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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Directions:
- 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/).
- Have the students write a 1 page, 12pt font double-spaced, summary of their position regarding Pluto's classification as a planet.
Pluto Facts:
- Pluto is the smallest planet in the Solar System, smaller than Earth's Moon, and half the width of Jupiter's moon, Ganymede.
- 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.
- 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.
- Pluto orbits the Sun on a different plane than the other 8 planets, going over them and below them.
- 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).
- 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).
- 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.
- Pluto maximum distance from the Sun – 7.38 billion km (4.6 billion miles).
- Pluto's minimum distance from Earth – 4.28 billion km (2.7 billion miles).
IAU Classification System:
- 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.
- 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