With the help of this celestial planisphere, one can imagine the daily movement of the stars and the Sun anywhere on Earth and on any day of the year. For example, how will the diurnal movement of stars occur in Petrograd?
To do this, you only need to put the world axis PP1 on the planisphere obliquely to the horizon at an angle equal to the latitude of the place.
For this case we have: the latitude of Petrograd is north, equal to 60њ; therefore, for an observer in Petrograd, it is necessary to give the axis of the world on the celestial planisphere an inclination of 60њ to the horizon. Then the celestial planisphere will show us that all the luminaries of the northern hemisphere will be visible in Petrograd, and from the southern hemisphere only those luminaries whose declination will be from 0њ to -300.
Luminaries with a declination south and equal to -30њ will appear only at the point south and are visible only for one moment.
Luminaries with a negative declination and an absolute value greater than 30њ will be invisible in Petrograd. The luminaries passing through the zenith in Petrograd will have a declination of + 60њ.
Luminaries whose declination is northerly and greater than + 30њ will be non-setting luminaries.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.