Astronomy 210 Quiz 2, Fall Semester 2009
Cuesta College, San Luis Obispo, CA
Why are some solar eclipses annular rather than total?
(A) The orbit of the moon around Earth is tilted with respect to the orbit of Earth around the sun.
(B) The orbit of the moon not a perfect circle, but is an ellipse.
(C) The moon rotates such that it always keeps the same side facing Earth.
(D) The direction of Earth's axis precesses over a 23,000 year cycle.
Correct answer: (B)
During a total solar eclipse, the moon blocks the entire sun, when observed from within the umbral shadow spot on Earth. However, due to the elliptical orbit of the moon, it may be unable to completely block the entire sun as seen from Earth, due to its distance from Earth being too far.
Response (A) explains why a total solar eclipse does not occur every time the moon is new. Response (C) explains why the near side of the moon is constant; response (D) is the reason why Polaris will not always be the pole star.
Section 70160
(A) : 25 students
(B) : 16 students
(C) : 0 students
(D) : 1 student
Success level: 43% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.82
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment