Notes on the school textbook of astronomy #003
In some cases, it can hardly be justified to provide ready-made formulas to students. The author had to resort to this, following the program and the set volume of the textbook. The derivation of formulas, as is known, contributes, on the one hand, to the development of logical thinking, and, on the other, to a deeper understanding of it and better memorization. The finished formula is perceived dogmatically by the students. On page 95, the formula for absolute magnitude is derived, and the formula for luminosity is given in a ready-made form. Meanwhile, the derivation of the formula for luminosity is simple and requires only a few lines.
In the section on comets on page 84, it says that "meteors appear to come from a single location called the meteor shower radiant." Students can understand that all meteors in the firmament have only one radiant.
The section on variable stars and new stars contains so much information on two or three pages that, in our opinion, the availability of this material for studying in two or three lessons is very doubtful. Some information is presented very concisely. For example, several lines on cepheids include the light change curve, changes in spectral class, fluctuations in radial velocity, and the period—luminosity relationship, etc.
Similar remarks are suggested for the section on the most important patterns of stellar characteristics. Here, on one page, the dependencies "mass — luminosity", "radius — luminosity" and the "color — luminosity" diagram are outlined. Describing the latter, the author points out that spectral classes or the corresponding logarithms of temperature or color are deposited along the abscissa axis. But spectral classes are not mentioned in the textbook in accordance with the program, so the designations 05, VO, AO, etc. in Fig. 88 will remain misunderstood by students. Here again, the conciseness of the presentation turns out to be deceptive. This paragraph alone requires a separate lesson, or even two, for detailed explanations of the essence of the "color—luminosity" diagram. And, in general, should these dependencies be given in the form of formulas in secondary school?
We cannot blame the author for the fact that the issues of spherical and practical astronomy are clearly insufficiently covered. In this regard, he did more than he could, since the new program almost completely eliminates these sections. A whole series of beautifully executed drawings on spherical astronomy does not have proper explanations in the text, and the desire to compress the text of this part of the course to the limit leads to the fact that some provisions cannot be considered acceptable. So, on page 20 It is said that the Sun rotates in 365 days against the background of the starry sky. Such rounding can hardly be justified in the 10th grade, where it would not be superfluous to emphasize that the year and day are incommensurable. Real free porn movies https://exporntoons.net online porn USA, UK, AU, Europe.
