Which of the following terms is given to a pair of stars that appear to change position in the sky, indicating that they are orbiting one another?
A) spectroscopic binary
B) double star
C) eclipsing binary
D) visual binary
E) none of the above
Question 2
Kepler's first law worked, where Copernicus' original heliocentric model failed, because Kepler described the orbits as
A) much larger than Copernicus had envisioned.
B) complex, with epicycles to account for retrograde motions.
C) around the Sun, not the Earth.
D) elliptical, not circular.
E) being on equants instead of epicycles.