The Sun was shining on the sea, Shining with all his might; He did his very best to make The 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
Homework #1: due TODAY Homework #2: due Monday, September 12 Review Questions: 8, 9, 11 Discussion Question: 3 Learning to look: 3 } Chapter 2 Review Question: 1 Problems: 2, 3 Learning to look: 4 } Chapter 3 Last Day to Add: September 13 Quiz #1: Monday, September 12 Chapters 1 and 2 Extra Credit: know what phase the Moon is in that day
Outline I. 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 Sphere Vocabulary: longitude/latitude celestial sphere celestial pole/equator horizon/zenith constellation ecliptic/zodiac equinox solstice
Review 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
Based on this figure, in what constellation is the sun on July 1 each year? 1. Gemini 2. Sagittarius 3. Cancer 4. Leo 5. Aquarius
The Seasons
The Seasons Sun is higher in the sky at noon in the summer Day-light lasts longer
The Seasons Sun is higher in the sky at noon in the summer Day-light lasts longer Sun is lower in the sky at noon in the winter Night-time lasts longer
The Seasons
The Seasons As it orbits the Sun, the Earth maintains its orientation, at least on timescales of hundreds of years.
The Seasons Equinox Equinox As it orbits the Sun, the Earth maintains its orientation, at least on timescales of hundreds of years.
The Seasons Equinox Solstice Solstice Equinox As it orbits the Sun, the Earth maintains its orientation, at least on timescales of hundreds of years.
Rising/Setting Sun Where the Sun rises and sets also changes with the seasons.
The Seasons Equinox: 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: Outline I. 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 Radius of Earth = Radius of Moon = Ratio = 6.38 x 10 3 km 1.74 x 10 3 km 3.67:1
The Scale of the Earth/Moon System Radius of Earth = Radius of Moon = Ratio = 6.38 x 10 3 km 1.74 x 10 3 km 3.67:1 Diameter of Earth = Distance to Moon = = 2 x 6.38 x 10 3 km 384403 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 Activity with styrofoam balls (Moon) and light (Sun) 1. Your head is the Earth 2. Moon orbits in counter-clockwise direction 3. Place Moon in direction of Sun to begin 4. 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.
Phases of the Moon
Labeling the Phases New Waxing Crescent First Quarter Waxing Gibbous } right side illuminated Full Waning Gibbous Third Quarter Waning Crescent } left side illuminated New
Phases of the Moon Can you ever see the Moon during the daytime? If not, why? If so, what phases?
Phases of the Moon Can you ever see the Moon during the daytime? If not, why? If so, what phases? Is there any phase of the Moon that you can never see at night?
Phases of the Moon Can you ever see the Moon during the daytime? If not, why? If so, what phases? 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 dinnertime. 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 dinnertime. 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 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 The Earth exerts tidal forces on the moon s rocky interior. It is rotating with the same period around its axis as it is orbiting Earth (tidally locked).
The Moon s Orbit The Earth exerts tidal forces on the moon s rocky interior. 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 Orbit The Earth exerts tidal forces on the moon s rocky interior. 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 Orbit Moon 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
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