Download Understanding Lunar Phases and Eclipses and more Study notes Astronomy in PDF only on Docsity! ©2003 G. Gonzalez Lunar Phases -- The Movie Lunar Eclipse -- The Movie The phases of the Moon. Names of the lunar phases Phases of the Moon’s 29.5 day cycle • new • crescent • first quarter • gibbous • full • gibbous • last quarter • crescent waxing waning Waxing Gibbous Lunar Eclipse Lunar eclipses versus Lunar phases Note the different shapes of the Moon’s terminator in the two images. Therefore, the Moon’s phases and eclipses are due to two different phenomena, and the Moon does not go through its phases during an eclipse, nor visa versa. Astro term: The terminator is the boundary between lit and dark regions. How do these images differ? Let’s do an experiment So, how do we test this idea? Let’s consider the following model to explain the Moon’s phases: the phases are due to the our changing perspective of a half-illuminated sphere. yy
Draw what you see... se
New Moon Full Moon Waning Crescent Last Quarter Waning Gibbous Waxing GibbousWaxing Crescent First Quarter
Earth
Diagram above shows Earth-Moon system drawn to scale.
View of the
Moon as seen
from Earth
Sidereal vs. Synodic months New Moon T=0d T=27.3d (Sidereal) T=29.5d (Synodic) Sunset Sunrise MidnightNoon Moonrise & Moonset at 1st Quarter Where is the Moon in the sky at sunset? N Note that the illuminated half of the Moon faces the Sun.
Waning Crescent
Rise: 3 AM
Meridian: 9 AM Third Quarter
he Set: 3 pM Rise: midnight
S Meridian: 6 a.m
New Moon ” oon
Rise: 6 am
Meridian: noon ~
Set: 6 pm.
a
a;
Waxing Crescent
Rise: 9 AM
Meridian: 3 pm
Set: 9pm
First Quarter
Rise: noon
Meridian: 6 Pm
Set: midnight
Rise and set times
are approximate.
Rise: 3 PM
Set: 3. AM.
Copyright © 2004 Pearson Education, publishing as Addison Wesley.
Waxing Gibbous
The photos show how she would
see the lunar phases from Earth
as she turns to face the Moon in
each position as it orbits Earth.
Waning Gibbous
Rise: 9 PM
Meridian: 3 AM
Set: 9AM
Full Moon
Rise: 6 PM
Meridian: midnight
Set: 6AM
Meridian: 9 Pm
Sun’s apparent path on the sky March 21 June 21 September 21 December 21 Ecliptic E S C.E. Test your understanding 3 You need to know how to answer questions of the following type: -When does the full Moon rise? -Will the full Moon be low or high in the evening sky in the winter as seen from Ames? The Moon on the celestial sphere NCP What time of year is shown? What phase is the Moon? Is it visible from the North Pole on Earth? CEDiurnal motion A Total Lunar Eclipse Earth’s shadow at the Moon W E
