Transcript 2 Periodic Events I - Journigan-wiki

PERIODIC EVENTS
Warm Up
1. Name the original crew of Apollo 13.
2. What was the mission objective for Apollo
13?
3. Why was Ken Mattingly scrubbed from
the mission?
4. Who replaced Ken Mattingly on Apollo
13?
Warm Up
1. Name and define Newton’s three laws of
planetary motion.
2. Name and define Newton’s law of
gravity.
Warm Up
1.
On Planet X, a 50 gram weight is suspended
from string that is 23 centimeters long. The
weight pendulums 58 times in 60 seconds.
What is the acceleration due to gravity on
Planet X?
2. On Planet O, a 100 gram weight is suspended
from string that is 50 centimeters long. The
weight pendulums 45 times in 60 seconds.
What is the acceleration due to gravity on
Planet O?
Warm Up
1.
2.
3.
4.
5.
What elements do you need to form an
ellipse?
What does ellipticity mean?
What causes day and night to occur?
What happens to the relationship
between the Sun and Earth for spring,
summer, winter and summer to occur?
What happens to the lengths of the days
and nights as the year progresses?
Day
Night
Season
Equinox
revolution
solstice
eclipse
umbra
precession
penumbra
moon phases
annular
partial
rotation total
Warm Up-09/23/13
1.
2.
3.
4.
5.
What causes the seasons?
What is a solstice?
When do they occur?
What is an equinox?
When do they occur?
Periodic Events: Index
Seasons
Precession
Lunar Cycles
Solar Eclipses
Lunar Eclipses
Day and Night
Because of the clock-like order of our Universe,
certain astronomical phenomenon repeat themselves.
Day and Night
• Day and night are caused by the Earth’s
rotation of its axis.
• Days are longer in the summer and
shorter in the winter.
• http://www.cs.sbcc.cc.ca.us/~physics/flash
/LengthofDay.swf
Seasons
• Many people believe that the seasons are
caused by the Earth traveling closer to and
farther away from the Sun.
Seasons
At its closest (aphelion), the sun is 91.4 million
miles away from us. At its farthest
(perihelion), the sun is 94.5 million miles
away. That might sound like a lot, but it isn’t.
The Earth’s temperature barely changes from
it. The real reason for the seasons is…..
Seasons
…the tilt of the Earth on its axis!!!
As the Earth orbits the Sun, the orientation of
its axis remains fixed.
Warm Up
1. What events correspond to the following dates:
6/21, 9/21, 12/21 and 3/21.
2. Describe the lengths of the days on the above
dates.
3. During what season is the Sun the highest in
the sky?
4. During what season is the Sun the lowest in
the sky?
5. How does the Earth’s axial tilt determine the
seasons?
Seasons
During June, the northern hemisphere tilts toward the
Sun. The more direct sunlight heats the northern
hemisphere more than the southern hemisphere,
where it is Winter.
Length of Day
• http://www.cs.sbcc.cc.ca.us/~physics/flash
/LengthofDay.swf
Seasons
During December, the northern hemisphere tilts away
from the Sun. The more direct sunlight in the
southern hemisphere heats it up more than the
northern hemisphere, where it is now Winter.
Seasons
During Autumn and Spring, the Sun shines on both
hemispheres of the Earth equally which results in the
mild weather associated with those seasons.
• http://www.mesoscale.iastate.edu/agron206/ani
mations/01_EarthSun.html
• http://www.educypedia.be/education/spacejavae
arth.htm
• http://www.classzone.com/books/earth_science/t
erc/content/visualizations/es1704/es1704page0
1.cfm?chapter_no=visualization
Sun’s Azimuth
• http://www.astro.uiuc.edu/projects/data/Se
asons/index.html
Precession
Precession
• The Earth's rotation axis is not fixed in space.
Like a rotating toy top, the direction of the
rotation axis executes a slow precession with a
period of 26,000 years
Precession
• http://www.cs.sbcc.cc.ca.us/~physics/flash
/LengthofDay.swf
Precession
Thus, Polaris will not always be the Pole Star
or North Star. The Earth's rotation axis
happens to be pointing almost exactly at
Polaris now, but in 13,000 years the precession
of the rotation axis will mean that the bright
star Vega in the constellation Lyra will be
approximately at the North Celestial Pole
(which is perpendicular to the celestial
equator), while in 26,000 more years Polaris
will once again be the Pole Star.
Precession
Since the rotation axis is precessing in space, the
orientation of the Celestial Equator (which lies in the
same plane as the terrestrial equator) also precesses
with the same period. This means that the position of
the equinoxes is changing slowly with respect to the
background stars. This precession of the equinoxes
means that the right ascension and declination of
objects changes very slowly over a 26,000 year
period. This effect is negligibly small for casual
observing, but is an important correction for precise
observations.
Precession
Because of the precession of the equinoxes,
the vernal equinox moves through all the
constellations of the Zodiac over the 26,000
year precession period. Presently the vernal
equinox is in the constellation Pisces and is
slowly approaching Aquarius.
Precession
Around the year 130 BC, Hipparchus compared
ancient observations to his own and concluded that in
the preceding 169 years heavenly bodies had moved
by 2 degrees. How could Hipparchus know the
position of the Sun among the stars so exactly, when
stars are not visible in the daytime? By using not the
Sun but the shadow cast by the Earth on the moon,
during an eclipse of the Moon! During an eclipse,
Sun, Earth and Moon form a straight line, and
therefore the center of the Earth's shadow is at the
point on the celestial sphere, which is exactly
opposite that of the Sun.
Precession
Hipparchus concluded that the intersection marking
the equinox slowly crept forward along the ecliptic
(the plain defined by the Earth’s orbit around the
Sun), and called that motion "the precession of the
equinoxes. " The rate is about one full circle in 26
000 years. In ancient times the intersection marking
the spring equinox was in the constellation of Aries,
the ram, and for that reason the intersection
(wherever it might be) is still sometimes called "the
first point in Aries.
Precession
Around the year 1 it moved into the
constellation of Pisces and currently it is again
in transition, to the constellation of Aquarius,
the water carrier. If you ever heard the song
"The dawning of the age of Aquarius" from the
musical "Hair," that is what it is all about. To
believers of astrology, the "dawning of the age
of Aquarius" is a great portent marking the
beginning of a completely new era.
Precession
Warm Up
1.
2.
3.
4.
What are the eight phases of the moon?
What time does the full moon rise?
What time does the full moon set?
What time is the full moon straight
overhead?
Lunar Cycles
Lunar Cycles
The moon goes through the following phases
every 30 days. These phase changes always
occur from right to left.
• http://jove.geol.niu.edu/faculty/stoddard/JA
VA/moonphase.html
Lunar Cycles
•
The initial phase is called the new moon.
The new moon is completely dark.
•
As light begins to cover more and more of
the moon’s surface, the moon is said to be
waxing.
•
As darkness begins to cover more and more
of the full moon’s surface, the moon is said to
be waning.
Lunar Cycles
• The phase of the Moon can tell you the time of
day. For example, because a full Moon is seen
when the Moon is on the opposite side of the
Earth from the Sun, an observer on the Earth
will see the Moon rise just as the Sun sets. The
next day, the Moon will rise approximately
one hour later (because the Moon will have
moved farther along on its orbit). This means
that a waning half Moon will rise at midnight,
a new moon at dawn, etc...
Warm Up
1. List and diagram the eight phases of the moon.
2. Define waxing and waning.
3. You see the full moon just rising above the horizon.
What time is it?
4. Do we ever see the new moon? Why or why not?
5. You see the first quarter moon setting. What time is
it? What time will it rise?
6. You see the third quarter moon just rising above the
horizon. What time is it? What time will it set?
Warm Up-09/26/13
The last new moon was------------!
1. What is the current phase of the moon?
2. What time does it rise? Set?
3. It is 3 PM and the moon is straight overhead, what
is the moon phase? What time did it rise and set?
4. It is 6 PM and the moon is just rising, what is its
phase? What time will it set?
5. It is 3 AM and the moon is just setting, what is its
phase? What time did it rise?
6. What time does the waxing crescent rise and set?
7. What time does the new moon rise and set?
8. How can you differentiate the 1st quarter moon
from the 3rd quarter moon?
Creating a White Sheet!
What topics should be included?
What specific information should be listed
under each topic?
Do I need any math formulas?
Do I know how to use the math formulas?
Eclipses
http://sunearth.gsfc.nasa.gov/eclipse/OH/OH2006.html
The Two Types of Eclipses:
Solar eclipses- When
the Sun grows dark
when covered by the
moon and…
Lunar eclipses- When
the moon grows dark
when covered by the
shadow of the Earth.
NASA Eclipse Web Site
• http://eclipse.gsfc.nasa.gov/eclipse.html
Lunar eclipses
Solar eclipses
•
•
•
•
There are three kinds of solar eclipses:
Total eclipse
Partial eclipse and
Annular eclipse
Solar eclipses
Total Eclipse
Total Eclipse
During a total eclipse, the moon completely
covers the Sun and all you can see is the Sun’s
corona. This only occurs when the moon is a
certain distance from the Earth.
The moon castes two kinds of shadows on the
Earth’s surface:
The umbra: The dark, internal portion of the
shadow and …
The penumbra: The lighter shadow formed
outside the umbra.
Partial Eclipse
Partial Eclipse
During partial eclipses, the sky never darkens
and the moon never completely covers the
Sun. These photographs were taken during a
partial eclipse and show some of the strange
effects to shadows caused by the eclipse.
Annular Eclipse
Annular Eclipse
When the moon is farther away during a “total
eclipse” alignment, an annular eclipse occurs.
During an annular eclipse, the moon passed in
front of the Sun, but because it is further away
from the Earth, it casts a smaller shadow.
During an annular eclipse the Sun is not
completely obscured by the moon and the
fringes of the Sun may be seen.
The Earth’s Moon
The End