Topic

The science of everyday life

The physics and biology hiding in plain sight: why the sky and sea and your blood are the colours they are, the science in the air and water around you, the body myths everyone repeats, and the quiet things your body does on its own.

why the world looks the way it does

The colour of things

Nature

Why is the sky blue?

Sunlight is white, a mix of every colour. As it passes through the air, molecules of nitrogen and oxygen scatter the short,…

✓ fact-checked

Nature

Why is the sea blue?

Water is intrinsically blue. It gently absorbs red and orange light through the vibration of its own molecules, so once you…

✓ fact-checked

Nature

Why is blood red?

Blood is red because of haemoglobin, the oxygen-carrying protein packed inside red blood cells. Its haem group holds an iron…

✓ fact-checked

Nature

Why do leaves change colour in autumn?

A tree stops making chlorophyll and pulls the valuable bits (nitrogen and magnesium) back out of the leaf before dropping it.…

✓ fact-checked

the science overhead and underfoot

Water, air and sky

Nature

Why is the ocean salty?

The sea is salty because rain slowly dissolves the rock on land, and rivers carry those dissolved salts to the ocean. Water…

✓ fact-checked

Nature

Why can you smell rain coming?

You are smelling two different things. The earthy scent after rain is petrichor, driven by geosmin, a molecule made by soil…

✓ fact-checked

Nature

Why do meteor showers happen every year?

Because Earth's orbit crosses the same streams of comet debris at the same point every year. A comet lays down a long trail…

✓ fact-checked

Nature

Why do animals go quiet in an eclipse?

Because the sudden darkness of totality looks exactly like nightfall, and most animals run their daily schedule off light,…

✓ fact-checked

things everyone says that aren't true

Body myths, busted

The Body

Do you lose most of your body heat through your head?

No. Your head is only about 7 to 10% of your body's surface area, and it loses heat roughly in proportion to that, so you…

✓ fact-checked

The Body

Do you swallow spiders in your sleep?

No. The famous claim that the average person swallows four to eight spiders a year in their sleep is completely made up, with…

✓ fact-checked

The Body

Does cracking your knuckles cause arthritis?

No. Cracking your knuckles does not cause arthritis. Multiple studies, including controlled research on hundreds of people,…

✓ fact-checked

The Body

Does shaving make hair grow back thicker?

No. Shaving does not make hair grow back thicker, darker, coarser or faster. A razor only cuts the dead hair shaft at the…

✓ fact-checked

quirks your body runs without you

The body on autopilot

The Body

Why do you get pins and needles?

Pins and needles come from a squashed nerve. Sitting on a limb both crushes the nerve and cuts off its own tiny blood supply,…

✓ fact-checked

The Body

Why do you get a stitch when you run?

The stitch, properly called exercise-related transient abdominal pain, is a real and common phenomenon whose cause is still…

✓ fact-checked

The Body

Why do you get a second wind?

A second wind is the shift from early breathlessness to comfortable rhythm a few minutes into exercise. The most solid…

✓ fact-checked

The Body

Why does only one nostril work at a time?

Because of the nasal cycle: spongy, blood-filled tissue in your nose swells on one side and shrinks on the other, so one…

✓ fact-checked