Phases of the Moon
The bright part of the Moon changes shape.
Look at the Moon
On some nights the Moon is a full bright circle. On other nights it is only a part of a circle, or cannot be seen.
What are these changing shapes called?
What this lesson covers
The idea
The phases of the Moon are the day-to-day changing shapes of its bright portion seen from Earth; on full Moon day (Purnima) it is a full bright circle, and on new Moon day (Amavasya) it is invisible.
Look at the Moon
On some nights the Moon is a full bright circle. On other nights it is only a part of a circle, or cannot be seen.
What are these changing shapes called?
- Phases of the Moon
- Eclipses of the Moon
- Seasons
Find two phases
Find the full Moon and the new Moon.
Phases
The day-to-day changing shapes of the bright part of the Moon, as seen from Earth, are called the phases of the Moon. On full Moon day (Purnima) we see a full bright circle. On new Moon day (Amavasya) the Moon cannot be seen.
The changing shapes of the bright part of the Moon, as seen from Earth, are its phases. Full Moon day (Purnima): full circle. New Moon day (Amavasya): not visible.
Notes
Phases are the changing shapes of the Moon's bright part. Purnima = full Moon, Amavasya = new Moon.
Check yourself
The changing shapes of the bright part of the Moon are called its …
On full Moon day, the Moon appears as …
On new Moon day, the Moon is …
Full Moon day is also called …
- seasons. Seasons are caused by the Earth's revolution.
- phases — correct. Yes!
- eclipses. Eclipses are different from phases.
- a thin crescent. A full Moon is a full bright circle.
- not visible at all. That is the new Moon.
- a full bright circle — correct. Yes!
- not visible — correct. Yes!
- a full bright circle. That is the full Moon.
- a half circle. On new Moon day it is not visible.
- Amavasya. Amavasya is the new Moon day.
- Purnima — correct. Yes!
- Uttarayan. Purnima is the full Moon day.