Answer to Question 1
Shapley began his research on the star system by noticing that, although open star clusters are scattered all along the Milky Way, more than half of all globular clusters lie in or near the constellation Sagittarius. The globular clusters seem to be distributed in a great cloud with a center located in the direction of Sagittarius. Shapley assumed that the orbital motion of these clusters is controlled by the gravitation of the entire star system, and for that reason he concluded that the center of the star system must lie somewhere toward Sagittarius.
Answer to Question 2
Zero Age Main Sequence
The structure of the human ear.
Spitzer Telescope Picture of a galaxy
Spiral Galaxies Seen Nearly Edge On from the Milky Way
Structure of phospholipase A2
Structure of E. coli ribonucleoside diphosphate reductase
Similarity of the chemical structure of 5-bromouracil (5-BU) and thymine