عنوان مقاله [English]
Astronomical reflections are indeed stories of astronomical optical (visible through emitting light) bodies which are extinguished, leaving behind only a nice memory. In this chapter, we deal with a type of telescope-based astronomy which is not possible to practice with naked eyes.
It concerns the images of nebulae, a continuous and attractive cloud which indicates the presence of dark objects in space which we are not aware of. First astronomers equipped with telescope observed unclear and expanded objects among the stars which they named nebula (Latin word for dark parts of clouds). Even before telescope, the Andromeda nebula and Magellanic Clouds had been observed by naked eyes as enigmatic permanent spots with a weak light. An example of the most famous and largest nebulae-like or expanded forms is the Milky Way. This galaxy is very ambiguous, and has been a mystery for long. However, these dark and ambiguous shapes in nocturnal sky were gradually classified into two separate parts. These are the same masses which radiate light and heat due to high temperature of atoms that constitute them. The best example of such radiations is the Sun’s ray and other stars and objects formed by stars, such as the Milky Way and other galaxies and spherical star clusters.