Observational Astronomy 2

7/28/2019 Observational Astronomy 2

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19-Apr-13

IESO

Observational Astronomy

Part 2


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19-Apr-13

Sun-Moon-Earth System

Objectives

Identify the relative positions andmotions of Earth, the Sun, and theMoon

Describe the phases of the Moon.

Explain eclipses of the Sun and Moon.


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I. Motion

We are moving at a speed of mph around

the sun (and rotating about mph).


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I. Motion

We are moving at a speed of 67,000 mph around

the sun (and rotating about 1000 mph).


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I. Motion

A. Evidence of motion

How do we know there is motion?


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I. Motion

A. Evidence of motion1. Apparent motion of sun


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I. Motion


2. Apparent motion of moon

http://www.nasa.gov/vision/universe/watchtheskies/20jun_moonillusion.html


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I. Motion


2. Apparent motion of moon

3. Apparent motion of stars

http://www.sufism.org/society/articles/sema_camille.html


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I. Motion


B. Rate of motion

Each day the sun moves an apparent 360. This

means it appears to move /minute.


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I. Motion


B. Rate of motion

Each day the sun moves an apparent 360. This

means it appears to move 0.25 /minute.


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I. Motion


B. Rate of motion

C. How do we know Earth is moving?

. . .and not the rest of the universe?


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I. Motion


B. Rate of motion

C. How do we know Earth is moving?1. A Foucault pendulum

http://en.wikipedia.org/wiki/Foucault_pendulum
http://www.phys.unsw.edu.au/PHYSICS_!/FOUCAULT_PENDULUM/foucault_pendulum.html


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I. Motion


B. Rate of motion

C. How do we know Earth is moving?1. A Foucault pendulum

2. Coriolis effect

http://www.atmos.ucla.edu
http://www.atmos.ucla.edu/AS3/scrns/force2/Note02.htmlhttp://www.atmos.ucla.edu/AS3/scrns/force2/Note02.htmlhttp://www.csun.edu/~jte35633/multimedia/coriolis.mov


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II. Earths Tilt


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II. Earths Tilt

A. Earth moves in a plane called theecliptic


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II. Earths Tilt


B. Earths axis of rotation is not

perpendicular to its ecliptic

It tilts by .


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II. Earths Tilt




It tilts by 23.5.

23.5


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II. Earths Tilt




C. In the Northern hemisphere theSuns altitude in the sky is higher

in the .


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Altitudeis measured in degrees from the observers horizon to the object..


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II. Earths Tilt




C. In the Northern hemisphere theSuns altitude in the sky is higher

in the summer.


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II. Earths Tilt

D. The solstices


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II. Earths Tilt

D. The solstices1. Summer


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II. Earths Tilt


a. Longest day of the year (inNorthern hemisphere)


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II. Earths Tilt



b. Sun is directly overhead atTropic of Cancer (23.5 N)


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II. Earths Tilt




c. Occurs around June 21


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II. Earths Tilt




c. Occurs around June 21d. Sun never sets in Arctic circle


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Summer Solstice


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II. Earths Tilt


2. Winter


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II. Earths Tilt


2. Winter

a. Most hours of darkness (in N.hemisphere)


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II. Earths Tilt


2. Winter


b. Sun is directly overhead at

Tropic of Capricorn (23.5 S)


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II. Earths Tilt


2. Winter



Tropic of Capricorn (23.5 S)c. Occurs around December 21


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II. Earths Tilt


2. Winter



Tropic of Capricorn (23.5 S)c. Occurs around December 21

d. Sun never rises in Arctic circle


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Winter Solstice


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II. Earths Tilt


2. Winter

3. Equinoxes


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II. Earths Tilt


2. Winter

3. Equinoxes

a. Occur at midpoint betweensolstices


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II. Earths Tilt


2. Winter

3. Equinoxes


b. Sun directly overhead atequator


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II. Earths Tilt


2. Winter

3. Equinoxes


b. Sun directly overhead atequator

c. Both hemispheres receive equal

sunlight


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Self Check1. At which point is summer solstice?


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Self Check1. At which point is summer solstice?

2. At which point is the vernal equinox


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III. Phases of the Moon

G


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III. Phases of the MoonA. Names of the Phases

Go to

diagram

G


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1. New moon

The moon is between Earth and the Sunwe

dont see the lit surface

Go to

diagram

G


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1. New moon

2. Waxing crescent

Waxing means increasing

Go to

diagram

G t


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1. New moon

2. Waxing crescent

3. First quarter

Observed of the way through a lunar month

Go to

diagram

G t


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1. New moon

2. Waxing crescent

3. First quarter4. Waxing gibbous

Gibbous means more than but less than full

Go to

diagram

G t


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5. Full moon

The moon is on opposite sides of the Earth from

the Sunwe see the entire lit surface

Go to

diagram

G t


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5. Full moon

6. Waning gibbous

Waning means decreasing in size/intensity

Go to

diagram

Go to


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5. Full moon

6. Waning gibbous

7. Third quarter

Observed into the lunar month

Go to

diagram

Go to


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5. Full moon

6. Waning gibbous

7. Third quarter8. Waning crescent

Go to

diagram


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B. Synchronous Rotation

For each revolution of the moon it makes one

rotation.


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III. Phases of the MoonC. Timing


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1. It takes the moon about 27.3 days tocomplete its (a lunar month).

f


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1. It takes the moon about 27.3 days tocomplete its orbit (a lunar month).

2. During 24 hours the moon moves

1/27.3 of its orbit which = .

III Ph f h M


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1/27.3 of its orbit which = 13.

3. This means the Earth must rotatean extra 13 to catch up to themoon.

Each night the moonrise occurs about minutes

later.

III Ph f h M


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1/27.3 of its orbit which = 13.

3. This means the Earth must rotatean extra 13 to catch up to themoon.

Each night the moonrise occurs about 50 minutes

later.


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IV E li


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IV. Eclipses

IV E li


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IV. EclipsesA. Solar Eclipse

IV E li


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1. The moon creates a shadow thatcovers part of the Earth

June 29, 2006 Solar Eclipse

IV E li


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a. The Umbra is the darker, inner

part of the shadow.

If the umbra passes over your location you see no

sun ( Eclipse)

IV E li


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part of the shadow.

If the umbra passes over your location you see no

sun (Total Eclipse)

IV E li


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part of the shadow.b. The Penumbra is the lighter,

outer shadow.

If the penumbra passes over your location you see

some of the sun ( Eclipse)

IV E li


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part of the shadow.b. The Penumbra is the lighter,

outer shadow.

If the penumbra passes over your location you see

some of the sun (Partial Eclipse)


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Photos Taken During

Partial Eclipse

S l E li
http://science.nasa.gov/spaceweather/eclipses/gallery_10june02.html


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Solar Eclipse

IV E li


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B. Annular Eclipse

Occurs when the Earth/Moon system areseparated by maximum distance.

IV E li


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B. Annular Eclipse

Furthest distance between Moon and Earth.

1. Apogee

IV Eclipses


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B. Annular Eclipse

Smallest distance between Moon and Earth.

1. Apogee

2. Perigee

IV Eclipses


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IV. EclipsesC. Lunar Eclipse

Moon is partially blocked by the .

IV Eclipses


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IV. Eclipses

Moon is partially blocked by the Sun.

C. Lunar Eclipse

IV Eclipses


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IV. Eclipses

1. These last longer than Solar eclipsesbecause. . .

C. Lunar Eclipse

IV Eclipses


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IV. Eclipses

1. These last longer than Solar eclipsesbecause. . .

2. Even though moon passes through

umbra, it is not completely darkbecause. . .

C. Lunar Eclipse


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The End

The Moons Phases (from above)


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The Moons Phases (from above)

Observational Astronomy 2

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