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