Why Is the Sky Blue — and Why Does It Turn Orange at Sunset?
Sunlight looks white, but it is really every colour mixed together. What happens next is the reason the sky changes colour twice a day.
Knowledge Hub
Browse by subject
Why does that happen?
ExploreMeet the neighbours
ExploreNews from everywhere
ExploreNews from home
ExploreLooking after the Earth
ExploreFootprints from the past
ExploreGames, records, heroes
ExploreInventions and ideas
ExploreFacts worth keeping
ExploreEverything
Newest first. Every article shows its reading time and, where it has been set, the age band it is written for.
Sunlight looks white, but it is really every colour mixed together. What happens next is the reason the sky changes colour twice a day.
A bee that finds flowers comes home and dances. The angle and the length of the dance tell the hive exactly where to fly.
Most Moon landings aimed for the easy middle. India aimed for the hardest, coldest, most interesting edge — and there was a good reason.
Older than the Himalayas, and home to frogs, birds and plants that live in these hills and absolutely nowhere else on Earth.
For most of history, counting had no way to write 'none'. The idea that fixed it came from India — and it made modern mathematics possible.
Your immune system learns from experience. A vaccine is a way of giving it the lesson without the illness.
It is not a season that simply arrives. The monsoon is the sea and the land swapping roles — and it comes down to how quickly each one heats up.
They are falling — constantly. The trick is that they are also moving sideways fast enough to keep missing the Earth.
The yellows and oranges were in the leaf the whole time. Autumn just takes away the thing that was covering them up.
One of India's most endangered birds is a poor pilot with excellent eyesight — pointed the wrong way. Conservationists found a fix.
Humans have spoken for a very long time and read for a very short one. Learning to read rewires a part of the brain meant for something else.
Athletes have very different bodies and very different impairments. Classification is the quiet system that decides who competes against whom.
Recycling is not magic and it is not pointless. It is a sorting problem — and how you throw things away decides whether it works.
Anyone can put anything on a screen. Here is the short checklist that professional fact-checkers actually use.
Being kind is not something you either are or aren't. It is a set of things you can practise — starting with noticing.