Why star is the most beautiful? (图)

Both form of Chinese number and Arabic number are meaningful. Chinese is more close to human life, and maybe for bull and bear thinking.  Why five-pointed star is the most beautiful one among other numbered? 
By the way compare the national flag of Soviet Union and China, the former has smaller star than hammer and sickle, even though the star is gone now, while the later is in the opposite way, this is another example of Chinese tradition.