Dwarf Planets, Comets, Asteroids, and Kuiper Belt Objects

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Who predicted the existence of an additional planet in 1905? Halley Tombaugh Oort Lowell 1 (AS300-U1C3L4:LQ2)

Lesson Overview Pluto Asteroids Comets The Oort Cloud and Kuiper Belt Chapter 3, Lesson 4

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 Click here to return to this index.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The asteroid belt is between what two planets? Mercury and Venus Venus and Earth Earth and Mars Mars and Jupiter 1 (AS300-U1C3L4:LQ3)

Which of these is not part of a comet? Coma Nucleus Proton Tail 1 (AS300-U1C3L4:LQ4)

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

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

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

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 (AS300-U1C3L4:VQ1)

The region between Mars and Jupiter where most asteroids orbit. (p Oort cloud Asteroid belt Kuiper belt Kepler belt 1 (AS300-U1C3L4:VQ2)

The solid core of a comet. (p. 139) Nucleus Coma Tail Corona 1 (AS300-U1C3L4:VQ3)

The part of a comets head made up of diffuse gas and dust. (p. 139) Nucleus Tail Corona Coma 1 (AS300-U1C3L4:VQ4)

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 (AS300-U1C3L4:VQ5)

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 (AS300-U1C3L4:VQ6)

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 (AS300-U1C3L4:VQ7)

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 (AS300-U1C3L4:VQ8)

An extremely bright meteor. (p. 143) Meteorite Fireball Meteor Meteoroid 1 (AS300-U1C3L4:VQ1)