4. The Moon continues to wax. As soon as more than half of the disc is illuminated, its shape is referred to as gibbous. The gibbous moon appears to grow each night until we see the full sunlit face of the Moon.
5. When the Moon is on the far side of the Earth, the side of the Moon we see is totally lit up. This is known as a full moon.
6. During the second half of the lunar month, the Moon grows thinner each night. This is called waning. Its shape is still gibbous at this point, but grows a little thinner each night.
7. As it approaches a new moon again, the Moon is a waning quarter.
8. The crescentwanes until we can again see none of the lit part of the Moon and the phase starts again with a new moon. The phases of the Moon are usually included on calendars.
Eclipses An eclipse happens when the light of the Sun is blocked by the Moon or the Earth.
A solar eclipse happens when the Moon comes between the Sun and the Earth and causes a shadow to fall on the Earth’s surface. At the time of total eclipse, only the flames of the outer edge of the Sun can be seen.
z Fig. 23.2.4
How a solar eclipse happens
Sun Penumbra Moon Umbra Earth F A ‘blue’ moon
happens when there are two full moons in one calendar month. It happens about once every three years.
Penumbra A lunar eclipse happens when the Earth’s shadow falls on the Moon. Sun Earth Moon Penumbra Umbra Penumbra z 406 Fig. 23.2.5
