the sun was shining on the sea, shining with all his might ... · the sun was shining on the sea,...

The Sun was shining on the sea,Shining with all his might;

He did his very best to makeThe billows smooth and bright-And this was odd because it was

The middle of the night.

from “The Walrus and the Carpenter” Through the Looking-Glass -- Lewis Carroll

Wednesday, September 7, 2011

Homework #1: due TODAY

Homework #2: due Monday, September 12Review Questions: 8, 9, 11Discussion Question: 3Learning to look: 3

Review Question: 1Problems: 2, 3Learning to look: 4

Last Day to Add: September 13

Quiz #1: Monday, September 12Chapters 1 and 2Extra Credit: know what phase the Moon is in that day

} Chapter 2

} Chapter 3


OutlineI. The Stars A. Constellations B. The Names of the Stars C. The Brightness of Stars D. Magnitude and Intensity

II. The Sky as a Dome Overhead A. The Celestial Sphere B. Sky Charts

III. Cycles in the Sky A. Diurnal Motion B. Annual Motion: Stars, Sun C. The Seasons D. The Moving Planets


The Celestial SphereVocabulary:

• longitude/latitude• celestial sphere• celestial pole/equator• horizon/zenith• constellation• ecliptic/zodiac• equinox• solstice


1) Sketch path of setting stars viewed from SJSU and then from Rio de Janeiro.

2) Earth spins counter-clockwise. What direction does it orbit the Sun?

3) What causes seasons?

4) Solstice, Equinox

Review


Based on this figure, in what constellation is the sun on July 1 each year?

1. Gemini2. Sagittarius3. Cancer4. Leo5. Aquarius


The Seasons


The Seasons

Sun is higher in the sky at noon in the

summerDay-light lasts

longerWednesday, September 7, 2011

The Seasons

Sun is higher in the sky at noon in the

summerDay-light lasts

longer

Sun is lower in the sky at noon in the

winterNight-time lasts

longerWednesday, September 7, 2011

The Seasons


The Seasons

As it orbits the Sun, the Earth maintains its orientation, at least on timescales of hundreds of

years.


The Seasons


years.

Equinox

Equinox


The Seasons


years.

Equinox

Equinox

Solstice

Solstice


Rising/Setting Sun

Where the Sun rises and sets also changes with the seasons.


The SeasonsEquinox:

• Occurs March 21 (vernal) and September 21 (autumnal)• length of day/night is 12/12 everywhere on Earth• Sun rises/sets due east/west for everyone

Solstice:• June 21: summer solstice in northern hemisphere (longest day-light of year); Sun rises/sets north of east/west• December 21: winter solstice in northern hemisphere (longest night-time of year); Sun rises/sets south of east/west• swapped in southern hemisphere!


Chapter 3: OutlineI. The Scale of the Earth/Moon System

II. The Changeable Moon A. The Motion of the Moon B. The Cycle of Phases

III. Lunar Eclipses A. Earth's Shadow B. Total Lunar Eclipses C. Partial and Penumbral Lunar Eclipses

IV. Solar Eclipses A. The Angular Diameter of the Sun and Moon B. The Moon's Shadow C. Features of Solar Eclipses D. Observing an Eclipse


The Scale of the Earth/Moon System

6.38 x 103 km1.74 x 103 km3.67:1

Radius of Earth =Radius of Moon = Ratio =


The Scale of the Earth/Moon System

6.38 x 103 km1.74 x 103 km3.67:1

Radius of Earth =Radius of Moon = Ratio =

Diameter of Earth =Distance to Moon = =

2 x 6.38 x 103 km384403 km~ 30 earth diameters


Phases of the Moon

Picture taken of Earth/Moon from 6.2 million km away on December 16, 1992, by Galileo spacecraft on its way to Jupiter.


Phases of the Moon


Phases of the Moon

1. Your head is the Earth2. Moon orbits in counter-clockwise direction3. Place Moon in direction of Sun to begin4. Move Moon 45 degrees at a time in its orbit.

At each position, sketch the Moon.

example:

Don’t let your head (or that of another student!) get in the way.

Activity with styrofoam balls (Moon) and light (Sun)


Phases of the Moon


Labeling the Phases

New

Waxing CrescentFirst QuarterWaxing Gibbous

Full

Waning GibbousThird QuarterWaning Crescent

New

} right side illuminated

} left side illuminated


Phases of the Moon

Can you ever see the Moon during the daytime? If not, why? If so, what phases?


Phases of the Moon


Is there any phase of the Moon that you can never see at night?


Phases of the Moon


Is there any phase of the Moon that you can never see at night?

The full moon is at its highest position in the sky. About what time is it?


Phases of the Moon


Phases of the Moon

You see the Moon rising in the East at dinner-time. What phase is the Moon in?

A third quarter moon is setting in the West. About what time is it?


Phases of the Moon

You see the Moon rising in the East at dinner-time. What phase is the Moon in?

A third quarter moon is setting in the West. About what time is it?

The first quarter moon is rising in the east. About what time is it?


The Moon’s Orbit

Synodic Period = 29.53 days (relative to Sun)Sidereal Period = 27.32 days (relative to stars)


The Moon’s Orbit


The Moon’s Orbit

The Earth exerts tidal forces on the moon’s rocky interior.


The Moon’s Orbit


→ It is rotating with the same period around its axis as it is orbiting Earth (tidally locked).


The Moon’s Orbit


→ It is rotating with the same period around its axis as it is orbiting Earth (tidally locked).

→ We always see the same side of the moon facing Earth.


The Moon’s OrbitMoon’s orbit about Earth is not perfectly circular. The consequence is that the Moon gets slightly larger and smaller in the sky. The change is only about 12%!


The Moon’s Orbit

Inclination of orbital plane relative to the ecliptic is 5.14 degrees.

= ~10 moon diameters

From: http://www.astronomynotes.com/nakedeye/s13.htm


http://www.astronomynotes.com/nakedeye/s13.htm

http://www.astronomynotes.com/nakedeye/s13.htm

When I heard the learn’d astronomer,When the proofs, the figures, were ranged in columns before me,When I was shown the charts and diagrams, to add, divide, and measure them,When I sitting heard the astronomer where he lectured with much applause in the lecture room,How soon unaccountable I became tired and sick,Till rising and gliding out I wander’d off by myself,In the mystical moist night air, and from time to time,Look’d up in perfect silence at the stars. - Walt Whitman


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