Chemistry can teach us about the composition of celestial bodies and determine their age.
Scientists, indeed, have found a way to find out which elements are parts of the celestial bodies, and by composition can also get to know their age.
It began with studying the light emitted by burning sodium.
The white-hot solid body gives a continuous seven-color spectrum when its rays are decomposed by a prism. If we pass these rays through sodium vapor, then the spectrum appears to be cut by several black lines. The most noticeable, sodium-specific line cuts the yellow part of the spectrum just where the burning sodium, which casts rays of light through the spectroscope, would give a bright yellow line.
The flame of each element does not give a continuous spectrum, but a discontinuous one, consisting of separate colored bands.
Carefully considering the spectrum of the Sun, stretched in length, they found in it dark lines (Fraunhofer lines), quite exactly coinciding with the lines peculiar to elements
What could this mean other than there is sodium vapor in the solar sphere?
After that, first in the spectrum of the Sun, and then other stars, lines were found that are similar to other terrestrial elements. But in their spectra there are also many such lines that do not correspond to the substances known to us. Some of the scientists even dubbed them in absentia and determined the approximate nature of these extraterrestrial elements by the location of the lines in the spectrum. Such are: helium, corona, nobelium and others. The history of the discovery of helium serves as an excellent proof that such a definition of substances from us at dizzying distances of billions of billions of kilometers is not a simple fantasy, but the greatest achievement of human mind. After it was found by the spectroscope on the Sun, it was found on the Earth. In other words, when a new element was found in terrestrial minerals, its spectral lines coincided with the lines of helium with accuracy. So this was helium! It is found in the waters of some sources, for example, in the Caucasus and the Volga region, and in quantities of 0.000001-0.000002 fraction of volume it is a part of the air.
Celestial bodies are divided according to their spectra into those consisting of hydrogen and other gases, - these are the youngest; then enclosing pairs of metals, - this group is older; and finally, the ones containing carbon are the oldest.
Of course, this "age of stars" depends not only on the time that has elapsed since the day of their formation, but also on their size. The larger the celestial body, the longer it remains "young"; the smaller its mass, the earlier it manages to "grow old."
The same observations on the spectra of stars, and, consequently, on their composition, show us that the 92 elements known to us do not represent the corresponding number of absolutely unchangeable primary forms of matter. Over time, measured, perhaps, by millions of our Earth years, the "hydrogen" stars turn into "metallic" stars. Where do these metals come from? Someday, astronomy, physics and chemistry will jointly solve this problem for us, and we will unravel the mystery of the formation of elements, as they have already begun to unravel the mystery of their structure.
The displacement of the spectral lines of the elements, observed in the study of the spectra of the so-called "fixed" stars, toward the red or violet part of the spectrum indicates the direction of their movement - to us or from us. The magnitude of this displacement makes it possible to determine the velocity of motion of the star.
Here's how a simple experience of burning sodium led scientists to amazing the results.