Astronomy midterm question: possible IAU classification of "cubewano" 2014 MU69?

Astronomy 210 Midterm 2, spring semester 2019
Cuesta College, San Luis Obispo, CA

A "cubewano" is defined as a Kuiper belt object whose orbit around the sun is not gravitationally controlled by Neptune or other planets[*]. Discuss whether or not a "cubewano" such as 2014 MU₆₉ (nicknamed "Ultima Thule," shown at right[**]) could be considered a dwarf planet, and why. Explain using the International Astronomical Union classification scheme.

[*] wiki.pe/Cubewano.
[**] nasa.gov/sites/default/files/thumbnails/image/ultima-thule-1-ca06_022219.png.

Solution and grading rubric:

• p:
  Correct. Discusses IAU classification scheme to argue that 2014 MU₆₉ would meet qualification I (orbits the sun directly), but with its irregular shape would not meet qualification II (rounded shape), and thus be classified as solar system debris. (Note that as a Kuiper belt object, 2014 MU₆₉ does not meet qualification III (dominates its orbit), but this does not affect its solar system debris classification. But may instead interpret 2014 MU₆₉'s shape is "round enough" in order to conclude that it would be classified as a dwarf planet.)
• r:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors.
• t:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. Explicitly lists IAU requirements, but does not apply them correctly/consistently.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Discussion only tangentially related to the IAU classification scheme.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion unrelated to the IAU classification scheme.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 30676
Exam code: midterm02SpsR
p: 27 students
r: 4 students
t: 5 students
v: 3 students
x: 2 students
y: 0 students
z: 0 students

A sample "p" response (from student 7563):

Astronomy midterm question: possible IAU classification of "twotino" 2002 WC19?

Astronomy 210 Midterm 2, spring semester 2019
Cuesta College, San Luis Obispo, CA

A "twotino" is defined as a Kuiper belt object whose orbit around the sun is periodically perturbed by Neptune's gravity[*]. Discuss whether or not a "twotino" such as 
2002 WC₁₉ (shown at right[**], as depicted by an artist) could be considered a dwarf planet, and why. Explain using the International Astronomical Union classification scheme.

[*] wiki.pe/Twotino.
[**] se-database.fandom.com/wiki/2002_WC19.

Solution and grading rubric:

• p:
  Correct. Discusses IAU classification scheme to argue that 2002 WC₁₉ would meet qualification I (orbits the sun directly), and appear to meet qualification II (rounded shape), but does not meet qualification III (dominates its orbit), it would be classified as a dwarf planet.
• r:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors.
• t:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. Explicitly lists IAU requirements, but does not apply them correctly/consistently.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Discussion only tangentially related to the IAU classification scheme.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion unrelated to the IAU classification scheme.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 30674
Exam code: midterm02nwF7
p: 19 students
r: 1 student
t: 7 students
v: 4 students
x: 2 students
y: 0 students
z: 0 students

A sample "p" response (from student 2815):

Astronomy midterm question: possible IAU classification of "rounded" 2006 RH120?

Astronomy 210 Midterm 2, fall semester 2018
Cuesta College, San Luis Obispo, CA

2006 RH₁₂₀ (previously known as "6R10DB9") is an object that orbits the sun most of the time, but periodically is caught by Earth's gravity to make several loops around Earth, before returning back to its normal orbit around the sun:

Is 2006 RH₁₂₀ a "second moon?" I'd call it a chunk of rock that orbits the sun almost all the time, spending only a few months orbiting Earth in 2006. It will make passes by us in 2028 and 2044 (at safe distances), and every twenty years or so after that. Eventually, it'll get caught for a few orbits around Earth again, and will almost certainly be ejected again, just as happened this time. 2006 RH₁₂₀ quite likely got where it is as a result of being blasted off the surface of the moon by an impact.[*][**]

In the (unlikely) event that 2006 RH₁₂₀ is found to have a rounded shape, discuss how it should be classified when it is in its usual orbit around the sun. Explain using the International Astronomical Union classification scheme.

[*] projectpluto.com/pluto/mpecs/6r1.htm.
[**] Illustration credit: Gregg Dinderman, skyandtelescope.com/astronomy-news/earths-other-moon/.

Solution and grading rubric:

• p:
  Correct. Discusses IAU classification scheme to argue that 2006 RH₁₂₀ when in its usual orbit around the sun would pass qualification I (orbits the sun directly), and with a presumably (however unlikely) rounded shape would pass qualification II (rounded shape), but as it is periodically captured by Earth's gravity 2006 RH₁₂₀ does not dominate its orbit, and thus would presumably be classified as a dwarf planet.
• r:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors.
• t:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. Explicitly lists IAU requirements, but does not apply them correctly/consistently.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Discussion only tangentially related to the IAU classification scheme.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion unrelated to the IAU classification scheme.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 70158
Exam code: midterm02SYnR
p: 29 students
r: 0 students
t: 0 students
v: 4 students
x: 0 students
y: 1 student
z: 1 student

Section 70160
Exam code: midterm02NdI0
p: 6 students
r: 2 students
t: 6 students
v: 3 students
x: 1 student
y: 0 students
z: 0 students

A sample "p" response (from student 4073):

Astronomy midterm question: plausible IAU classification of 300163 (2006 VW139) before breaking apart?

Astronomy 210 Midterm 2, fall semester 2017
Cuesta College, San Luis Obispo, CA

An international team of astronomers recently discovered two asteroids with comet-like features orbiting each other in the asteroid belt:

NASA's Hubble Space Telescope helped an international team of astronomers find that an unusual object in the asteroid belt, designated 300163 (2006 VW139), is in fact two asteroids of almost the same mass and size, orbiting each other at a distance of 60 miles. They also have comet-like features, including a bright halo of material, called a coma, and a long tail of dust. Roughly 5,000 years ago, 300163 (2006 VW139) probably broke into these two pieces due to a fast rotation.[*]

Before it broke apart 5,000 years ago, discuss how 300163 (2006 VW139) might have been originally classified, using the International Astronomical Union classification scheme. Clearly state your assumptions about what properties 300163 (2006 VW139) might have had before it broke apart.

[*] J. Agarwal, "Comet or Asteroid? Hubble Discovers that a Unique Object is a Binary," hubblesite.org/news_release/news/2017-32.

Solution and grading rubric:

• p:
  Correct. Discusses IAU classification scheme to argue that before breaking up 5,000 years ago:
  1. 300163 (2006 VW139) was in the asteroid belt, orbiting the sun, and thus could not have been a moon; and not having been able to gravitationally dominate its orbit by clearing asteroids out or pulling in asteroids into itself, could not have have been a planet (assuming that it had a rounded shape); and
  2. depending on whether its shape was irregular or rounded, it would have either been classified as solar system debris or a dwarf planet.
• r:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. May have instead discussed how the two components of 300163 (2006 VW139) today could be categorized in terms of the IAU classification scheme, instead of how it might have been categorized before breaking up 5,000 years ago.
• t:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. Explicitly lists IAU requirements, but does not apply them correctly/consistently.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Discussion only tangentially related to the IAU classification scheme.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion unrelated to the IAU classification scheme.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 70158
Exam code: midterm02Sm5n
p: 35 students
r: 4 students
t: 5 students
v: 2 students
x: 0 students
y: 0 students
z: 0 students

Section 70160
Exam code: midterm02nJv3
p: 23 students
r: 5 students
t: 3 students
v: 0 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 0987):
Another sample "p" response (from student 1796):
A sample "r" response (from student 1881), discussing the current classification of 300163 (2006 VW139) today:

Astronomy quiz question: meeting the first IAU classification qualification

Astronomy 210 Quiz 4, spring semester 2014
Cuesta College, San Luis Obispo, CA

Listed below are 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.

Qualification I is met by:
(A) planets.
(B) dwarf planets.
(C) moons.
(D) asteroids.
(E) (More than one of the above choices.)
(F) (None of the above choices.)

Correct answer (highlight to unhide): (E)

Qualification I would be met by planets, dwarf planets, and asteroids, as they all directly orbit the sun. Moons would be the only item in this selection that do not directly orbit the sun (as they would orbit their planets or some other central body instead).

Section 30674
Exam code: quiz04n6rD
(A) : 1 student
(B) : 0 students
(C) : 4 students
(D) : 4 students
(E) : 16 students
(F) : 0 students
(No responses : 1 student)

Success level: 64% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.36

Section 30676
Exam code: quiz04snr7
(A) : 1 student
(B) : 0 students
(C) : 2 students
(D) : 4 students
(E) : 32 students
(F) : 0 students

Success level: 83% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.45