Moon

The correct answer is option 'A', the Moon. The Moon appears to change its shape because of its different phases.

Phases of the Moon

The Moon goes through a cycle of different phases, which are determined by its position in relation to the Earth and the Sun. These phases include the New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, and Waning Crescent.

Reason for Changing Shape

The Moon does not actually change its shape, but it appears to change its shape from our perspective on Earth. This is because the Moon does not emit its own light; it reflects the sunlight that falls on its surface. The part of the Moon that is illuminated by the Sun can be seen from Earth, while the part that is in shadow is not visible.

Interaction of the Earth, Moon, and Sun

The changing phases of the Moon are a result of the interaction between the Earth, Moon, and Sun. As the Moon orbits around the Earth, different amounts of its illuminated side are visible to us. This is because the relative positions of the Moon, Earth, and Sun change.

New Moon

During the New Moon phase, the side of the Moon that is facing the Earth is not illuminated by the Sun. As a result, the Moon appears completely dark and is not visible from Earth.

Waxing Crescent

As the Moon moves in its orbit, a small sliver of its illuminated side becomes visible from Earth. This is called the Waxing Crescent phase. The shape of the illuminated portion of the Moon appears to be a curved crescent.

First Quarter

The First Quarter phase occurs when half of the Moon's illuminated side is visible from Earth. The illuminated part is shaped like a half-circle.

Waxing Gibbous

During the Waxing Gibbous phase, more than half but less than the full illuminated side of the Moon is visible from Earth. The shape of the illuminated portion appears to be bulging on one side.

Full Moon

The Full Moon phase occurs when the entire illuminated side of the Moon is visible from Earth. The Moon appears as a complete circle during this phase.

Waning Gibbous

After the Full Moon, the illuminated portion of the Moon starts to decrease. During the Waning Gibbous phase, more than half but less than the full illuminated side is visible, and the shape appears to be bulging on the opposite side.

Third Quarter

In the Third Quarter phase, half of the illuminated side is visible, but it is shaped like a half-circle on the opposite side compared to the First Quarter phase.

Waning Crescent

The Waning Crescent phase occurs when a small sliver of the Moon's illuminated side is visible, but it appears to be a curved crescent on the opposite side compared to the Waxing Crescent phase.

Conclusion

In conclusion, the Moon appears to change its shape because of its different phases. These phases are a result of the Moon's position in relation to the Earth and the Sun, and the amount of its illuminated side that is visible from our perspective on Earth. While the Moon itself does not change its shape, the changing phases provide a visually