Supermoon: how an illusion makes the full Moon appear bigger than it really is

Every few months, we have a special sighting of the Moon where it is not only a full Moon but what is known as a supermoon.

To understand why it is a supermoon, we first have to understand why different parts of the Moon are lit up at other times of the months.

We see different parts of the Moon light up at different times of the month. This is because the Moon is at different positions in its orbit around Earth relative to the Sun.

• A full Moon is when the Moon, Earth and Sun are lined up. The sunlight shines on the whole lunar surface and is reflected back to Earth.
• A New Moon. When the Moon is between Earth and the Sun, no sunlight can reflect off its surface.
• The Moon orbit around the Earth is an ellipse. The Moon is sometimes closer to the Earth than at other times. When it is closest to Earth and a Full Moon, it is called a supermoon.