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?
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.
Dec 31, 2015
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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?
The next LUNAR eclipse YOU can see…
Sunday night, 27 September 2015
The next TOTAL SOLAR eclipse YOU can see…
Monday morning, 21 August 2017
The next “nearby” TOTAL SOLAR eclipse YOU can see…
August 21 2017
Observations of the Moon Sequence of phases
every “moonth”
We always see the same “face”
Observations of the Moon Occasionally turns dark
gray & even red!
Can seem bigger next to the horizon!
Phases repeat ~30 daysA “moonth” of time
Tied to religious calendars around the globeRamadanChinese New YearEasterRosh HashanahGudi Padwa & Vasant
Panchami
Observations of the Moon
A sequence of repeated phases over about a “moonth”
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?
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: hoursFor the Moon to move & change phase: days
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…… er…YES?
They are wrong!
Phases are “reversed” in Southern Hemisphere!
Same side of moon is still lit by the sun
Observation from “down under” reverses view.
Seeing the moon from different places on Earth!
Seeing the moon from different places on Earth!
Northern Hemisphere Southern Hemisphere
The Moon Illusion!
The Moon Illusion!
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 don’t have a “reference” for Moon when it’s
higher in the sky?
How can you TEST these hypotheses?
The Moon Illusion!
The Moon DOES vary in distance….
The Moon Illusion!
….but not over a few hours!
The Moon Illusion!
Perhaps… we don’t see the sky as symmetric – the horizon is farther away than the sky above us?
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 minutesSee planets and stars near the sunSee Sun’s corona and chromosphere
Shadow of
the moon
covers small
oval on Earth
Corona
Chromosphere
Annual Solar Eclipse
Time-lapse series of photos
-What time of day?
-How long did this take?
Hint: Northern Hemisphere!
Lunar Eclipses Occur at FULL moon phase
The Moon looks full, but dim
The Earth’s curved shadow falls across the moon
Last 2+ hours
IF total…Moon can look red for an hour
At the start of a lunar eclipse, you can see the Earth’s Shape through its shadow…
Lunar Eclipse Time-Lapse
Note the curved shadow of the Earth across the moon.
Predicting Eclipses
Eclipse “seasons”About twice a yearAlways at least (2) eclipses
One of each (lunar + solar)About 2 weeks apart
Pattern repeats about 18 years for location and type
Eclipse “Seasons”
The next LUNAR eclipse YOU can see…
Sunday night, 27 September
2015
Sunday night, 27 September 2015
•Moon rises with partial eclipse already started
•Total beings 7:11 PM
•Max Eclipse 7:47
•Total Ends 8:23
•Partial Ends 9:27
•Then… just a full moon!
A really “nearby” TOTAL SOLAR eclipse YOU might see…
August 12 2045
Chabot College
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