20191017

Astronomy quiz question: transient IAU classification of 2004 EW95

Astronomy 210 Quiz 4, spring semester 2019
Cuesta College, San Luis Obispo, CA

Refer below to the minimal qualifications established by the International Astronomical Union for a planet:
I. Orbits the sun.
II. Shape "rounded-out" by gravity.
III. Cleared/dominates orbit around sun.
2004 EW95 is an object that is in orbit around the sun, currently located in the Kuiper belt[*]:
At first the astronomers thought it was a mistake. They had found an irregular-shaped asteroid floating in the Kuiper belt in 2004. The newly discovered space rock, which they named 2004 EW95, was something the scientists would have expected to have seen in the asteroid belt...
     The pieces of evidence led the team to conclude that 2004 EW95 was formed in the inner solar system, and had most likely been hurled to the outer solar system as the giant gas planets, Jupiter and Saturn, migrated away from the sun.
According to the IAU qualifications, in the past when 2004 EW95 had an orbit in the asteroid belt, it would have been classified as:
(A) a moon.
(B) solar system debris.
(C) a dwarf planet.
(D) a planet.
(E) (None of the above choices.)

[*] Nicholas St. Fleur, "Lost in Space: An Asteroid Strayed From Its Companions," New York Times (May 14, 2018), page D2, nyti.ms/2KPKh3i.

Correct answer (highlight to unhide): (B)

When 2004 EW95 had its original orbit in the asteroid belt, it would have passed qualification I; but since it does not have a spherical shape it would fail qualification II, and would then have been classified as solar system debris.

Section 70158
Exam code: quiz04S3re
(A) : 3 students
(B) : 23 students
(C) : 1 student
(D) : 1 student
(E) : 2 students

Success level: 79% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.11

Section 70160
Exam code: quiz04NDme
(A) : 1 student
(B) : 11 students
(C) : 6 students
(D) : 2 students
(E) : 3 students

Success level: 49% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.83

No comments: