Moon Phases

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Moon Phases Eclipses

• What patterns, motions, and events do we notice
  in the sky?
• What theories can we create to explain them?
• How can these theories be tested?

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The last LUNAR eclipse YOU might have seen
September 28, 2015
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The next LUNAR eclipse YOU can see
March 23, 2016
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The last TOTAL SOLAR eclipse YOU could have seen
Monday morning, 21 August 2017
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The nearby TOTAL SOLAR eclipse YOU might have
seen
August 21 2017
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The next TOTAL SOLAR eclipse YOU hopefully will
see!
August 12 2045
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A really nearby TOTAL SOLAR eclipse YOU might
see
August 12 2045
Chabot College
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Observations of the Moon

• Sequence of phases every moonth
• We always see the same face

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Observations of the Moon

• Occasionally turns dark gray even red!
• Can seem bigger next to the horizon!

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• Phases repeat 30 days
• A moonth of time
• Tied to religious calendars around the globe
• Ramadan
• Chinese New Year
• Easter
• Rosh Hashanah
• Gudi Padwa Vasant Panchami

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Observations of the Moon

• Sequence of repeated phases over moonth
• Sunlight reflecting off Moon that is visible to
  us
• NOT Earths shadow!!

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Observations of the Moon

• IS the phase the same on the same day around the
  world?
• Do people in London see the same phase as we do
  in Hayward?

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Observations of the Moon

• IS the phase the same on the same day around the
  world?
• Most people would say NO!
• They are wrong!
• Compare times
• For Earth to rotate hours
• For the Moon to move change phase days

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Observations of the Moon

• Do people in both hemispheres see the same view?
• Does an observer at Chabot see the same thing as
  someone in Santiago, Chile?
• Most people would say erYES?
• They are wrong!

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• Phases are reversed in Southern Hemisphere!
• Same side of moon is still lit by the sun
• Observation from down under reverses view.

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• Northern Hemisphere Phases!

• Southern Hemisphere Phases!

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Seeing the moon from different places on Earth!
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Seeing the moon from different places on Earth!
Northern Hemisphere
Southern Hemisphere
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The Moon Illusion!
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The Moon Illusion!
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What theories can we develop?

• WHY does the moon seem larger?
• Because it IS larger?
• Because it is an illusion
• We see horizon different than zenith?
• We dont have a reference for Moon when its
  higher in the sky?
• How can you TEST these hypotheses?

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The Moon Illusion!
The Moon DOES vary in distance.
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The Moon Illusion!
.but not over a few hours!
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The Moon Illusion!
Perhaps we dont see the sky as symmetric the
horizon is farther away than the sky above us?
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Solar Eclipses

• Occur at NEW moon phase
• While partial, a bite out of the Sun
• Last 1 hours
• IF total
• Sky goes dark for a few minutes
• See planets and stars near the sun
• See Suns corona and chromosphere

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• Shadow of
• the moon
• covers small
• oval on Earth

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Corona
Chromosphere
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Annual Solar Eclipse

• Time-lapse series of photos
• What time of day?
• How long did this take?
• Hint Northern Hemisphere!

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Lunar Eclipses

• Occur at FULL moon phase
• The Moon looks full, but dim
• The Earths curved shadow falls across the moon
• Last 2 hours
• IF total
• Moon can look red for an hour

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At the start of a lunar eclipse, you can see the
Earths Shape through its shadow
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Lunar Eclipse Time-Lapse
Note the curved shadow of the Earth across the
moon.
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Predicting Eclipses

• Eclipse seasons
• About twice a year
• Always at least (2) eclipses
• One of each (lunar solar)
• About 2 weeks apart
• Pattern repeats about 18 years for location and
  type

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Eclipse Seasons
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The next total LUNAR eclipse YOU can see
Monday night, 21 January 2019
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The next total LUNAR eclipse