Types of spectra

Please, leave a ray of sunlight through a prism, we obtain the third type of spectrum, to the naked eye it looks identical to the continuous spectrum of solids and liquids, but has a weak telescope can observe in it a few black lines and the study of the solar spectrum at very high magnification shows that he was suspended by a number of such lines. This phenomenon observed Wollaston, the exact same study it did Fraunhofer in Munich, chief of the dark lines of the solar spectrum, he noted the letters of the alphabet from A to H, between the lines, he noticed a number of others. Further, he showed that in the spectrum of the Moon and Venus are observed dark lines are the same as in the solar spectrum, on the contrary, the spectrum of the fixed stars is not all dark lines coincide with lines of the solar spectrum. Fraunhofer has already observed that the dark line of the solar spectrum, denoted by the letter D, is located on-site sodium line, but this important discovery was ignored, and only after 40 years it served as a starting point for wonderful research Kirchhoff. Noticing, in turn, a complete coincidence Fraunhofer line D with a line of sodium, he sought to explain this fact. It is known that a weak flame, being faced with a very bright light source casts a shadow of himself, if, for example, place a lighted candle in front of an electric lamp, there will be a shadow not only on the candles, but also from the flames. Before the slit of the spectroscope Kirchhoff raised slightly luminous flame of sodium, and behind - the source with a bright white light rays are the last on the way to the prism had to go through pre-pale flame of sodium, something happened, what to expect a scientist: got quite a continuous spectrum, only the yellow of his side, where is the line of sodium, or line D of the solar spectrum, was pronounced double dark band. Next, Kirchhoff between the slit of the spectroscope and a source of bright light, place a weak flame lithium immediately on the site of lithium lines in the spectrum appeared the black bars, and the same was repeated with all other bodies, which were investigated in this manner. Thus the line given by the weak flames are black, as just behind him is placed a strong source of light the flame absorb those rays that itself emits, hence it followed that any gas makes the dark lines in the spectrum, if behind it will be a source of bright and constant light.