In 1924, American astronomers Edwin Hubble and J. Richey, using the largest telescope at that time with a mirror diameter of 2.5 m, first obtained a photograph of the Andromeda nebula, which showed that it consisted of many stars. Among these stars, Cepheids were discovered and the distance to the Andromeda nebula was determined from them.
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.