Phases of the Moon. Moon Phase Views For practical purposes, phases of the Moon and the percent of the Moon illuminated are independent of the location.

Phases of the Moon

Moon Phase Views

• For practical purposes, phases of the Moon and the percent of the Moon illuminated are independent of the location on the Earth from where the Moon is observed.

• That is, all the phases occur at the same time regardless of the observer's position.

Moon Phase Views

• New Moon, First Quarter, Full Moon, and Last Quarter phases are considered to be primary phases and their dates and times are published in almanacs and on calendars.

• The two crescent and two gibbous phases are intermediate phases, each of which lasts for about a week between the primary phases.

New Moon • The Moon's dark side is

facing the Earth. • The Moon is not visible

(except during a solar eclipse).

• This means that the Sun, Earth, and Moon are almost in a straight line, with the Moon in between the Sun and the Earth. 

• This happens during our daylight hours. 12 noon, to be exact!

Waxing Crescent

• The Moon appears to be partly but less than one-half illuminated by direct sunlight.

• The crescent will grow larger and larger every day, until the Moon looks like the First Quarter Moon.

First Quarter

• One-half of the Moon appears to be illuminated by direct sunlight.

• The right half of the Moon appears lighted and the left side of the Moon appears dark.

• This phase is 6 hours behind the sun. On meridian at sunset. Sets at midnight. 

Waxing Gibbous

• The Moon appears to be more than one-half but not fully illuminated by direct sunlight.

• "Waxing" means increasing, or growing larger.

Full Moon • The Moon's illuminated side is

facing the Earth and appears to be completely illuminated by direct sunlight.

• This means that the Earth, Sun, and Moon are nearly in a straight line, with the Earth in the middle. 

• This phase is 12 hours behind the sun. On the meridian at midnight, sets at sunrise. Rises at sunset.

Waning Gibbous

• The Moon appears to be more than one-half but not fully illuminated by direct sunlight.

• The amount of the Moon that we can see will grow smaller and smaller every day.

• "Waning" means decreasing, or growing smaller.

Last Quarter • One-half of the Moon

appears to be illuminated by direct sunlight.

• Sometimes called Third Quarter. 

• The left half of the Moon appears lighted, and the right side of the Moon appears dark. 

• This phase is 6 hours ahead of the sun. On the meridian at sunrise, rises at midnight and sets at noon.

Waning Crescent

• The Moon appears to be partly but less than one-half illuminated by direct sunlight.

• The crescent will grow smaller and smaller every day, until the Moon looks like the New Moon.

Moon Phases Movie

Moon Phases in Whole

Moon Visibility

• The table gives a summary of approximately when the Moon is visible and where to look (the crescent and gibbous phases are in between the table values).

• There are times during the moon's monthly cycle that the Moon is sometimes visible in broad daylight!

Moon Visibility

• There are times during the moon's monthly cycle that the Moon is sometimes visible in broad daylight!

• The lighted part of the moon always points towards the sun.

PhaseAhead or Behind the Sun

Rise Time in

East

Mid-Point In

Sky

Set Time In West

New Within few minutes Sunrise Noon Sunset

1st Qtr. 6 hrs behind Noon Sunset Midnight

Full 12 hrs behind Sunset Midnight Sunrise

3rd Qtr. 6 hrs ahead Midnight Sunrise Noon

Moon Visibility

• If lighted on the right, the sun is ahead of the moon.

• If the left portion of the moon is lighted, the moon is ahead of the sun.

Moon Phase Misconception • "The most common incorrect reason given for the cause

of the Moon's phases is that we are seeing the shadow of the Earth on the Moon!

• But this cannot be correct: when the Moon passes through the shadow of the Earth, we get a lunar eclipse.

• Anyone who has seen a lunar eclipse, though, might remember that the Moon actually passes through the Earth's shadow only rarely, so that can't be why the Moon has phases.

• The real reason for the Moon's phases depends on two things: the Moon is round, and the angle it makes with the Earth and Sun changes over its orbit.“

- As Quoted From Bad Astronomy