Download Night Sky III Planetary Motion Lunar Phases Astronomy 1 — Elementary Astronomy

Night Sky III
Planetary Motion
Lunar Phases
Astronomy 1 — Elementary Astronomy
LA Mission College
Spring F2015
Quotes & Cartoon of the Day
“Everything has a natural
explanation. The moon is not
a god, but a great rock, and
the sun a hot rock. “
-- Anaxagoras (500 BC – 428
BC)
“Nature gives to every time
and season some beauties of
its own; and from morning to
night, as from the cradle to the
grave, it is but a succession of
changes so gentle and easy
that we can scarcely mark
their progress.“
-- Charles Dickens
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Announcements
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First HW, through part of today’s material, posted
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due Tuesday 9/22
First midterm currently planned 9/24
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may move out one week
will confirm Tuesday
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Last Class
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Annual Motion
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Zodiac
Seasons
Planetary Motion
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
This Class
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Seasons Questions revisited
Planetary Motion
Lunar Phases
LT: Predicting Lunar Phases
Eclipses (time permitting)
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Seasons Review
Astronomy 1 — Elementary Astronomy
LA Mission College
Spring F2015
Seasons Review
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Axial Tilt
Energy transfer
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Let’s Practice
Which lettered position (A-E), in the image below, best
represents the location on Earth that is experiencing
summer in the Southern Hemisphere?
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
If Earth were tilted more (60° rather than 23.5°), then
during winter at your location you would _____
compared to what you experience during winter now.
A. experience cooler temperatures
B. experience warmer temperatures
C. not experience any significant change in
temperature
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Planets... the Wanderers
Astronomy 1 — Elementary Astronomy
LA Mission College
Spring F2015
Planets... the wanderers
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It was a warm summer evening in ancient Greece....
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Apparent Motion of Planets
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Indeed originally named for their “wandering” movement
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Most of the time rise a bit later each night
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“Late Old English planete, from Old French planete (Modern
French planète), from Late Latin planeta, from Greek
planetes, from (asteres) planetai "wandering (stars),..."
move eastward against the background stars
Sometimes appear to go “backwards” for a while
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i.e. rise earlier each night/go westward
This is called apparent retrograde motion
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Mars and Retrograde Motion
QuickTime movie from Dr. Ted Snow's web site at The University of Colorado, Boulder.)
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
WHY DO WE SEE APPARENT
RETROGRADE MOTION?
The Motion of the Planets
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orbit in almost the same plane
relative positions change with time
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Apparent Retrograde Motion
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Planets orbit the Sun at differing rates.
sometimes Earth will “catch up to and pass” another
planet
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planet appears to pause in its eastward progression and
“move backwards”
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never actually change orbit!
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Retrograde Motion
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http://www.bisque.com/help/Patterns/image/retrograde_motion_of_mars_wmf.gif
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Frequency and Length Vary
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Synodic period — how often
Example Mars
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3/1/2014 to 5/19 2014
4/17/2016 to 6/29/2016
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Let’s Practice
For how many days was this planet in retrograde
motion?
May
A. 10 days
B. 12 days
C. 15 days
D. 17 days
E. 32 days
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
On which date would the planet appear to rise in the
west?
May
A. March 1
B. March 31
C. April 5
D. April 12
E. Never Ever, Never, Ever, EVER!!!!!!!
Never,
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Lunar Cycles & Phases
Astronomy 1 — Elementary Astronomy
LA Mission College
Spring F2015
PHASES OF THE MOON
Moon’s Orbit
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The Moon orbits the Earth every 27.3 days (sidereal
month)
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sidereal means relative to the stars
Full moon to full moon is every 29.5 days (synodic month)
This is a right-handed revolution, like the Earth
The Moon is tidally locked to the Earth
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It also rotates once every 27.3 days
Same side always faces Earth
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Lunar Phases
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We see different phases of the Moon depending on
where the Moon is in it’s orbit around the Earth, with
respect to the Sun.
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Half the Moon is lit at all times by the Sun.
We view the half dark/half lit Moon from different angles,
which creates the different appearances at different phases
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Moon Phase Animation
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We see different phases of the Moon depending on
where the Moon is in it’s orbit around the Earth, with
respect to the Sun.
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Half the Moon is lit at all times by the Sun.
We view the half dark/half lit Moon from different angles,
which creates the different appearances at different phases
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Lunar Phase Diagram
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Waxing — getting
bigger
(approaching Full)
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Waning — getting
smaller
(approaching
New)
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Let’s Practice
The diagram below shows Earth and the Sun as well as
five different possible positions for the Moon. Which
position (B-D) of the Moon best corresponds with the
Moon phase shown in the upper right corner?
X
X
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
The diagram below shows Earth and the Sun as well as
five different possible positions for the Moon. Which
position (A-E) of the Moon best corresponds with the
Moon phase shown in the upper right corner?
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Which of these positions would be the waning crescent
moon?
A. 2
B. 4
C. 6
D. 8
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Is there really a “dark side of the Moon” that never
receives sunlight?
A. yes
B. no
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
TIMING OF LUNAR PHASES
Lunar Phases & Timing
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Different phases rise, set & transit @ different times
of day
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transit — reaches the highest point/between rising & setting
How do we tell what time it is?
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Or, how did we before watches, iPhones & atomic clocks?
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Lunar Phase Timing
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Sun
overhead —
noon
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new moon
is transiting
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3rd Quarter
is setting
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1st Quarter
is rising
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Lunar Phase Timing
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Sun is
setting — 6
PM
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1st Quarter
is transiting
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New Moon
is setting
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Full moon
is rising
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
LT Predicting Moon Phases
(If time)
Astronomy 1 — Elementary Astronomy
LA Mission College
Spring F2015
Which phase of the Moon rises at 9 AM?
A. waning gibbous
B. third quarter
C. first quarter
D. waxing crescent
E. none of the above
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
LT PREDICTING MOON PHASES
Which phase of the Moon rises at 9 AM?
A. waning gibbous
B. third quarter
C. first quarter
D. waxing crescent
E. none of the above
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Let’s Practice
At what local apparent solar time does the full moon
transit?
A. noon
B. 6 PM
C. 9 PM
D. midnight
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
At midnight, local apparent solar time, what phase will
be rising?
A. Waning Gibbous
B. First Quarter
C. Third Quarter
D. New
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
If you see a crescent moon very high in the sky in the
fairly early morning morning, is it waxing or waning?
A. waxing
B. waning
C. it depends on the day of the month
D. this is not possible
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
You observe a full moon rising around 7 P.M. In what
phase will you observe the moon setting the next
morning?
A. New Moon
B. Waning Gibbous
C. Full Moon
D. Third Quarter
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
ECLIPSES
Eclipses
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Lunar eclipse — Earth precisely between Moon and Sun
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Earth’s shadow falls on Moon
Moon goes dark (reddish actually)
Solar eclipse — Moon precisely between Sun and Earth
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Moon’s shadow falls on Earth
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partly in some places (partial solar eclipse)
Sunlight blocked completely in some places (total solar
eclipse)
and not at all in most places
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Apparent Size of Sun and Moon
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The Sun and Moon appear to have the same size
when viewed from Earth.
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Makes total solar eclipse possible
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Eclipses
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So... once a month the
Moon is between the
Earth and the Sun....
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New Moon…
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Why don’t we have a
solar eclipse every
month?
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Or a lunar eclipse every
month?
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
The Moon’s Orbit is tilted
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The Moon’s orbit tilted relative to the Earth’s orbit
around the sun by about 5°
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(recall its apparent angular size is ~ 0.5°)
Most of the time, the moon is above or below the
direct line from Sun to Earth.
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
The Moon’s Orbit is tilted
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Periodically, the Moon crosses the line from Earth to
Sun.
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If it does so at full moon, we have a Lunar Eclipse
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The Earth’s shadow falls on the Moon
If it does so at new moon, we have a Solar Eclipse
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The Moon’s shadow Falls on the earth
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Lunar Eclipse
Path for penumbral
eclipse
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Lunar Eclipse
Progression of Total Lunar
Eclipse
<----------
Partial Lunar Eclipse
---------->
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Lunar Eclipses 2010-2017
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Solar Eclipses
Image: Sanhujinka.com
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Solar Eclipse
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
A Total Solar Eclipse
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Solar Eclipses
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Next good US TOTAL solar eclipse opportunity is in
2017
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Let’s Practice
Suppose it is early in the month and you are going on a
cruise to view a total solar eclipse later the same
month. The moon is currently full. If it only takes a day
or so to get to the viewing location, about when might
your cruise depart?
A. tomorrow
B. next week
C. about two weeks from today
D. at the very end of the month
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
If you found yourself on a planet very similar to Earth
with a moon very similar to our Moon, what would you
conclude if you observed a total lunar eclipse every full
moon?
A. That this planet’s moon orbits in the same plane as
the planet orbits its star.
B. That this planet’s moon is much larger than our Moon.
C. That this planet’s star is much more distant than our
Sun.
D. That this planet’s moon orbits over the poles of the
planet rather than near its equator.
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
WRAP-UP
Topic for Next Class
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History part I
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Greeks to Kepler
Kepler & Brahe
Kepler’s Laws
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Reading Assignment
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Ch 3 in either text
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Homework
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Sci, Annual, Diurnal due 9/22
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015