Mochi IsleWhy does the Moon change shape?
In short: The Moon makes no light of its own; we see the side lit by the Sun. As the Moon circles Earth, its phases repeat about every 29.5 days, and we see more or less of the lit side, from crescent to full moon and back.
How it works
The Moon is a ball with one half always lit by the Sun and the other half dark. As it travels around Earth, the angle we see it from keeps changing.
When the Moon is between the Sun and Earth, its lit side faces away from us and we can hardly see it. This is the new moon. When it is on the far side of Earth, the whole lit side faces us: a full moon. In between, we see a crescent, a half moon or a bulging (gibbous) moon.
Many people think the Moon's shape changes because Earth's shadow covers it, but that is not true. Earth's shadow only falls on the Moon during a lunar eclipse, and those do not happen every month.
Where to see it in New Zealand
New Zealand is in the Southern Hemisphere, so the Moon looks flipped compared with the north: there it starts lighting up on the right; here it lights up from the left. The Māori lunar calendar, the maramataka, uses the Moon's phases to guide fishing and planting.
Try it together
For one or two weeks, look for the Moon each day (sometimes you will need to look a little earlier or later) and draw its shape with an adult. Watch how it changes from day to day.
Kids also ask
Why can you sometimes see the Moon in the daytime?
The Moon is lit brightly by the Sun, so you can often see it when the daytime sky is not too bright, especially around the days of a half moon.
Does the same side of the Moon always face us?
Yes. The Moon takes the same time to spin once as it does to travel once around Earth, so we always see the same side.
In the game, “Moon phases” is a nature card from the Sky set, and it can turn up on any island.
Your child finds this card by reaching the right place or meeting the right weather on the island, and lights it up by answering the question on the back. Tap the button below and the game shows your child which island it is on and how to find it. Mochi Isle is a browser learning game for ages 5 to 18; the main island and the daily lesson are free.
Find “Moon phases” on the island ↗ All cards in the Sky set