1. Dwarf Planets, Comets, Asteroids, and Kuiper Belt Objects

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3. Who predicted the existence of an additional planet in 1905?
Halley
Tombaugh
Oort
Lowell 1
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4. Lesson Overview Pluto Asteroids Comets The Oort Cloud and Kuiper Belt
Chapter 3, Lesson 4

5. Vocabulary Questions Slide Index
Click any link below to go directly to polling that question.
Mean between Earth and Sun
Theoretical sphere, containing billions of comet nuclei
Region between Mars and Jupiter
Disk-shaped region beyond Neptune’s orbit
Solid core of a comet
Dust part of comet's head
Streak of light in the sky when a rock particle falls to Earth
Gas swept away from comets head
Extremely bright meteor
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6. The Discovery of Pluto
Percival Lowell predicted the existence of an additional planet in 1905
Clyde Tombaugh used a device called a blink comparator to look for planetary motion
Chapter 3, Lesson 4
Courtesy of New Mexico State University, Las Cruces, NM

7. The Discovery of Pluto
On 18 February, 1930, Tombaugh spotted the “jump” of a tiny dot on a photograph
Chapter 3, Lesson 4
Courtesy of Lowell Observatory

8. Pluto’s Orbit and Atmosphere
Pluto’s orbit is eccentric
Averages 40 astronomical units from the Sun, but it ranges from 30 units to 50 units
An astronomical unit, or AU, is the mean distance between the Earth and the Sun, about 93 million miles
Chapter 3, Lesson 4

9. Pluto’s Orbit and Atmosphere
Pluto has an atmosphere, but not year-round
At perihelion it “warms up”
At aphelion it receives so little solar energy that its surface is below the temperature at which methane freezes
Courtesy of NASA, ESA, H. Weaver (JHUAPL), A. Stern (SwRI), and the HST Pluto Companion Search Team
Chapter 3, Lesson 4

10. The Synchronous Orbit of Pluto’s Moons
Charon & Pluto are locked in a synchronous orbit
The two bodies circle around their common center of mass once every 6.4 days
Chapter 3, Lesson 4

11. Asteroids
The asteroid belt – the region between Mars and Jupiter where most asteroids orbit
Jupiter’s gravitational pull has created gaps in the asteroid belt at 2.50 AU and 3.28 AU
Chapter 3, Lesson 4

12. The Origins of Asteroids
Astronomers once thought that asteroids were the remains of a planet that had exploded
Explanation that seems more plausible today: asteroids are simply primordial material that never formed into a planet
Jupiter’s gravity keeps pulling
on objects in the asteroid belt
and stirring them up
Chapter 3, Lesson 4
Courtesy of Galileo Project/NASA/JPL

13. Comets’ Predictable Orbits Around the Sun
In 1705 Halley boldly predicted the comet’s return in 1758
On Christmas night of 1758, Comet Halley appeared in the sky
Scientists have traced Halley sightings back to 239 BC
Video
Chapter 3, Lesson 4
© Datacraft/age fotostock

14. A Comet’s Three Main Parts
A comet consists of a head and a tail
Head is made up of a nucleus—the solid core of a comet—and a coma
A coma is the part of a comet’s head made up of diffuse gas and dust
The tail of a comet is the gas and/or dust swept away from the comet’s head
Chapter 3, Lesson 4

15. A Comet’s Three Main Parts, cont.
Chapter 3, Lesson 4

16. Comet Hale-Bopp
Dust tail – white - consists of dust particles pushed out of the coma by the radiation from the Sun
Heaven’s Gate
Ion Tail – Blue - Solar wind that sweeps past the comet has a very high speed (about 500 km/s) and causes the tail to be always orientated exactly in the anti-solar direction
3/26/97

17. The Shell of Comets Surrounding the Solar System
In 1950 Oort revived an idea that in a space far beyond Neptune’s orbit, a great number of comets orbit the Earth
Oort cloud - a theoretical sphere, between 10,000 AU and 100,000 AU from the Sun, containing billions of comet nuclei
Chapter 3, Lesson 4

18. The Small Band of Comets That Make Up the Kuiper Belt
In 1951 Kuiper proposed a second, smaller band of comets within the Oort cloud
The Kuiper belt is a disk-shaped region beyond Neptune’s orbit, 30 AU to 1,000 AU from the Sun and the presumed source of short-period comets
Chapter 3, Lesson 4

19. Meteors vs. Meteorites
Meteor – a streak of light in the sky caused when a rock particle falling to Earth is so heated by friction with the atmosphere that it emits light
Fireball – an extremely bright meteor
Object that causes the meteor is a meteoroid
Meteorite is an interplanetary chunk of matter
that has struck a planet or a moon
Meteor hits Russia clip
Chapter 3, Lesson 4

20. The asteroid belt is between what two planets?
Mercury and Venus
Venus and Earth
Earth and Mars
Mars and Jupiter 1
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21. Which of these is not part of a comet?
Coma
Nucleus
Proton
Tail 1
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22. Review Pluto was downgraded to a dwarf planet in 2006
Astronomers don’t bother naming asteroids until they have calculated their orbits so most asteroids go nameless
Comets usually have two tails, although one or both may be very small
Scientists calculate that over the entire Earth, there must be some 25 million meteors every day that are visible to the naked eye
Chapter 3, Lesson 4

23. Summary Pluto The Asteroids Comets The Oort Cloud and Kuiper Belt
Chapter 3, Lesson 4

24. Next… Done – Dwarf Planets, Comets, Asteroids, and Kuiper Belt Objects
Next – The Milky Way Galaxies
Chapter 3, Lesson 4
Courtesy of NASA/JPL-Caltech

25. The mean distance between the Earth and Sun, about 93 million miles (150 million km). (p. 134)
Aphelia
Astronomical unit
Solar unit
Planetary unit 1
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26. The region between Mars and Jupiter where most asteroids orbit. (p
Oort cloud
Asteroid belt
Kuiper belt
Kepler belt 1
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27. The solid core of a comet. (p. 139)
Nucleus
Coma
Tail
Corona 1
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28. The part of a comets head made up of diffuse gas and dust. (p. 139)
Nucleus
Tail
Corona
Coma 1
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29. The gas and/or dust swept away from the comets head. (p. 139)
Comet nuclei
Meteorite materials
Tail of a comet
Frozen carbon dioxide 1
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30. A theoretical sphere, between 10,000 AU and 100,000 AU from the Sun, containing billions of comet nuclei. (p. 141)
Oort cloud
Kuiper belt
Asteroid belt
Kepler belt 1
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31. A disk-shaped region beyond Neptune’s orbit, 30 AU to 1,000 AU from the Sun and the presumed source of short-period comets. ( p. 143)
Oort cloud
Asteroid belt
Kepler belt
Kuiper belt 1
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32. A streak of light in the sky caused when a rock particle falling to Earth is so heated by friction with the atmosphere that it emits light. (p. 143)
Meteorite
Fireball
Meteor
Meteoroid 1
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33. An extremely bright meteor. (p. 143)
Meteorite
Fireball
Meteor
Meteoroid 1
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