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Our Solar System
Introduction and Key Terms
Learning Outcomes (Students will…)
-Explain the theories for the origin of the solar system
-Distinguish between questions that can be answered by science and those
that cannot, and between problems that can be solved by technology and
those that cannot with regards to solar system formation.
-Estimate quantities of distances in parsec. Estimate the age of the solar
system.
-Describe and apply classification systems and nomenclature used in the
sciences. Classify planets as terrestrial vs. Jovian, inner vs. outer, etc.
Classify satellites. Classify meteoroid, asteroid, dwarf planet, planet.
Classify comets as long period vs. short period. etc
-Formulate operational definitions of major variables. Given data such as
diameter and density describe the properties that divide the planets and
moons into groups.
-Tools and methods used to observe and measure the inner and the outer
planets and the minor members of the solar system
Planetary Systems
• A planetary system consists of the
various non-stellar objects orbiting a star
such as planets, dwarf planets, moons,
asteroids, meteoroids, comets, and cosmic
dust.
Solar System
• A specific planetary system around our star
• The region of space that falls within the gravitational
influence of our Sun
• If you consider the edge of the Solar System to be
Pluto’s orbit, the Solar System has a diameter of
79 AU
• Consists of:
–
–
–
–
–
–
an ordinary yellow star – the Sun
Eight Planets
Their moons
Dwarf planets
Asteroids, Comets, Meteors and Meteorites
Cosmic dust
Star
• A star is a massive, luminous ball of
plasma that is held together by gravity.
• Our star is the Sun
• The gravity on the Sun is 274 m/s2
Planets
• There are now 8 planets in our Solar
System
• The Sun is one of the foci for each of
these planets
What is a Planet?
• Former definition: NASA (2000):
– Planet: 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.
– What is wrong with this definition?
– Why did the definition change?
New definition: NASA (2006):
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.
Classifying Planets
• Planets can be classified by:
– 1)
– 2)
– 3)
– 4)
– 5)
Composition
Size
Proximity to the Sun
Position relative to Earth
History
1) Composition
A) Rocky or Terrestrial
planets (4)
B) Jovian planets (4)
Terrestrial Planets
- Composed primarily of rock
and metal
- No rings
- Few satellites (moons)
- High density
- Slow rotation
- Solid surface
Jovian Planets
- Composed primarily of gas
(hydrogen and helium)
- Rings
- Many satellites (moons)
- Low density
- Rapid rotation
- Deep atmospheres
2) Size
A) Small planets (4)
B) Giant planets (4)
Small Planets
- Diameters less than
13,000 km
Giant Planets
- Diameters greater than
48,000 km
- Also called gas giants
3) Proximity to Sun
A) Inner planets (4)
B) Outer planets (4)
The asteroid belt between Mars
and Jupiter forms the
boundary between the inner
solar system and the outer
solar system.
4) Position relative to
Earth
A) Inferior planets (2)
B) Earth
C) Superior planets (5)
Inferior Planets
-
-
Closer to the Sun than
Earth
Show phases like the
Moon’s when viewed from
Earth
Superior Planets
-
-
Farther from the Sun than
Earth
Always appear full or nearly
full
5) History
A) Classical planets
B) Modern planets
C) Earth
Classical Planets
•
•
•
Known since prehistoric
times
Visible to the unaided eye
(no telescope needed)
In ancient times this term
also referred to the Sun
and the Moon
Modern Planets
•
•
Discovered in modern
times
Visible only with optical aid
or telescope
What is a Dwarf Planet?
• NASA (2006):
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 neighbourhood around its
orbit, and
(d) is not a satellite.
SHAPE…
Ceres (dwarf planet)
Photo: Hubble Space
Telescope
Dwarf Planets
• Pluto (direct observation)
• Ceres (direct observation)
– Discovered in 1801!!!
– Classified as a planet for 50 years
– Demoted to asteroid
– Promoted to dwarf planet
• Eris (larger than Pluto)
– Discovered in 2005
– Controversial decision regarding Pluto…
Dwarf Planets
• Makemake and Haumea are determined
to be dwarf planets using mathematical
calculations…
Other Celestial Bodies in Our Solar
System
• All objects besides planets and dwarf
planets, except satellites, orbiting the Sun
shall be referred to collectively as “Small
Solar-System Bodies”.
• Some “small Solar-System bodies”
include:
– Asteroids
– Comets
Asteroids
– An asteroid (or minor planet)
• (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 neighborhood
around its orbit, and
• (d) is not a satellite.
SHAPE…
Vesta (asteroid
or minor planet)
Clearing the Neighborhood
• There are very few other objects in the
vicinity of Jupiter and the inner planets that
orbit the Sun.
• Vesta and Ceres have many other
asteroids in relatively nearby orbits.
Key Terms
• 1) Draw a diagram for each with labels to
show the difference between a planet,
dwarf planet and asteroid.
• 2) Create a metaphor or analogy for
comparison.
3) Create a Venn Diagram for
these three terms.
1) Decide…Planet, Dwarf Planet
or Asteroid?
2) Decide…Planet, Dwarf Planet
or Asteroid?
3) Decide…Planet, Dwarf Planet
or Asteroid?
4) Decide…Planet, Dwarf Planet
or Asteroid?
5) Decide…Planet, Dwarf Planet
or Asteroid?
6) Decide…Planet, Dwarf Planet
or Asteroid?
7) Decide…Planet, Dwarf Planet
or Asteroid?
8) Decide…Planet, Dwarf Planet
or Asteroid?
New English Words…
• Plutoed…
• Ceresed…