ScienceHow does photosynthesis work? Energy, carbon and oxygen explained
Follow photosynthesis from absorbed light to carbohydrates. Learn where the carbon and released oxygen come from, and what the familiar equation leaves out.
Science facts.
A closer look.
Clear explanations for extraordinary everyday processes. Start with a question below, then follow the evidence and further reading.
Science
ScienceWhy is the sky blue and the sunset red? A light-path explanation
Understand how air scatters sunlight, why sunsets change colour, and how the blue sky differs from blue seawater and glowing auroras.
ScienceWhy do you see lightning before you hear thunder?
Light reaches your eyes almost instantly, while thunder travels through air at about the speed of sound. The delay reveals the storm’s distance.
ScienceWhy does ice float on liquid water?
Water expands as it freezes because hydrogen bonds arrange molecules into an open crystal structure. The solid becomes less dense than the liquid beneath it.
ScienceWhy are human fingerprints different?
Finger ridge patterns form before birth through genetics and tiny differences in the womb. Even identical twins develop distinct details.
ScienceWhy does popcorn pop?
A kernel contains a small amount of water sealed inside a hard shell. Heating turns that water into steam until pressure ruptures the hull and expands the starch.
ScienceWhy do onions make you cry?
Cutting an onion breaks cells and lets enzymes create a volatile irritant. It reaches the eye, dissolves in tears and triggers a protective reflex.
ScienceWhy does metal feel colder than wood?
At the same room temperature, metal draws heat from your hand faster than wood because it conducts heat far more efficiently. The sensation measures heat flow, not temperature alone.
ScienceWhy do bridges have expansion gaps?
Steel and concrete expand when heated and contract when cooled. Expansion joints give the structure room to move without buckling or cracking.
ScienceWhy do echoes repeat your voice?
Sound reflects from hard, distant surfaces. A distinct echo occurs when the reflected sound arrives late enough for your brain to separate it from the original.
ScienceHow does GPS know where you are?
GPS receivers compare precise time signals from several satellites. The differences reveal distances, and geometry converts those distances into a position on Earth.
ScienceHow does a rainbow form?
Raindrops separate sunlight into colours through refraction, internal reflection and dispersion. The bow’s position depends on the Sun behind you and droplets in front.
ScienceWhy do magnets attract iron?
Magnetic fields interact with the electrons in iron. In a magnet, many tiny magnetic regions align; nearby iron regions can align temporarily, creating attraction.
ScienceWhy does baking soda fizz with vinegar?
An acid-base reaction produces carbon dioxide gas. The bubbles are the gas escaping from solution, while water and a salt remain in the mixture.
ScienceWhy does bread rise?
Yeast converts sugars into carbon dioxide and alcohol. Gluten traps the gas in elastic pockets, then heat expands and sets the loaf’s structure.
ScienceWhy are soap bubbles round?
Surface tension pulls a thin liquid film toward the smallest surface area that encloses its air. A sphere is the most economical shape for a given volume.
ScienceWhy does salt melt ice on roads?
Salt lowers water’s freezing point. A salty film can remain liquid below 0°C, but the effect weakens in extreme cold and depends on concentration and contact.
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