Observed Phases of the Moon

R. Rogers, Nov 29, 2011

8th

Grade Science

ButlerMiddleSchool

Full moon on Dec 10

Tonight Nov 29

Phases of the Moon as it revolves around the Earth

They always follow one another in the same order

Sun

Why does the Moon change shape?

•From day to day we view the bright part of the moon’s surface from different angles so it appears to change shape as it revolves around us

•The different shapes, called phases, depend on how much of the illuminated half of the moon faces earth

New and Full Moons

• We would expect a new moon to block sunlight from hitting the earth

• We would expect the earth to block sunlight from reaching a full moon

• However, we only see the expected once in a great while

SunLight

New

Full

Motion of Moon and Earth Orbital plane of moon is tilted 5º from earth’s orbital plane, this causes a misalignment of the earth, moon, and sun

Eclipse

• Once in awhile, the earth, moon, and sun do "line up”, this is called an eclipse

• Eclipses are rare– Roughly 4 to 7 occur in any given year, but most of

them are minor or "partial" eclipses.

• They can occur two ways– Solar Eclipse– Lunar Eclipse

Solar Eclipse – Only during a New Moon

The moon casts a shadow on the Earth, people in shadow experience a brief period of darkness during the day

Actual Solar Eclipse

Partial Total

moon

Lunar Eclipse – Only during a Full Moon

The earth casts a shadow on the full moon

Actual Lunar Eclipse• Sequence of photos showing Earth’s

shadow on the Moon

Solar Eclipse

Lunar Eclipse

Sun M E

Sun E M

Next Eclipse?