Mochi IsleWhy does the evening sky turn red and orange?
In short: In the evening the sun is low, so its light travels through much more air to reach us than at midday. Most of the blue is scattered away on the way, leaving mostly red and orange light.
How it works
At midday the sun is high, so its light crosses only a thin layer of air. In the evening the sun sits near the horizon, and its light takes a long, slanting path through ten or more times as much air, and dozens of times more right at the horizon.
Air scatters blue light in every direction. The longer the path, the more blue gets scattered away, so the light that finally reaches your eyes is mostly the red and orange that scatter less.
Clouds lit by this red and orange light become a glowing sunset. When the air holds dust, moisture or smoke, the colours are sometimes even stronger.
Where to see it in New Zealand
Beaches on New Zealand's west coast are great places to watch the sun sink into the Tasman Sea. Sunrise works the same way, so the early-morning sky is often orange and red too.
Try it together
On a clear evening, go with an adult to an open place where you can see the western sky. Compare the colours just before sunset with the colours at midday. Do not look straight at the sun.
Kids also ask
Why does the setting sun look bigger?
Mostly it is an illusion. Near the horizon, your brain compares the sun with houses, trees and hills, so it seems bigger. If you photograph it and measure, its size has barely changed.
Is a red sunrise caused by the same thing?
Yes. At sunrise the sun is low too, so its light also crosses a lot of air, and the morning sky is often red and orange.
In the game, “Sunset glow” 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 “Sunset glow” on the island ↗ All cards in the Sky set