direction.
If white light, consisting of all the colors of the rainbow, falls on the plane of the glass prism, it refracts. Red light spreads faster in the glass than blue light, so blue light refracts more than red light. For this reason, the white light is expanded into individual colors in the prism. This was discovered in about 1700. Isaac Newton.
The white sunlight decomposed by a prism into color stripes is called the spectrum.
A similar phenomenon occurs with ice crystals in the clouds at high altitudes. At the same time, a beautiful sight appears in the sky - a solar halo. Another example is the decomposition of light during rainfall - rainbow and even double rainbow.
Elementary particle from space
Radiation of photons from stars and other bodies can be very different frequency, this is why there is a spectrograph device that can classify them.
The frequency distribution of photon radiation is called the spectrum of a star.
We can determine not only the star's temperature but also the speed at which it approaches or moves away from us, its chemical composition, speed of rotation, magnitude, mass and amount of energy emitted by the star. We live on Earth because the Sun emits photons. From the nearest stars, elementary particles reach us earlier than from distant galaxies. Thus, the photons that now come to Earth from space are of different ages.
Their age is determined by the remoteness of the body that sent the photon from the surface of the Earth.
The lifetime of radiated photons:
- of the meteors is estimated to be about a thousandth of a second;
- from the Moon, they fly for a quarter of a second;
- from the Sun - eight minutes;
- from close stars - a few years;
- from the center of the Milky Way come to us in thirty thousand years;
- from the galaxy in the constellation of Andromeda in two million years;
- from remote galaxies in a few billion years.
We call the oldest photons fossil. They remember the birth of the universe.
The more distant space we see, especially the night sky, the more distant we look back in time. And all this thanks to the speed of light already known to us. Only our descendants, who will live on Earth in two million years, will be able to learn what is happening now, in our time, for example, in the neighboring galaxy M31 in the constellation Andromeda. That's how many years a beam of light has been flying from the constellation Andromeda to our Galaxy, although we can see it with the naked eye in the autumn sky. In general, it is the most remote visible object in space.