Download Lesson 1 PPT - McCreary County Schools

Warm Up Questions
1. Which planet is bigger, Mercury or Jupiter ?
2. Are the gas giant planets closer to the Sun
than the rocky planets (yes/no)?
3. How many planets are in the Solar System?
4. Is the Sun bigger, smaller, or the same size
as the Moon?
5. What is the difference between the Solar
System and the Milky Way Galaxy (just one
sentence) ?
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Solar System = Sun, 8-planets (their 166 known moons), dwarf
planets (to be defined next class), and small Solar System bodies
(e.g., comets and asteroids). All of these celestial objects are
bound to the Sun by gravity and formed 4.6 billion years ago.
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Why are there only 8 planets now?
Three types of objects orbit our Sun:
1. Planets
2. Dwarf Planets
• Plutoids
3. Small solar system bodies
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What is a planet?
• In August of 2007 the International Astronomical
Union redefined what a planet is (no official scientific
definition of a "planet" existed before). A planet:
1. Is a body that orbits the Sun (this definition only
applies to our Solar System)
2. Is large enough for its own gravity to make it round
3. And has "cleared its neighborhood" of smaller objects
• So a new the category of dwarf planet was created,
which currently includes Pluto, Eris*, Haumea,
Makemake and and Ceres**.
*Eris is the largest known dwarf planet in the Solar System and the ninth largest
body known to orbit the Sun. Its distance from the Sun is 97 AU.
**Ceres is the smallest identified dwarf planet in the Solar System and, because
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it’s the largest asteroid, the only dwarf planet in the asteroid belt.
What is meant by “cleared its
neighborhood of smaller objects”?
Pluto’s orbit is very elliptical (29-49 AU). When Pluto is outside the orbit of Neptune
(30 AU) it enters the Kuiper belt, which is comprise of icy objects some of which are
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smaller and some actually bigger than Pluto.
What is a Dwarf Planet?
• Celestial body orbiting the Sun
• Massive enough to be rounded by its
own gravity
• BUT has NOT cleared its neighboring
region of planetesimals
• Is not a satellite
A plutoid is a dwarf planet beyond the orbit
of Neptune
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Only 5 Dwarf Planets recognized so far
but there may be more than 200
Pluto, approximate
true color
Makemake,
(Artist’s conception)
Ceres, seen through
Eris, seen through
(Hubble telescope)
(Hubble telescope)
Haumea, with its 2 moons,
Hi‘iaka and Namaka
(Artist’s conception)
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Pacific Island Names for Dwarf Planets
• Haumea is the
Hawaiian goddess
of childbirth and
fertility.
• The the moons
"Hiʻiaka" and
"Namaka” are
named after after
two of Haumea's
daughters.
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Pacific Island Names for Dwarf Planets
• Makemake is the
creator of humanity
in the mythos of the
Rapanui, the native
people of Easter
Island. The name
choice preserves
the planetary
object's connection
with Easter Island.
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What are Small Solar System Bodies?
• Neither a planet nor a dwarf planet
• All other objects orbiting the Sun
• All minor planets except dwarf planets
• Asteroids (except Ceres, the largest
asteroid)
• Comets
• The bodies are not massive enough to
be rounded by their own gravity
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Characteristics of Terrestrial and
Gas Giant Planets
Terrestrial Planets
•
Mercury, Venus,
Earth, Mars
1. Rocky
 More dense
2. Smaller
3. More closely spaced
4. Closer to the Sun
Gas Giant (Jovian) Planets
• Jupiter, Saturn,
Uranus, Neptune
1. Gaseous, made of
hydrogen and helium
 Less dense (Saturn
would float)
2. Larger
3. Spaced farther apart
4. Farther from the Sun
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Terrestrial Planets
Venus
Mercury
Moon
Mars
12
Uranus
Gas
Giants
Earth to scale
Jupiter
Neptune
Saturn
Surface Temperature on Planetary Objects
1000
Surface Temperature in Fahrenheit
800
600
400
200
0
-200
-400
-600
0
1
2
3
4
5
6
7
8
9
10
Planet Order
Do you see patterns or anomalies in the data?
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Length of day on planetary objects
200
2
1
100
50
0
Mercury
Venus
Earth
Moon
Mars
Jupiter
-50
-100
Saturn
Uranus
Neptune
Pluto
Length of Day relative to Earth (days)
Length of Day relative to Earth (days)
150
0
Mercury
Venus
Earth
Moon
Mars
Jupiter
Saturn
Uranus
Neptune
-1
-2
-3
-4
-5
-6
-150
-7
Planet
Planet
Do you see patterns or anomalies in the data?
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Pluto
Planetary Density
Do you see patterns or anomalies in the data?
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The Milky Way Galaxy
100,000 light years across
1,000 light years thick
200 billion stars
You are here
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Extra Slides
Universe = All matter, all stars, all planets.
The Big Bang created the Universe 13.7 billion years ago.
Composition of the Universe at this time was mostly hydrogen
and some helium.
The Milky Way Galaxy
A galaxy, is a grouping of billions of stars. There are about 200-400 billion stars
in our galaxy, the Milky Way Galaxy.
The Milky Way is ~100,000 light year across and about 1,000 light years thick.
Milky way viewed edge on from Earth
The Andromeda Galaxy, also a spiral
galaxy, is the nearest spiral galaxy to our
own, the Milky Way, at approximately 2.5
million light-years away.
The Milky Way Galaxy
The Sun and the planets are part of
the Milky Way galaxy. Located in
one of the arms, our Solar System
revolves about the center of the
galaxy at a speed of over 200 km
per second. Yet the galaxy is so
vast that it takes about 250 million
years to complete one revolution!
The Sun has yet to complete its
nineteenth orbit about the galactic
center.
You are here
Is the Andromeda Galaxy within the Milky Way Galaxy?
A.
B.
C.
D.
E.
Yes, it definitely is!
I think it is but I’m not sure.
I don’t think it is but I’m not sure
No, it definitely is not!
I don’t know how to determine
whether it’s inside or outside our
galaxy
Planet Masses
Do you see patterns or anomalies in the data?
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Temperatures In the Solar System
• Mercury exhibits the largest
variation in temperature of any
body in the Solar System (-330
to 750oF*) because it has no
atmosphere.
• The Moon also has large but
less extreme temperature
variations (-230 to 240oF*) for
the same reason.
• Atmospheres are like blankets
that insulate a planet from
extreme temperature swings.
MESSENGER image of Mercury
*Temperature minimum and maximum are for
night time and day time temperatures.
Temperatures In the Solar System
•
•
Venus has the highest
temperature of any planet in
the Solar System at 864oF!
Hot enough to melt lead.
Yikes!
Its temperature does not vary
from day to night like Mercury,
Earth, the Moon and Mars
because its atmosphere is
1.
2.
Venus Express image of Venus
Thick and dense
Effective at trapping the
Sun’s heat
Temperatures In the Solar System
•
Earth’s average (57.5oF)
temperature is just right
–
–
Not too hot to evaporate
all its water away
Not too cold to freeze all
its water and keep it ice
Temperature extremes are
also minor relative to
Mercury and the Moon
(average min 40o and
max 75oF)
Earth’s atmosphere from the international Space Station
Temperatures In the Solar System
•
•
•
Mars' thin atmosphere, visible on the horizon
in this low orbit image
Mars’ average (-50oF), so any
water is frozen solid
Mars has a thin atmosphere (1%
that of Earth) so it does moderate
the temperature some.
Maximum temperature is close to
Earth’s average low (20oF) but
the low on Mars is very cold (120oF)
Do all planet in our Solar System orbit
the Sun in the same direction?
A.
B.
C.
D.
E.
Yes, they orbit in the same
direction
Maybe
I don’t think they do
No, they don’t orbit in the
same direction
I’ve never thought about that
before
Planetary Orbit Direction
• All planets orbit the Sun in the same
direction: counterclockwise.
Do all planets have the same length of year
(e.g. 365.25 Earth days)?
a) Yes
b) No
Orbital period
(Earth years)
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptun
e
Pluto
0.24
0.62
1
1.88
11.86
29.46
84.01
164.8
247.7
Where a year equals one trip around the Sun
Orbital Velocity
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Orbital velocity varies systematically
with distance from the Sun
Orbit Velocity (km/sec)
50
40
30
20
10
0
Mercury
Venus
Earth
Moon
Mars
Jupiter
Planet
Saturn
Uranus
Neptune
Pluto
Gravity and Radius of the Planets
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