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Week 2 Earthly Phenomena: Seasons Lunar Phases Solar and Lunar Eclipses Tides Reading: E2, E3, 5.2 (12 pages)

Week 2 Earthly Phenomena: Seasons Lunar Phases Solar and Lunar Eclipses Tides Reading: E2, E3, 5.2 (12 pages)

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Week 2

Earthly Phenomena:

Seasons

Lunar Phases

Solar and Lunar Eclipses

Tides

Reading: E2, E3, 5.2 (12 pages)

Quick Quiz

1) If new Moon fell on March 2nd, what is the Moon's phase on March 14th? A) waxing crescent B) first quarter C) waxing gibbous D) full E) waning crescent

2) Only people in the Moon's umbral shadow can see a total solar eclipse. T/F

3) What will occur when the full Moon is on the ecliptic? ) A) a total lunar eclipse B) a total solar eclipse C) a partial solar eclipse D) an annular lunar eclipse E) a partial lunar eclipse if the Moon is at perigee

• Rotation of the Earth

• Revolution (orbit) of the Earth

• Revolution (orbit) of the Moon

• Rotation of the Moon

Rotation of the Earth

Earth’s rotation around its axis:

• Causes night and day (Solar day = average time between consecutive “noontimes”).

• Causes (apparent) motion of the stars

Rotation of the Earth

Earth’s rotation around its axis:

• Causes night and day (Solar day = average time between consecutive “noontimes”).

• Causes (apparent) motion of the stars

Revolution (Orbit) of the Earth

• The revolution of the Earth around the Sun

defines the year (365.2425 days).

• Earth’s motion around the

Sun traces a path on the

Celestial Sphere called the

ecliptic.

• The Earth’s revolution

around the Sun also causes

the seasons. How?

TPS: What causes the seasons?

A. The changing distance between the Earth and the Sun?

B. The 23.5 degree tilt of the Earth’s axis?

Hint: Although it is Winter in the Northern Hemisphere right now, it is Summer in the Southern Hemisphere.

Spring in Northern Hemisphere

Fall in Southern HemisphereWinter in Northern Hemisphere

Summer in Southern Hemisphere

Summer in Northern Hemisphere

Winter in Southern HemisphereFall in Northern Hemisphere

Spring in Southern Hemisphere

NP

SP

Why exactly?The Sun is lower in the sky in the Winter.

The light from the Sun is diluted.

Short Winter days mean less overall light shining on that part of the Earth.

Summer Winter

Earth as Seen from the Sun

North American Summer

North American Winter

Equinoxes – Sun crosses the celestial equator (twice – Spring and Fall)

Solstices – Sun’s farthest northerly or southerly position (Summer or Winter)

Ecliptic – Path that the Sun follows in the sky

Seasons• Ecliptic is plane of Earth’s path around Sun; at 23.5° to celestial equator

• Northernmost point (above celestial equator) is summer solstice; southernmost is winter solstice; points where path cross celestial equator are vernal and autumnal equinoxes

Seasons • Combination of day length and sunlight angle gives seasons

• Time from one vernal equinox to next is tropical year

“Path of the Sun”

Revolution of the Moon

The Moon’s revolution around the Earth causes:

• Lunar phases

• Eclipses

• Tides

Lunar Phases

What causes the phases of the Moon?

Is this crescent Moon caused by

A. Sunlight shining mostly on the “far side” of the Moon?

B. The shadow of the Earth?

MonthsThe Moon takes about 29.5 days to go through whole cycle of phases – synodic month

Phases are due to different amounts of sunlit portion being visible from Earth

Time to make full 360° around Earth, sidereal month, is about 2 days shorter

Waxing crescent

First quarter

Full Moon

Waning gibbous

Third quarter

Waxing gibbous

New Moon

Waning crescent

Waxing crescent

New Moon

Waning crescent

First quarter

Waxing crescent

First quarter

Full Moon

Waning gibbous

Third quarter

Waxing gibbous

New Moon

Waning crescent

Name of Phase Fraction Illuminated (Apparent) Side Illuminated Rises Sets

New Moon 0 None 6am 6pm

Waxing Crescent ¼ West (Right) 9am 9pm

First Quarter ½ West (Right) Noon Midnight

Waxing Gibbous ¾ West (Right) 3pm 3am

Full Moon 1 All 6pm 6am

Waning Gibbous ¾ East (Left) 9pm 9am

Third Quarter ½ East (Left) Midnight Noon

Waning Crescent ¼ East (Left) 3am 3pm

 

Lunar Phases Movie