Plan For Today �  Finish up from last time: expanding universe

�  Earth’s orbits: solstice, equinox, seasons

�  Begin Phases of the moon if time permits…

Homework 2 due on Tuesday

How Big is Big? On a 1:10,000,000,000 scale, what is the approximate size of:

�  The sun?

�  The earth and other planets?

�  The distance from the sun to earth?

�  The distance from the sun to neptune?

�  The distance of one light year?

�  The distance of one Astronomical unit (AU)?

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So, why are things so far, if gravity pulls things together?

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Scales of Time – Starts with the Big Bang

Edwin Hubble discovered that:

1.  Practically every galaxy outside of local group is moving away from us

2.  The further away the galaxy is, the faster it moves away.

Why is this?

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Scales of Time – Starts with the Big Bang

Raisin Cake Analogy

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SEASONS! �  Why are there different seasons?

Earth rotates and orbits at the same time

Image taken from earthgauge.net

At Winter Solstice, no direct sun at North Pole. Shortest day of year in Northern

Hemisphere

At Summer Solstice, direct sun all day long at North Pole. Longest day of the

year in Northern Hemisphere

Equinox – sun rises and sets directly East/West. Day and night = 12 hours

Activity on Seasons

Plan For Today �  Phases of the Moon

Homework:

Homework 2

Review Questions

What causes the seasons? a.  In summer the earth is closer to the sun (because

the orbits in an elliptical pattern).

b.  In summer the tilt of the earth’s axis makes the part of the earth we are on closer to the sun.

c.  In summer the sun is up for more hours.

d.  In summer the sun climbs higher in the sky so its rays hit the ground more directly.

e.  Both c and d

If the tilt of the earth’s axis to its orbital plane was 40 degrees instead of 23 ½ degrees but its distance to the sun remained the same, what would happen to the seasons?

a.  They wouldn’t change much.

b.  They would become less extreme – winter and summer would be more alike.

c.  They would become more extreme – winter would be colder and summer would be hotter.

d.  The whole earth would get colder.

e.  The whole earth would get warmer.

The Phases of the Moon

- Vocab

The Phases of the Moon - Vocab

1st Quarter

3rd Quarter

Waxing Gibbous

Waning Crescent

New Moon

Full Moon

WAXING

WANING

“Wax On, Wane off”

Phases of the Moon DEMO

Phases of the Moon DEMO (with orange)

Computer Demo:

http://media.pearsoncmg.com/aw/aw_bennett_cosmic_4/tcp4ma/Tutorials/flash/MoonPhases/

MoonPhases.html

Which Moon position (A-E) best corresponds with the Moon phase shown?

Sketch how the Moon would appear at each of the other four positions.

Shade the illuminated portion of the Moon at each location

Which Moon position (A-D) best corresponds with the Moon phase

shown?

How much of the entire Moon’s surface is illuminated by the Sun during this

phase?

a.  None of the surface is illuminated.

b.  Less than half of the surface is illuminated.

c.  Half of the surface is illuminated.

d.  More than half of the surface is illuminated.

e.  All of the surface is illuminated.

How much of the Moon’s illuminated surface is visible from Earth for this

phase of the Moon? a.  None of the surface (visible from Earth) is

illuminated.

b.  Less than half of the surface (visible from Earth) is illuminated.

c.  Half of the surface (visible from Earth) is illuminated.

d.  More than half of the surface (visible from Earth) is illuminated.

e.  All of the surface (visible from Earth) is illuminated

Would your answers to the last two questions change if the Moon were in

the third quarter phase rather than the new moon phase? Explain.

Student 1: The phase of the Moon depends on how the Moon, Sun, and Earth are aligned with one another. During some alignments only a small portion of the Moon’s surface will receive light from the Sun, in which case we would see a crescent Moon.

Student 2: I disagree. The Moon would always get the same amount of sunlight; it’s just that in some alignments Earth casts a larger shadow on the Moon. That’s why the Moon isn’t always a full Moon.

Do you agree or disagree with either or both students? Discuss with the person sitting next to you.

Predicting Moon Phases

If the Moon is full tonight, will the Moon be waxing or waning one week later?

a.  Waxing

b.  Waning

If the Moon is full tonight, which side of the Moon will appear illuminated in one

week?

a.  Right

b.  Left

The Phases of the Moon - Vocab

Full Moon

Where would you look to see the full Moon when it starts to rise?

a.  On the eastern horizon

b.  On the western horizon

c.  High in the sky

d.  In the southern sky

What time would a full Moon rise?

a.  6 AM

b.  Noon

c.  6 PM

d.  Midnight

Where would you look to see the Sun when the full Moon starts to rise?

a.  On the eastern horizon

b.  On the western horizon

c.  High in the sky

d.  In the southern sky

Where would you look to see the new Moon, if it were visible, when it starts to

rise? a.  On the eastern horizon

b.  On the western horizon

c.  High in the sky

d.  In the southern sky

What time would a new Moon rise?

a.  6 AM

b.  Noon

c.  6 PM

d.  Midnight

If the Moon is a new Moon when it rises, which Moon will it be when it sets?

a.  Full moon

b.  1st quarter moon

c.  New Moon

d.  3rd quarter moon

e.  Waxing Gibbous

Think through the next page of questions and answer them on your own. Phase?

What time is Moon high in sky? What time will Moon rise? What time will Moon set?

At what time would you look to see a first-quarter Moon at its highest position

in the sky? a.  6 AM

b.  Noon

c.  6 PM

d.  Midnight

If the Sun set below your western horizon about 2 hours ago, and the Moon is barely visible on the eastern horizon, what phase would the Moon be in at this time and location?

Think through the remaining question and answer it on your own.

Sliver of Moon is visible in early morning.

What phase is it and where is it in the sky?

Wrap up Questions

You observe a full moon rising in the east. Which image shown below best represents how the Moon will appear

when it sets?

What time is it when this Moon phase rises above the horizon?

a.  Midnight

b.  3 AM

c.  Noon

d.  3 PM

e.  9 PM

Which phase of the Moon rises in the east as the Sun rises in the east?

a.  First quarter

b.  Gibbous

c.  Full

d.  Third quarter

e.  New

During the full moon phase, how much of the Moon’s surface is being

illuminated by sunlight?

The Faces of the Moon �  We always see the same face of the moon. Why?

DEMO