Question

select the word that means a change in belief. scientists once commonly believed that all planets in the solar system traveled in perfect circles. today, however, we know that planets have elliptical, or oval - shaped, orbits around the sun. this shift was the result of work by johannes kepler. kepler was an important scientist in the late 1500s and early 1600s. using mathematics, kepler showed why the shape of planets orbits could not be perfect circles. by tracking the planet mars over two years, he was able to make a model of marss orbit. his work, known as keplers laws of planetary motion, is still taught in schools today.

Explanation:

The passage describes a change in the scientific belief about planetary orbits, and the word "shift" is used to refer to this change in belief. We analyze the context: scientists' belief changed from planets moving in circles to elliptical orbits, and "shift" in the sentence "This shift was the result of work by Johannes Kepler" refers to the change in belief.

Answer:

shift