PHASES OF MOON
Everyday you look into the sky, you see a different moon. Isn’t it? The
It’s so because the moon is visible to us only when sunlight falls on it. Because the Moon has no light if its own. This is just like an object kept in your room, need a source of light to be seen. When there is no ,ight source in the room, that object will not be visible to you.
Thus, three things determine, what shape of moon is visible to us:
- The side visible to us (which is constant)
- The direction of sunlight
- Position of Sun, Moon and Earth, in respect to each other.
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WHAT DO WE MEAN BY "PHASES OF MOON"?
The Moon doesn’t shine by itself. What we see from Earth is sunlight reflecting off the Moon’s surface. As the Moon orbits Earth, the amount of light we see changes based on the angle between the Sun, Moon, and Earth.
These changing shapes of the moon we see each night are called “phases of the Moon”.
WHY DO PHASES OF MOON OCCUR?
The Moon takes about 29.5 days to orbit Earth once. This period is called a lunar month.
As it moves, different portions of its sunlit side face the Earth.
At times, the side facing the earth is completely lit by Sun. Then, a complete circular moon (
Full moon ) can be seen from that portion of Earth. At other side, the side which is facing earth is not receiving any sunlight. So, Moon will not be visible at all from Earth (
New Moon). Similarly, at times, different portions visible to Earth, is lit by Sun (
, etc). Thus, we have 8 different phases of Moon, visible to us.
Varying spectrum as per alignment of Sun, Moon and Earth.
PHASES OF MOON
THERE ARE 8 PHASES OF MOON:
- New Moon
- Waxing Crescent Moon
- Half Moon (First Quarter)
- Waxing Gibbous Moon
- Full Moon
- Waning Gibbous
- Half Moon (Third Quarter)
- Waning Crescent
And then the cycle repeats itself, with New Moon following the Waning Crescent Moon
PHASE 1 : NEW MOON
Position : When the Moon is between the Earth and the Sun.
Cause: The side which is seen by Earth, is not lit by Sun. The other side which is lit by Sun is not visible to us.
What we see : Moon is not visible from Earth (New Moon).
Interesting fact: This phase starts the lunar cycle. Solar eclipses happen only during New Moon.
PHASE 2 : WAXING CRESCENT MOON
Position : When the Moon is at about 45° between the Earth and the Sun.
Cause: As the Moon comes at an angle to Earth, as small part of the sunlit part on the right side of Moon can now be seen from the Earth.
What we see : Crescent (sickle shape) moon
“Waxing” means growing.
This phase is visible just after sunset.
PHASE 3 : HALF MOON (FIRST QUARTER)
Position : When the Moon is at about 90° to the Earth.
Cause: Half of the Moon faces the sunlight and this half (on the right side) is visible from the Earth, as now the Moon is just opposite to it.
What we see : Half of the Moon (Semi-circle)
Called “First Quarter” because the Moon is one-fourth through its orbit or through one- fourth of its Lunar cycle
PHASE 4 : WAXING GIBBOUS MOON
Position : The Moon moves to left, now oblique to Earth (approximately 45° to left)
Cause: Almost the whole of Moon’s surface, facing the Earth, is lit by the Sun.
What we see : An almost complete (but not complete) Moon is seen
Light continues to grow (wax). The sunlight is still falling on the right side of Moon.
PHASE 5 : FULL MOON
Position : The Moon is in line with Earth and Sun.
Cause: Whole of Moon’s surface, facing the Earth, is lit by the Sun. Thus, whole of Moon is visible to us.
What we see : Full spherical moon (Full Moon)
Lunar eclipses happen only during Full Moon.
PHASE 6 : WANING GIBBOUS
“Waning” means shrinking. (Now the lit part of Moon will continue to decrease till it is completely invisible in next phases)
Position: The Moon starts to move toward right now. It is oblique to Earth but still to left of Earth.
Cause : Most of the Moon’s surface is visible from Earth (but not complete), except for a small part of the right side of Moon. This is because the sunlight mainly falls on left side of Moon, due to its position.
What we see : An almost complete moon (Waning Gibbous Moon)
PHASE 7 : HALF MOON (THIRD QUARTER/ LAST QUARTER)
Position: The Moon is again at 90° to Earth.
Cause : The Moon’s left surface is visible from Earth. And thus, once again half of the Moon is visible from Earth (but this time, the left side).
What we see : Half Moon (semicircle)
The Moon has crossed three- fourth of its orbit. Therefore, it’s also called 3rd Quarter Moon/ Last Quarter Moon
PHASE 8 : WANING CRESCENT
Position: The Moon travels to right and stays oblique to Earth. Now. it has come to right to earth.
Cause : Only a crescent shaped sunlit area of Moon (on left side of Moon) is visible from earth.
What we see : Crescent shaped moon (Waning Crescent Moon)
🧠 IMPORTANT POINTS AND SUMMARY
IMPORTANT WORDS TO KEEP IN MIND :
Waxing : Moon is getting bigger
Waning : Moon is getting smaller
Crescent : Less than half of Moon is visible
Gibbous : More than half of Moon is visible
TIPS:
Light on Right = Waxing (Tip : “when it is “right”, Moon grows!)
Light on Left = Waning (Tip : “when it is “left” behind, Moon starts shrinking, as it is sad!)
📚 FUN FACTS
🌊 The Moon affects ocean tides due to gravity.
🌝 Some people believe Full Moons affect sleep or behavior (not scientifically proven).
🌚 You can sometimes see the moon during the day, depending on its position.
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