Transcript Dwarf Planets, Comets, Asteroids, and Kuiper Belt Objects

Dwarf Planets, Comets, Asteroids,
and Kuiper Belt Objects
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Halley
Tombaugh
Oort
Lowell
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Lesson Overview
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Pluto
Asteroids
Comets
The Oort Cloud and Kuiper Belt
Chapter 3, Lesson 4
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Mean between Earth and Sun 6.
Theoretical sphere, containing
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Region between Mars and
billions of comet nuclei
Jupiter
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Solid core of a comet
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Dust part of comet's head
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Gas swept away from comets
head
Disk-shaped region beyond
Neptune’s orbit
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Streak of light in the sky when a
rock particle falls to Earth
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Extremely bright meteor
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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
Chapter 3, Lesson 4
Courtesy of NASA, ESA, H. Weaver
(JHUAPL), A. Stern (SwRI), and the HST
Pluto Companion Search Team
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
Chapter 3, Lesson 4
Video
© Datacraft/age fotostock
A Comet’s Three Main Parts
A comet consists of a head and a tail
1. Head is made up of a nucleus—the solid
core of a comet—and a coma
2. A coma is the part of a comet’s head
made up of diffuse gas and dust
3. 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
Chapter 3, Lesson 4
Meteor hits Russia clip
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Mercury and Venus
Venus and Earth
Earth and Mars
Mars and Jupiter
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Coma
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Proton
Tail
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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
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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
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Aphelia
Astronomical unit
Solar unit
Planetary unit
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Oort cloud
Asteroid belt
Kuiper belt
Kepler belt
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Nucleus
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Nucleus
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Comet nuclei
Meteorite materials
Tail of a comet
Frozen carbon dioxide
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Oort cloud
Kuiper belt
Asteroid belt
Kepler belt
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Oort cloud
Asteroid belt
Kepler belt
Kuiper belt
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Meteorite
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Meteorite
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