Is it normal that when u close your eyes, u see many dots, almost like a galaxy of planets?

Those are pretty normal. They called phosphenes. "... phosphene Use Phosphene in a sentence Ads Terminix® - Pest Control terminix.com Guaranteed Solutions in 24 hours. Get Pests Out. Problem Solved. "Shocking" 2014 Horoscope astrologyanswers.com/Zodiac Enter Your Zodiac Sign to Find Out Your Future. So Accurate its Scary! phos·phene [fos-feen] Show IPA noun Physiology . a luminous image produced by mechanical stimulation of the retina, as by pressure applied to the eyeball by the finger when the lid is closed. Origin: 1870–75; < French phosphène, irregular < Greek phôs light (contraction of pháos ) + phaínein to show, shine Dictionary.com Unabridged Based on the Random House Dictionary, © Random House, Inc. 2014. ..." http://dictionary.reference.com/browse/phosphene

That's most likely your eyelids and some leftover light, don't worry, it's normal.

The human eye is like a hollow globe filled with fluid. Behind the lens, and filling all the posterior portion of the eye, is the Vitreous Humor. It is “normally” a transparent viscous liquid, similar to egg white in consistency. A thin membrane that is attached to the retina contains the vitreous humor. Before the picture is focused sharply on the retina, the light passes through the clear vitreous fluid of the eye, just as the light would pass through the “air” in a camera. The vitreous must always be crystal clear if the eye is to provide crystal clear vision. Any spots in the vitreous will appear as black spots to the viewer.