Mochi IsleWhy do stars twinkle?
In short: Stars are so far away that they look like tiny points of light. Their light passes through layers of moving air above us, and warm and cool pockets of air bend it slightly this way and that, so stars seem to twinkle.
How it works
Stars are huge, glowing balls of hot gas like our Sun, but they are so far away that each one shrinks to a tiny point in the sky.
Earth is wrapped in a thick blanket of air that is always moving, with warmer and cooler patches. As starlight passes through them, it is bent slightly, so its direction and brightness keep shifting. That is the twinkle we see.
Planets such as Venus and Jupiter are much closer, so their light comes from a tiny disc rather than a single point. Moving air affects them less, so planets usually do not twinkle much. Astronomers build telescopes on high mountains to look through less air.
Where to see it in New Zealand
Takapō (Lake Tekapo) is in the Aoraki Mackenzie International Dark Sky Reserve, with so few lights that the sky fills with stars. In winter, people get up before dawn to see the Pleiades star cluster, Matariki in Māori. For many iwi its rising marks the Māori New Year (some look to Puanga, Rigel, instead), now a New Zealand public holiday.
Try it together
On a clear night, go with an adult somewhere away from bright lights and look at the stars. Compare: do the stars near the horizon twinkle more than the ones overhead?
Kids also ask
Why can't we see stars in the daytime?
The stars are still there in the daytime, but sunlight makes the whole sky so bright that their faint light is drowned out.
Are all stars the same colour?
No. Look closely and you will see some stars are bluish-white and others are yellow or reddish. The colour depends on how hot a star's surface is; the hottest stars look bluish-white.
In the game, “Twinkling stars” 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 “Twinkling stars” on the island ↗ All cards in the Sky set