Pluto Debate Write-Up

Homework 1- Birth of Planets

Marjorie A. Chan PhD and Julia Kahmann-Robinson PhD, University of Utah Department of Geology and Geophysics

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Pluto and its three largest moons as seen by the Hubble Space Telescope. Image Credit: NASA, ESA, H. Weaver (JHU/APL), A. Stern (SwRI) and the HST Pluto Companion Search Team (image found here:http://www.nasa.gov/mission_pages/hubble/plutos_moons.html).

Provenance: NASA, ESA, H. Weaver (JHU/APL), A. Stern (SwRI) and the HST Pluto Companion Search Team. Image found here: http://www.nasa.gov/mission_pages/hubble/plutos_moons.html
Reuse: This item is in the public domain and maybe reused freely without restriction.

Directions:

1. Ask the students to argue in the affirmative or negative for the retention of Pluto's classification as a planet. Have them utilize facts of Pluto and the IAU Planet Classification system (http://www.iau.org/public/pluto/).
2. Have the students write a 1 page, 12pt font double-spaced, summary of their position regarding Pluto's classification as a planet.

Pluto Facts:

1. Pluto is the smallest planet in the Solar System, smaller than Earth's Moon, and half the width of Jupiter's moon, Ganymede.
2. Pluto's journey around the Sun takes 248 Earth years. This means that, since its discovery in 1930, it still has 177 years to go until it has made a complete orbit around the Sun.
3. Pluto's atmosphere is composed of a thin layer of gas containing carbon monoxide, methane, and nitrogen. Its atmospheric pressure has been estimated to be 1/700,000 compared with that of earth.
4. Pluto orbits the Sun on a different plane than the other 8 planets, going over them and below them.
5. Pluto has three identified moons, Charon, the largest is not much bigger than Pluto itself. (Pluto is 2,280 kilometers wide, Charon is 1,212 kilometers wide).
6. A day on Pluto is equivalent to Earth's 6 days and 9 hours, meaning that it has the second slowest rotation in the Solar System (after Venus, which takes 243 days to turn on its axis).
7. Pluto's orbit is elliptical, meaning that it can come closer to the Sun than Neptune, but then go almost two billion kilometers further away from Neptune's orbit.
8. Pluto maximum distance from the Sun – 7.38 billion km (4.6 billion miles).
9. Pluto's minimum distance from Earth – 4.28 billion km (2.7 billion miles).

IAU Classification System:

1. A planet is a celestial body that

a. is in orbit around the Sun,

b. has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and

c. has cleared the neighborhood around its orbit.

1. A "dwarf planet" is a celestial body that

a. is in orbit around the Sun,

b. has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape,

c. has not cleared the neighborhood around its orbit, and

d. is not a satellite