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 last LUNAR eclipse YOU might have seen… September 28, 2015
The next LUNAR eclipse YOU can see… March 23, 2016
The last TOTAL SOLAR eclipse YOU could have seen… Monday morning, 21 August 2017
The “nearby” TOTAL SOLAR eclipse YOU might have seen… August 21 2017
The next TOTAL SOLAR eclipse YOU hopefully will see!… August 12 2045
A really “nearby” TOTAL SOLAR eclipse YOU might see… August 12 2045 Chabot College
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 days A “moonth” of time Tied to religious calendars around the globe Ramadan Chinese New Year Easter Rosh Hashanah Gudi Padwa & Vasant Panchami
Observations of the Moon Sequence of repeated phases over ~ “moonth” Sunlight reflecting off Moon that is visible to us NOT Earth’s shadow!!
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: hours For 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.
Northern Hemisphere Phases! Southern Hemisphere Phases!
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 DOES vary in distance…. The Moon Illusion! The Moon DOES vary in distance….
….but not over a few hours! 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 minutes See planets and stars near the sun See Sun’s corona and chromosphere
Shadow of the moon covers small oval on Earth
FIGURE 1-26 A Total Eclipse of the Sun During a total solar eclipse, the Moon completely covers the Sun’s disk, and the solar corona can be photographed. This halo of hot gases extends for millions of kilometers into space. This gorgeous image is a composite of several taken in Chisamba, Zambia, during the June 21, 2001, solar eclipse. (F. Espenak)
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 year Always 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 total LUNAR eclipse YOU can see… Monday night, 21 January 2019
The next total LUNAR eclipse