83202
This higher symmetry results from two properties of the Kepler problem : the velocity vector always moves in a perfect circle and , for a given total energy , all such velocity circles intersect each other in the same two points .
 Kepler
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Kepler