Transcript The Solar System

The Solar System
Essential Questions
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What is the difference between a planet
and a dwarf planet?
What is the difference between a meteor
and a meteorite?
What is the difference between an
asteroid and a comet?
How do we determine how far apart the
planets are?
How do the solar system bodies orbit the
sun?
What is the difference between a
planet and a dwarf planet?
IAU definition of Planet
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Former definition
• A non-luminous celestial body larger than an
asteroid or comet, illuminated by light from a
star, such as the sun, around which it revolves.
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 neighbourhood around its orbit.
IAU definition of a Dwarf Planet
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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)
shape2,
• (c) has not cleared the neighbourhood around
its orbit, and
• (d) is not a satellite.
Types of Planets
Terrestrial Planets
 Jovian Planets
 Dwarf Planets
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Terrestrial Planets
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Smaller size and mass
Higher density
Made mostly of rock and metal
Solid surface
Few, if any, moons
No rings
Closer to the Sun and each other
Warmer surfaces
Mercury, Venus, Earth, Mars
Video
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“A Spin Around the Solar System:
Our Rocky Neighbors: The Inner
Planets”
Mercury
Diameter = 4872 km
 Distance to the Sun =57.9 million
km
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Mars
Diameter =6 780 km
 Distance to the Sun =227.9 million
km
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Venus
Diameter =12 104km
 Distance to the Sun = 108.2 million
km
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Earth
Diameter =12 756 km
 Distance to the Sun =149.6 million
km
 Orbit period = 356.26 days
 Orbit speed = 108 000 km/s
 Axis rotation = 23.93 hours
 Axis tilt = 23.5o
 Acceleration = 9.81 m/s2
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Jovian Planets
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Larger size and mass
Lower density
Mostly made of hydrogen, helium, and
hydrogen compounds
No solid surface
Many moons
Rings
Farther from the sun and each other
Cool temperatures at cloud tops
Jupiter, Saturn, Uranus, Neptune
Video
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“A Spin Around the Solar System:
The Outer Planets the Gas Giants”
Jupiter
Diameter =142 984 km
 Distance to the Sun =778.4 million
km
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Saturn
Diameter =120 536 km
 Distance to the Sun =1.4 billion km
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Uranus
Diameter =51 118 km
 Distance to the Sun =2.4 billion km
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Neptune
Diameter =49 532 km
 Distance to the Sun = 4.5 billion km
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Dwarf Planets
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Pluto, Ceres, Eris
Video
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“A Spin Around the Solar System:
The Small Pieces: Asteroids, Comets,
and Pluto”
Ceres
Diameter = 974.6km
 Distance to the Sun =
413 832 587.5 km
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Pluto
Diameter =2 306km
 Distance to the Sun =
5 906 376 272km
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Eris
Diameter =2 600km
 Distance to the Sun = 67.665AU
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What is the Difference Between a
Meteor and a Meteorite?
meteoroid is a sand- to bouldersized particle of debris in the Solar
System
 meteor is the visible path of a
meteoroid that enters Earth's (or
another body's) atmosphere
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What is the difference between an
asteroid and a comet?
What is an Asteroid?
IAU Definition
(a) orbits the Sun inside the orbit of
Jupiter
 (b) does not have sufficient mass for
its self-gravity to overcome rigid
body forces so that it assumes a
hydrostatic equilibrium shape (it is
not round shaped),
 (c) has not cleared the
neighbourhood around its orbit, and
 (d) is not a satellite.
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Asteroids
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Small bodies
Believed to be left over from the beginning of
the solar system billions of years ago
100,000 asteroids lie in belt between Mars
and Jupiter
Largest asteroids have been given names
made of rocky and metallic minerals
random shapes
appear more clear than comets
when viewed through a telescope
Where are the asteroids?
Most asteroids are
located in two
regions:
•Asteroid belt
•Orbit of Jupiter… the
Hildas (the orange
"triangle" just inside
the orbit of Jupiter)
and the Jovian Trojans
(green). The group
that leads Jupiter are
called the "Greeks"
and the trailing group
are called the
"Trojans"
Asteroid Belt
Discovered in 1801
 Previously
predicted by Franz
Xaver Von Zach
 1801- Piazza found
Ceres
 Olbers found Pallas
and Vesta
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Asteroid Belt
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The region of space between Mars and Jupiter;
about 2.8AU
Hundreds of thousands of asteroids known.
Probably millions more!
3 types of asteroid: Carbonaceous, Silicate,
Metallic
Even the largest object in the belt, Ceres (dwarf
planet), is too dim to see without aid
Remnants of a planet-formation process that
failed due to Jupiter’s gravitational pull OR a
planet that was broken apart during a collision
What are Comets?
Comets
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Small icy bodies
Travel past the Sun
Give off gas and dust as they pass by
made of chemical compounds that
vaporize when heated
more elliptical (egg) shaped
appear fuzzier than asteroids when
viewed through a telescope
grow tails as they get closer to the Sun
highly elliptical orbits
Anatomy of a Comet
Anatomy of a Comet
Parts of a Comet
Nucleus= main mass of
ice/frozen gas
 Coma = cloud of gas surrounding
nucleus
 Tail = forms when ice vaporizes
as comet approaches Sun
 Hydrogen cloud = cloud of gas
that surrounds coma (only some
comets have these)
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http://science.nationalgeographic.com/science/space/solar-system/asteroids-comets-article.html
Where are the comets?
Kuiper Belt
A large body of small
objects orbiting (the short
period comets <200 years)
the Sun in a radial zone
extending outward from the
orbit of Neptune (30 AU) to
about 100 AU. Pluto maybe
the biggest of the Kuiper
Belt object.
Oort Cloud
Long Period Comets
(period > 200 years) seems
to come mostly from a
spherical region at about
50,000 AU from the Sun.
Kuiper Belt
Discovered in 1992
 Named for Dutch Astronomer Gerard
Kuiper, who had PREDICTED its
existence in 1951.
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Kuiper Belt
Region beyond Neptune; 30 to over
50AU
 At least 70,000 small, icy, slowmoving, objects
 Very faint objects because small, far
and reflect light from Sun
 A million times fainter than faintest
we can see with naked-eye
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Oort Cloud
Hypothetical spherical cloud. No
direct observations.
 Proposed by Ernst Opik (1932), Jan
Henrik Oort (1950)
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Oort Cloud
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50,000AU; defines gravitational boundary
of solar system
Source of long-period comets (comets that
have an orbit of hundreds or thousands of
years)
Objects composed of ices (water,
methane, and ammonia)
2 regions:
• outer sphere
• inner disc
What are the Types of Comets?
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Short-period comets
• periods of less than 200 years,
• are returning as predicted on wellknown orbits
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Long-period comets
• periods of more than 200 years
• among the brightest have been several
How do we determine how far apart
the planets are?
Bode’s Law
•A rough rule that predicts the spacing of the planets in the Solar System
•To find the mean distances of the planets, beginning with the following simple sequence of
numbers:
0 3 6 12 24 48 96 192 384
•With the exception of the first two, the others are simple twice the value of the preceding
number.
•Add 4 to each number:
4 7 10 16 28 52 100 196 388
•Then divide by 10:
0.4 0.7 1.0 1.6 2.8 5.2 10.0 19.6 38.8
Planet
Actual Distance (AU)
Bode’s Law
Mercury
0.39
0.4
Venus
0.72
0.7
Earth
1.00
1.0
Mars
1.52
1.6
Jupiter
5.20
5.2
Saturn
9.54
10.0
Uranus
19.2
19.6
Neptune
30.1
38.8
Works
for
moons
too!
How do the solar system bodies
orbit the sun?