Re: Why do some stars form in constallations and some do not?

Question: Why do some stars form constellations and others don’t?

We are living in the Milky Way galaxy that has hundred billion stars in 
it.  These stars all are at different distances from us.  Here on Earth, 
when we look up into the sky, it appears to us that all the stars are 
located on a hemisphere.  As we look at into the sky at all of these stars 
(we can see several thousand with the naked eye), they appear to make 
patterns. These patterns are called constellations. But not all of the 
stars, especially the fainter ones, are incorporated into the patterns. 
Different cultures throughout history have made patterns/constellations of 
the stars and told stories about them. In ancient times people thought the 
stars were gods and making patterns of the stars, allowed them to make 
offerings to them and talk with them. The constellations that we today 
talk about like the Big Dipper (Ursa Major), Orion, Scorpio etc. were made 
thousands of years ago by the Babylonians and came to us via the Greeks.  
Other cultures made up different patterns of the stars and told different 
stories.  The ancient Egyptians showed the Big Dipper as the hind leg of a 
cow.  The Chinese talked about the Big Dipper as officials of the court 
talking to their emperor. The South Sea Islanders called the constellation 
of Scorpio a palm tree.

People have made up constellations to help them remember what is in the 
sky and help them to tell time at night.  So only the obvious stars 
(usually the brighter stars) were made into constellations.

Reference: M. Seeds, FOUNDATIONS OF ASTRONOMY, 4th ed, 1996
Julius Staal, THE NEW PATTERNS IN THE SKY, Myths and Legends of the Stars, 
1988