Flash Science
All explainers
Every article on the site, grouped by subject and newest first within each. Thirty-nine explainers so far, published one a day since 13 July 2026.
Technology & Engineering
13 explainers.
- How Does Camera Autofocus Find a Sharp Image? — See how contrast and phase detection measure blur, move lens groups and track subjects—and why blank walls, darkness and motion make autofocus fail. (2026-08-20)
- How Do Undersea Internet Cables Carry the World’s Data? — Follow Internet data through a landing station, optical fibre and powered repeaters to a deep-sea repair — and why ocean distance makes some latency unavoidable. (2026-08-19)
- How Does Password Hashing Protect Accounts? — See how salts, slow password hashes, work factors and optional peppers limit database-breach damage—and why hashing cannot stop phishing or reused passwords. (2026-08-17)
- How Does an LED Produce Light? — Follow electrons and holes through an LED, calculate photon energy, see how blue LEDs make white light, and learn why efficient lamps still get hot. (2026-08-15)
- How Does a Computer Chip Use Ones and Zeros? — See how voltage ranges, CMOS transistors, logic gates, memory and clocks turn analog physics into reliable binary computation. (2026-08-13)
- How Does Wi-Fi Work? — Wi-Fi works by encoding your data onto invisible radio waves that a router and your devices broadcast back and forth, turning bits into signals and back again. (2026-07-31)
- How Does GPS Know Where You Are? — GPS finds you by timing signals from four or more atomic-clock satellites and turning the delays into distances, all at the speed of light. (2026-07-27)
- How Does Bluetooth Work? — Bluetooth is short-range 2.4 GHz radio. Learn how pairing, frequency hopping and low-power design let your devices talk wirelessly without tangling. (2026-07-25)
- How Does a Refrigerator Keep Things Cold? — A refrigerator doesn't create cold; it pumps heat out of the food and dumps it into the room, using a refrigerant that cycles between evaporating and condensing. (2026-07-23)
- How Does a Microwave Oven Heat Food? — A microwave oven heats food by broadcasting radio waves that make water molecules jiggle billions of times a second, and that molecular motion is heat. (2026-07-21)
- How Do Noise-Cancelling Headphones Work? — Noise-cancelling headphones use tiny microphones to listen to surrounding noise, then play an opposite sound wave that collides with it and cancels it out. (2026-07-17)
- How Do Batteries Work? — A battery stores energy as chemistry, not electricity. A reaction between two materials pushes electrons through your device, turning chemical energy into power. (2026-07-15)
- How Do Airplanes Fly? — Airplanes fly because their wings push air downward and the air pushes back up. Lift balances weight, thrust overcomes drag — and the popular myths do not hold. (2026-07-13)
Earth & Environment
10 explainers.
- Why Is the Sky Blue? — The sky is blue because tiny air molecules scatter short blue wavelengths of sunlight far more than longer red ones, spreading blue light across the whole sky. (2026-08-16)
- Why Is the Ocean Salty? — The ocean is salty because acidic rain dissolves minerals from rock and rivers carry them to sea, where salt builds up to about 3.5% and stays steady. (2026-08-14)
- Why Does the Moon Cause Tides? — The Moon's gravity stretches Earth's oceans into two bulges, and as the planet spins beneath them we get two high and two low tides a day. The Sun helps too. (2026-08-12)
- Why Do We Have Seasons? — Seasons come from Earth’s ~23.4-degree axial tilt changing the angle of sunlight and length of day, not from the planet’s distance to the Sun. (2026-08-08)
- How Do Caves Form? — See how weakly acidic groundwater enlarges fractures, why stalactites arrive later, and how sulfuric acid, lava, waves and ice form other caves. (2026-08-05)
- How Do Clouds Stay in the Sky? — Cloud droplets do fall—but often only centimeters per second. See how drag, updrafts, condensation and particle growth keep a cloud visible. (2026-08-03)
- How Does a Hurricane Grow? — A hurricane grows through a fragile ocean–atmosphere feedback. Follow moisture, latent heat, pressure and rotation—and see why warm water is not enough. (2026-08-01)
- How Does a Tornado Form? — Wind shear and a supercell create rotation aloft, but tornado formation depends on near-ground vorticity, downdrafts and stretching. See what remains uncertain. (2026-07-30)
- How Does Lightning Form? — Lightning starts with charge separation among ice particles, then breakdown and leaders build a plasma path. Follow the evidence—and the limits of what is known. (2026-07-28)
- How Do Rainbows Form? — Rainbows form when sunlight enters raindrops, bends, reflects off the back and bends again, splitting white light into colours that reach your eye at a fixed angle. (2026-07-19)
Space & Astronomy
7 explainers.
- A Day on Venus Outlasts Its Year — Venus takes about 243 Earth days to rotate but only 225 days to orbit the Sun. The headline is true—depending on what ‘day’ means. (2026-08-18)
- How Do the Northern Lights Glow? — Aurora colors come from excited oxygen and nitrogen—not colored solar wind. See why altitude, atomic lifetime and camera exposure change the sky. (2026-08-11)
- Why Does the Earth Spin? — Earth spins because it inherited angular momentum from the spinning cloud it formed in 4.5 billion years ago. With almost nothing to slow it, it just keeps turning. (2026-08-10)
- Why Does the Moon Always Show the Same Face? — See why the Moon must rotate to keep one face toward Earth, how tidal torque created synchronism, and why libration reveals more. (2026-08-09)
- How Does a Black Hole Trap Light? — Learn why light still moves locally at c near a black hole, while curved spacetime removes every future-directed route from inside the event horizon. (2026-08-07)
- What Would Happen If the Earth Stopped Spinning? — If Earth stopped spinning suddenly, everything would keep moving at up to 1,600 km/h. Even a gradual stop would bring six-month days and a reshaped world. (2026-08-04)
- What Would Happen If the Sun Disappeared? — A physics thought experiment: if the Sun vanished, Earth would keep light and gravity for ~8 min 20 sec, then fly off in a straight line and slowly freeze. (2026-08-02)
Life & Chemistry
9 explainers.
- Why Do Onions Make You Cry? — Onions make you cry because cutting them releases enzymes that build a volatile tear-inducing gas. Learn the chemistry — and how to stop the tears. (2026-08-06)
- How Does Sunscreen Work? — Sunscreen works mainly by absorbing UV light and releasing it as heat, with some scattering. Learn what SPF means and how to use sunscreen correctly. (2026-07-29)
- How Do Geckos Walk on Walls? — See how lamellae, branching setae, nanoscale contact, directional shear and toe peeling give many geckos fast, reversible dry adhesion. (2026-07-26)
- How Do Fireflies Make Light? — Follow the ATP- and oxygen-dependent chemistry that creates firefly photons, then see how lantern anatomy and physiology time species-specific flashes. (2026-07-24)
- Why Do Leaves Change Color in Fall? — See how seasonal cues trigger leaf senescence, nutrient recovery, chlorophyll breakdown, yellow carotenoid exposure and species-specific red pigment production. (2026-07-22)
- How Does a Pencil Write? — A pencil line is controlled wear. Follow graphite–clay fragments from a changing point into paper’s fibers and learn what makes a mark dark. (2026-07-20)
- Why Is Ice Slippery? — Surface disorder, frictional heating, pressure, water and ice debris share the answer—and temperature, speed and contact decide which dominates. (2026-07-18)
- How Does Soap Remove Grease? — Soap’s two-sided molecules lower oil–water tension, stabilize droplets and let rinsing carry grease away. Learn why foam is not cleaning power. (2026-07-16)
- How Does Metal Rust? — Follow electrons, ions, oxygen and water through rust formation—and see how coatings, zinc and passive alloys interrupt the circuit. (2026-07-14)
Pages about the publication
- About Flash Science — who writes it, and what it does not claim to be.
- Editorial methodology — how each explainer is researched, sourced and corrected.
- How we make images — which pictures are AI illustrations and which are photographs.
- Contact the editorial desk — corrections are read first.
- Privacy policy — what is collected, and what is not.
- Terms of use
Machine-readable
- XML sitemap — every URL with its last-modified date.
- RSS feed — the twenty most recent explainers.