Topic
Light and color questions for kids
Here are 222 questions about light, color and seeing from 18 A Million Whys books, each with a short video answer. Book 13, The Light Expedition is all about light, color and seeing, and the rest come from other books in the series. Tap any question to watch the video and read the answer.
From Book 13: The Light Expedition (150)
Why Does Light Travel in Straight Lines?
Light travels in straight lines unless something bends it, bounces it, or blocks it. That is why a flashlight beam looks like a stick of light.
Why Is Light the Fastest Thing There Is?
Light zooms along at about 300,000 kilometers every second! In one second, it could circle Earth more than 7 times.
Why Does Sunshine Take About Eight Minutes to Reach Earth?
The Sun is about 150 million kilometers away from Earth. Even light needs about 8 minutes and 20 seconds to make that trip.
Why Can You See a Sunbeam Streaming Through Dusty Air?
Light itself is invisible as it flies through clean air. You see a sunbeam only when dust, smoke, or tiny water droplets bounce some light toward your eyes.
Why Are the Spots of Sunlight Under a Tree Round?
Tiny gaps between leaves work like pinholes. Each gap makes a little picture of the Sun on the ground.
Why Can a Shadow Look Sharp One Minute and Fuzzy the Next?
A shadow is sharpest when the light is a tiny source and the object is close to the surface. When the light is bigger, or the object is farther away, the edge turns soft and fuzzy.
Why Do You Get More than One Shadow Under Several Lamps?
Every lamp is a separate source of light, and each one throws its own shadow behind your body. So several lamps make several shadows!
Why Are Shadows on Snow Sometimes Blue?
Shaded snow looks blue because it is lit by the blue sky instead of direct sunshine. The sky scatters blue light in every direction, and that light fills the shadow.
Why Can a Flashlight and Your Hands Make a Shadow Animal?
A shadow forms where something blocks light. Your hands are the object, and the wall catches the shape.
Why Does a Glass of Water Throw a Bright, Wiggly Shadow?
A clear glass of water is not invisible to light. Its curved sides bend the light, and the water focuses some of it into bright lines and patches.
Why Is It Cooler in the Shade than in the Sun?
Shade blocks the direct beams of the Sun. The heat energy in sunlight cannot warm you or the ground there.
Why Do Dark Clothes Feel Hotter in the Sun than Light Ones?
Dark colors soak up most of the light that hits them. They turn that light energy into heat.
Why Does Sunshine Feel Warm on Your Face Even When the Air Is Cold?
Sunshine warms your skin because light carries energy. Your skin absorbs some of that energy as heat.
Why Can a Cardboard Solar Oven Cook with Only Sunshine?
A solar oven uses mirrors or shiny foil to bounce extra sunlight onto a dark pan, and the box traps the warm air inside. That lets a cardboard box cook with only sunshine!
Why Does Snow Melt First Around a Dark Rock?
Dark rocks soak up more of the Sun's light than bright snow does. They turn it into heat and melt the snow right next to them.
Why Do Houseplants Lean Toward a Window?
Plants turn toward light because they use it to make food. A growth chemical in the stem moves to the shaded side, and the shaded cells grow longer.
Why Does the Bright Patch From a Window Slide Across the Floor?
The Earth is spinning, so the Sun seems to move across the sky. The angle of the light through your window changes, and the bright patch slides across the floor.
Why Is a Cloudy Day Outside Still Brighter than a Lit Room Inside?
The Sun is so powerful that even through thick clouds, daylight is much stronger than room lights. Outdoors on a cloudy day, the light can be 10 to 100 times brighter than a lamp indoors!
Why Do Shadows Disappear on Cloudy Days?
Direct sunlight comes from one small, bright spot, so it makes sharp shadows. Clouds spread the sunlight across the whole sky.
Why Does Your Shadow Stretch, Shrink, and Stretch Again as You Walk Past a Streetlamp?
A streetlamp is one small light, and your shadow always points away from it. When you are far from the lamp, your shadow is long.
Why Does Your Hand Make a Giant Shadow When It Is Close to a Lamp?
A lamp spreads its light out in all directions, like rays from a single point. If your hand is close to the lamp, it blocks a wide cone of light.
Why Can You See the Shadow of a Cloud Sliding Across a Field?
A cloud blocks sunlight and casts a shadow on the ground below it. The wind pushes the cloud along, so its shadow glides across the field.
Why Does Your Shadow Always Follow You?
Your shadow is simply the place where your body blocks light. As you move, the blocked area moves with you.
Why Do Beams of Sunlight Fan Out From Behind a Cloud?
Gaps in a cloud let sunlight shine through in beams. The beams look like they fan out from the cloud, but they are really parallel.
Why Do Tall Buildings Leave Long, Cool Shadows on City Streets?
Tall buildings block the Sun, so their shadows fall across the street and make it cooler there. In winter, when the Sun is low, the shadows are especially long.
Why Do Red, Green, and Blue Lights Mix to Make White Light?
Colored light mixes by adding. When red, green, and blue lights shine on the same spot, your eyes get all three signals at once.
Why Do Paints Mix Differently From Colored Lights?
Paint and light follow opposite rules. Paint mixes by taking colors away, but light mixes by adding colors together.
Why Can You Make Almost Any Color From Just Three Paints?
Painters can mix a huge range of colors from just a few paints. School sets often start with red, yellow, and blue, and printers use cyan, magenta, and yellow.
Why Does Mixing All Your Paints Make a Muddy Brown?
Every paint soaks up some colors of light. When you mix lots of paints, the mixture soaks up almost every color.
Why Does a Red Cellophane Sheet Change What You See?
Red cellophane lets red light pass through and blocks most other colors. That changes which light reaches your eyes, so everything looks different through it!
Why Do Colors Look Different Under Different Lamps?
Different lamps give off different mixes of colors. A warm yellow bulb makes a lot of red and yellow light but little blue.
Why Do Some People See Some Colors Differently?
Your eyes have three kinds of color-sensing cells called cones. Not everyone's cones work in exactly the same way.
Why Do Screens Use Only Red, Green, and Blue Dots?
A screen is covered in tiny dots, called pixels, that shine red, green, or blue. Your eyes blend the three lights together.
How Does the Color of Paper Change How Much Light Bounces Back?
White paper reflects almost all colors of light, so it looks white. Black paper soaks up almost all colors, so very little light comes back to your eyes.
Why Do Two Colored Flashlights Make Colored Shadows?
Each colored light casts its own shadow, and the other light lights it up. If a red light and a green light shine on an object, the spot blocked from red is lit only by green.
Why Does a Spinning Color Wheel Turn White?
Your eyes cannot keep up with colors flashing past very quickly. On a spinning wheel with all the rainbow colors, your eye blends them together.
Why Does the Same Gray Look Lighter or Darker on Different Backgrounds?
Your brain decides how light or dark something looks by comparing it with the things around it. A gray square looks lighter on a dark background and darker on a light one.
Why Do Secret Decoder Windows Reveal Hidden Messages?
A decoder window is a sheet of red plastic. It lets red light through, so red scribbles seem to vanish into the paper.
Why Does Adding White Paint Make a Color Lighter?
White paint reflects almost all light. Adding it to a color means more light bounces back, so the color looks paler and lighter.
Why Does Wet Sand Look Darker than Dry Sand?
Dry sand scatters light off every grain, so it looks pale. Wet sand has a thin film of water around each grain.
Why Do Colors on a Phone Screen Look Different From Colors on Paper?
A screen makes its own light, using tiny red, green, and blue dots. Paper only reflects the light of the room.
Why Are Roofs in Hot Places Often Painted White?
White roofs reflect most of the Sun's light instead of soaking it up. Dark roofs absorb sunlight as heat.
Why Do Old Posters in Sunny Windows Fade to Blue?
Sunlight, especially ultraviolet light, slowly breaks apart the molecules that give inks and dyes their colors. Some dyes break down faster than others.
Why Do Magicians Hang Black Cloth Behind Their Tricks?
Black velvet soaks up almost all the light that hits it. It reflects very little back to your eyes, so it looks like empty darkness.
Why Can’t You Make Black by Mixing Colored Lights?
When you mix colored lights, every new light adds more brightness. So the mix gets lighter, not darker.
Why Do Newspaper Pictures Turn Into Tiny Dots Under a Magnifier?
Newspaper photos are printed with tiny dots of ink in different sizes. From far away, your eyes blend the dots into smooth shades.
Why Can Bees See Patterns on Flowers That We Cannot?
Bees and many other insects can see ultraviolet light, which humans cannot. Many flowers have patterns that only show up in ultraviolet.
Why Does a Red Apple Look Almost Black Under a Green Light?
A red apple looks red because it reflects red light and absorbs the rest. A green light has no red in it, so there is nothing for the apple to reflect.
Why Do Artists Use a Color Wheel to Pick Colors That Look Good Together?
A color wheel arranges colors in a circle. Neighbors blend smoothly and opposites sit across from each other.
Why Does Paint Change Color a Little as It Dries?
Wet paint is a mix of tiny pigment bits floating in liquid. As the water evaporates, the paint layer changes how light moves through it.
Why Can You See Yourself in a Mirror but Not in a Wall?
A mirror is so smooth that light bounces off it in an orderly way, which makes a clear picture of you. A wall looks smooth, but up close it is full of tiny bumps.
Why Does Light Bounce Off a Mirror at the Same Angle It Hits?
Light bounces off a mirror at the same angle it came in, just like a ball bouncing off a wall. Scientists call this the law of reflection.
Why Can a Periscope Let You See Over a Wall?
A periscope uses two mirrors set at a slant to pass light around an obstacle. Light from the scene goes down the tube and into your eye.
Why Do Two Mirrors Facing Each Other Show Endless Copies?
Two mirrors facing each other show endless copies because each mirror reflects the other again and again. The copies line up like a tunnel, each one smaller than the last.
Why Does Your Face Look Upside Down in the Back of a Spoon?
A spoon is curved like a tiny mirror. The cupped inside bends light so that a face far away looks upside down.
Why Do Car Side Mirrors Say Objects Are Closer than They Appear?
Some car side mirrors curve outward, which gives drivers a wider view of the road. But a curved mirror makes everything in it look smaller.
Why Does a Makeup Mirror Make Your Face Look Bigger?
A makeup or shaving mirror curves inward, like the inside of a spoon. When your face is close, the curve spreads out the reflection into a big, upright picture.
Why Does a Swimming Pool Look Shallower than It Really Is?
Light bends when it leaves water and enters the air. Your brain assumes light always travels in a straight line, so it places the bottom of the pool higher than it really is.
Why Does a Coin Appear When You Pour Water Into a Bowl?
A coin in an empty bowl can hide behind the rim. Pour in water, and light from the coin bends as it leaves the water.
Why Does a Glass of Water Flip an Arrow Upside Down?
A tall glass of water is curved like a lens, so it bends the light passing through it. At the right distance, the picture flips from side to side.
Why Does a Magnifying Glass Make Things Look Bigger?
A magnifying glass is a lens that is thicker in the middle than at the edges. It bends the light from a small thing so the picture spreads wider across your eye.
Why Should You Never Play with a Magnifying Glass in the Sun?
A magnifying glass can gather sunlight into one small, very bright, very hot spot. That spot can scorch paper, leaves, and skin, and it can even start a fire.
Why Do Some Lenses Make Things Look Smaller?
A lens that is thinner in the middle than at the edges spreads light out. That makes things look smaller.
Why Can a Water Drop on a Leaf Work Like a Tiny Lens?
A small drop of water has a smooth, curved top. That shape bends light just like a tiny magnifying lens.
How Does a Microscope Show Things Too Small to See?
A microscope uses two lenses, one close to the object and one near your eye. Together they magnify the picture in two steps.
Why Is the Word Ambulance Written Backward on the Front of the Van?
A mirror flips writing from left to right. AMBULANCE is printed backward on the front of the van.
Why Can You See Your Room Reflected in a Window at Night?
Window glass lets most light through, but it also reflects a little, like a very faint mirror. In the daytime, the light from outside is much stronger than the reflection.
Why Can Some Windows Look Like Mirrors From the Outside in the Daytime?
Mirror-like windows have a thin metal coating that reflects some light and lets some through. Outside on a bright day, the reflection of the sky is brighter than the dim light coming from inside.
Why Does a Calm Lake Show a Mirror Picture and a Windy Lake Does Not?
Still water is flat, so it reflects light in an orderly way and makes a clear, upside-down picture. Wind and ripples tilt the surface into many little slopes.
Why Do Things Look Bigger and Closer Underwater?
Light bends when it goes from water to air. A diving mask keeps a pocket of air in front of your eyes, so light bends as it enters the mask.
Why Does a Lens Bring Light Together at One Spot?
A lens is curved so that rays of light passing through it bend toward each other. Rays from a faraway scene all meet at one place, called the focus.
Why Does a Kaleidoscope Make Endless Patterns?
A kaleidoscope has two or three mirrors set at an angle inside a tube. Bits of colored glass tumble at one end, and the mirrors reflect them again and again.
Why Do Funhouse Mirrors Make You Look Wide or Skinny?
Funhouse mirrors are curved and bumpy, so each part bends the reflection differently. A bump pushing outward makes you look skinnier there.
Why Do You Only Need a Half-Length Mirror to See Your Whole Body?
To see your whole body, a mirror only needs to be half as tall as you are. That is true no matter how far away you stand.
Why Do Shiny Round Balls Show the Whole Room in a Tiny Picture?
A shiny curved ball acts like a convex mirror that reflects light from nearly every direction. In its small surface you can see a tiny, squished picture of the whole room.
Why Can You See Through Glass but Not Through Wood?
Light passes through glass because the atoms in glass do not soak up visible light. Wood soaks up or scatters nearly all the light that hits it, so none gets through.
Why Does Frosted Glass Hide Shapes but Still Let Light In?
Frosted glass has a rough surface covered in tiny bumps. Light still gets through, but each bump bends it in a different direction, so the picture gets scrambled.
Why Does a Sheet of Paper Glow When You Hold a Flashlight Behind It?
Paper is made of tiny fibers with air gaps between them. Light going in bounces around among the fibers and spreads out, and some of it comes out the other side.
Why Does Wet Paper Turn See-Through?
Dry paper scatters light at every air gap between its fibers. Water or oil fills those gaps and bends light less, so more light slips straight through.
Why Are Some Things Shiny and Others Dull?
Smooth surfaces reflect light in one direction, so you see a bright, glossy shine. Rough surfaces scatter light in all directions, so they look dull or matte.
Why Are Metals So Shiny?
Metals contain lots of electrons that are free to move around. When light hits metal, these electrons shake and send most of the light right back out.
Why Does Polishing Make a Spoon Shinier?
Rubbing a spoon smooths out tiny scratches and bumps. A smoother surface reflects light in an orderly way, so it shines.
Why Do Air Bubbles in Water Look Silvery?
Air bubbles in water look silvery because light inside the water hits the bubble's edge at a steep angle. Instead of passing out, it bounces back.
Why Does Frost Sparkle?
Frost and fresh snow are made of tiny ice crystals with flat, shiny faces. Each face works like a little mirror.
Why Do Gemstones Sparkle More When They Are Cut?
A gemstone is cut with flat surfaces called facets. Light enters the top, bounces from facet to facet inside the stone, and exits the top again.
Why Do Glitter and Sequins Flash When You Move?
Glitter and sequins are made of lots of tiny flat, shiny pieces. They all point in slightly different directions.
Why Do CDs and DVDs Shimmer with Colors?
A CD or DVD has a spiral track of super-tiny grooves, spaced very close together. These grooves split white light into its colors.
Why Does the Inside of a Seashell Shimmer with Colors?
The inside of many shells, called mother-of-pearl, is built from lots of super-thin layers of a chalky material. Light bounces off the top and bottom of each layer, and some colors line up and grow brighter.
Why Does a Wet Leaf Look Shinier than a Dry One?
A dry leaf has tiny bumps that scatter light, so it looks dull. Water fills in the bumps and makes a smooth, clear layer on top.
Why Does Glare Make a Shiny Page Hard to Read?
A glossy page acts like a mirror and bounces the lamp's light straight toward your eyes. That bright reflection, called glare, is stronger than the light from the ink.
Why Do Phone Screens Turn Into Mirrors in Bright Sunshine?
A phone screen makes its own light, but the glass also reflects light from the sky or a window. Outdoors in sunshine, the reflected light can be brighter than the light from the screen.
Why Can a Pond Look Like a Mirror When You Look From Low Down?
When you look at water from low down, at a shallow angle, almost all of the light bounces off the surface like from a mirror. When you look from high above, more light passes through the water.
Why Is Muddy Water Cloudy?
Muddy water is full of tiny bits of dirt that float around. Each bit bounces some of the light in a new direction, so light gets scattered before it can travel far.
Why Does Milk Look White When Water Is Clear?
Milk is mostly water with tiny droplets of fat and bits of protein floating in it. These specks bounce every color of light in every direction.
Why Is the Foam on a Dark Drink White?
Foam is made of many tiny bubbles, each with a very thin skin of liquid. Light bounces off all those skins in every direction, and none of it gets absorbed before it comes back out.
Why Is Table Salt White When One Crystal Is Clear?
A single grain of salt is a tiny clear crystal. But a pile of grains has lots of surfaces that bounce light in every direction.
Why Are Some Plastics Clear and Others Cloudy?
Clear plastics have molecules arranged so that light can pass through without much scattering. Cloudy plastics have tiny crystals or added particles that bounce light around.
Why Do Some Windows Have a Thin, Shiny Coating?
Some windows have a coating that is thinner than a hair. It lets visible light pass through but reflects heat rays.
Why Does Crinkled Foil Sparkle in Every Direction?
Smooth foil acts like a mirror, sending light in one direction. Crinkled foil has lots of tiny flat patches, all pointing in different directions.
Why Do Very Dark Materials Like Velvet Seem to Swallow Light?
Black velvet is made of tiny upright fibers. Light that enters gets trapped between them and bounces around until it is absorbed.
Why Does a Laser Pointer Make a Tiny Dot Instead of a Wide Beam?
A laser pointer makes a tiny dot because its light is very organized! All of it is one color and travels together in the same direction, unlike a flashlight's wide cone.
Why Must You Never Shine a Laser Pointer at Anyone's Eyes, a Plane, or an Animal?
A laser pointer packs lots of light into a tiny spot, so it is a tool and not a toy! Never shine one at eyes, planes, or animals.
Why Does a Projector Turn a Tiny Picture Into a Huge One?
A projector turns a tiny picture into a huge one by shining light through it! A lens spreads the light across a big screen and keeps the picture sharp.
Why Does a Flip Book Make Pictures Move?
A flip book makes pictures move because your brain fills in the gaps! Each page is a little different, and your eyes hold on to each picture for a moment.
Why Do Hologram Stickers Change as You Tilt Them?
A hologram sticker changes as you tilt it because of super-tiny ridges! The ridges bend different colors of light in different directions.
How Do Optical Fibers Trap Light Inside a Thread?
An optical fiber is a thin thread of glass or clear plastic that traps light inside! The light bounces along the inside wall, again and again.
What Is Infrared Light, and Why Can We Feel It but Not See It?
Infrared light has waves a little longer than red light, so our eyes cannot see it! But warm things give it off, and we feel it as heat.
Why Do Streetlights Switch on by Themselves at Dusk?
A streetlight switches on by itself because it has a small light sensor! In daylight, the sensor keeps the lamp off.
How Does a Solar-Powered Calculator Work Without a Battery?
A solar calculator works without a battery because it makes electricity from light! A solar cell gives off a tiny bit of electricity when light hits it.
Why Can One Tiny LED Shine Red, Green, or Blue?
An LED is a tiny chip that glows when electricity flows through it! The chemicals inside the chip decide the color of the glow.
Why Does a Flashlight Beam Get Wider the Farther It Goes?
A flashlight beam gets wider the farther it goes because light spreads out! The same light covers a bigger and bigger circle.
Why Does a Flashlight Have a Shiny Cup Behind the Bulb?
A flashlight has a shiny cup behind the bulb to catch light that goes backward! The curved cup bounces it forward.
Why Does a Mirror Ball Scatter Dots of Light Around a Room?
A mirror ball is covered in lots of tiny flat mirrors, all tilted a little differently! Each mirror sends a small spot of light somewhere else.
Why Do 3-D Glasses Make Pictures Seem to Pop Out?
3-D glasses make pictures pop out because your two eyes see slightly different views! The glasses make sure each eye sees only its own picture.
Why Do Some Screens Go Dark When You Tilt Polarized Glasses?
Polarized lenses only let through light that wiggles in one direction! Many screens already give off light that wiggles one way.
Why Do Magicians' Mirror Tricks Fool Our Eyes?
Magicians' mirror tricks fool our eyes because we expect reflections to show what is straight behind the mirror! A slanted mirror can show a side wall instead.
Why Does the Same Line Look Longer with Arrowheads on the Ends?
Two lines of the same length can look different if you put arrowheads on the ends! This is the Müller-Lyer illusion.
Why Can a Laser Measure How Far Away a Wall Is?
A laser measuring tool finds a distance by timing a flash of light! The flash bounces off the wall and comes back, and a clock inside measures how long the trip took.
Why Can a Scanner Copy a Picture Using a Moving Line of Light?
A scanner copies a picture by sliding a bright bar of light across it! Tiny sensors measure how much light bounces back from each spot.
Why Do Indoor Plant Lamps Often Look Pink or Purple?
Indoor plant lamps often look pink or purple because they use red and blue light! Plants use those colors the most.
Why Do Some Solar Power Plants Use Hundreds of Mirrors?
Some solar power plants use hundreds of mirrors to gather sunlight! The mirrors tilt to follow the Sun and aim at one spot on a tower.
Why Does a Lamp Look Dimmer the Farther Away It Is?
A lamp looks dimmer the farther away it is because its light spreads out! Farther away, the light is thinner.
Why Can a Laser Read the Tiny Bumps on a Disc?
A disc has a long track of tiny pits and flat spots, and a laser inside the player reads it. A sensor notices how the laser light bounces back, and those patterns turn into sound or pictures.
Why Do Neon Signs Glow?
A neon sign is a glass tube filled with a little neon gas! High-voltage electricity makes the gas glow orange-red.
How Can a Small Mirror Flash a Signal Across a Valley?
A small mirror can flash a signal across a valley because it can send light a long way! Tilt the mirror, and the bright spot jumps around.
Why Do Bike Reflectors Shine When a Car's Headlights Hit Them?
A bike reflector shines because it sends headlight beams straight back to the driver! It is covered in tiny three-sided mirror corners.
Why Do Crossing Guards and Road Workers Wear Bright Vests?
Crossing guards and road workers wear bright vests so drivers can see them early! The vests are bright yellow-green or orange, and they have reflective strips.
Why Do Bikes Need a White Light in Front and a Red Light in Back?
Bikes need a white light in front and a red light in back so others know where you are going! White looks like a car's headlight.
Why Does a Flashlight Look Weaker in Fog or Rain?
A flashlight looks weaker in fog or rain because tiny water drops scatter the light! Each drop bounces some light in every direction.
Why Do Some Lamps Look Warm and Yellow While Others Look Cool and White?
Some lamps look warm and yellow, and others look cool and white, because they give off different mixes of colors! Warm lamps have more orange and yellow.
Why Does a Flashlight Get Dimmer as Its Batteries Run Down?
A flashlight gets dimmer as its batteries run down because the battery is running out of energy! A fresh battery gives a strong push of electricity.
Why Is It Easier to Read When a Lamp Shines on the Page?
It is easier to read when a lamp shines on the page because the page gets plenty of light! Your eyes work best when the words are bright and clear.
Why Should You Never Look Straight Into Very Bright Lights?
Never look straight into very bright lights, because they can hurt your eyes! Your eyes handle ordinary daylight well, but they have limits.
Why Do Night-Lights Stay Dim on Purpose?
Night-lights stay dim on purpose because a little light is all you need! A dim glow lets you see shapes and find the door.
Why Do Exit Signs Stay Lit Even When the Power Goes Out?
Exit signs stay lit even when the power goes out, so they can always show the way! They have a small battery inside, and some glow with special paint.
Why Do Drivers Switch Off Their High Beams for Oncoming Cars?
Drivers switch off their high beams for oncoming cars because bright light dazzles other drivers! High beams shine far down dark roads.
Why Do Airplanes and Boats Have Red and Green Lights?
Planes and boats have a red light on the left side and a green light on the right side! In the dark, the colors tell you which way the vehicle is going.
Why Do Tall Towers Have Blinking Red Lights?
Tall towers blink red at night so airplane pilots can see them from far away! Red is easy to see against the dark sky, and it stands out from the stars.
Why Are Tunnels Extra Bright Near the Entrance?
Tunnels are extra bright near the entrance so your eyes can adjust! Going from bright sunshine into a dim tunnel feels like going into darkness.
Why Do Window Blinds Control How Much Light Comes In?
Window blinds control light with slats that can tilt up, down, or close! Tilting the slats changes where the light goes and how much comes in.
Why Do Lamps Have Shades?
Lamps have shades because a bare bulb is very bright and glares in your eyes! A shade covers the bulb and softens the light.
What Is Ultraviolet Light, and Why Can't We See It?
Ultraviolet light, or UV, has waves a little shorter than violet light, so our eyes cannot see it! The Sun gives off a lot of UV, and it can cause sunburn and hurt your eyes.
Why Are Special Eclipse Glasses Safe When Ordinary Sunglasses Are Not?
Special eclipse glasses are safe because they block almost all of the Sun's light! Ordinary sunglasses, even very dark ones, let in far too much.
Why Are Old Paintings and Photographs Kept in Dim Light?
Old paintings and photographs are kept in dim light because light can slowly fade them! Light carries energy.
Why Are Brake Lights Red?
Brake lights are red because red light can be seen from far away! Red is not scattered as much by fog, dust, and rain.
Why Do Emergency Vehicles Flash Red and Blue Lights?
Emergency vehicles flash red and blue lights because those lights are made to stand out! They are bright, they change quickly, and they use two very different colors.
Why Should You Keep Paper and Curtains Away From Hot Lamps?
Keep paper and curtains away from hot lamps, because some lamps get hot enough to scorch them! Heat can even start a fire if something stays too close for too long.
Why Can You See a Line of Light Under a Closed Door?
You can see a line of light under a closed door because light squeezes through the gap! Light travels in straight lines, and it also bounces.
Why Do Some Athletes Put Dark Marks Under Their Eyes?
Some athletes put dark marks under their eyes to cut glare! Dark patches absorb light that would bounce off their cheeks into their eyes.
What Is Light Really Made Of?
Light is a form of energy that travels as waves! It also comes in tiny packets called photons.
From Book 1: The Great Expedition (13)
Why Do Butterfly Wings Have Colors? Paint vs. Tiny Mirrors!
Butterfly colors come from two tricks. Some color is pigment, which is like nature's paint that soaks into things.
Why Do Fireflies Light Up? A Cold, Glowing Code!
Fireflies make light right inside their bodies! Special chemicals called luciferin and luciferase mix with oxygen in the abdomen to create a glow.
Why Is the Sky Blue? A Trick Light Plays in the Air!
Look up on a sunny day and you are seeing a cool trick of light. Sunlight looks white, but it is made of all colors mixed together.
Why Does Thunder Follow Lightning? Light Wins the Race!
Flash first, boom later! A lightning bolt is super hot and heats the air around it to hotter than the surface of the Sun.
Why Do Rainbows Appear? Light Bends and Splits!
Rainbows look like magic, but they come from light, water and a little science. Sunlight shines into tiny drops of water in the air, bends and splits into all its...
Why Do the Northern Lights Glow? A Sky Full of Color!
The Northern Lights are a glowing show high in the sky. The Sun sends out streams of charged particles, and Earth's magnetic field acts like an invisible shield that guides them toward the North and South Poles.
Why Do Eclipses Happen? Shadows in Space!
Eclipses are shadows in space. In a solar eclipse, the Moon passes between Earth and the Sun and casts a shadow on Earth, and in a lunar eclipse, Earth passes between...
Why Do Telescopes Help? Seeing Far Into Space!
Telescopes help us see far into space, way beyond what our eyes can see on their own. They use large mirrors or lenses to gather much more light than an eye can, then bend and focus that light so images look clearer.
What Is a Light-Year? It's Distance, Not Time!
A light-year sounds like a length of time, but it is really a distance. It is how far light travels in one year, and the page says light zips through space at 300,000 kilometers per second.
How Does a Light Bulb Work? Filaments vs. LEDs!
In an old-style bulb, electricity flows through a thin part called a filament, and it gets so hot that it glows. LED bulbs glow with tiny chips and give off less heat.
Why Do Glasses Help You See? Bending Light Just Right!
Glasses help by bending light. Your eyes bend light onto the back of the eye, but some eyes bend it too much or too little, so the picture does not land in the right spot.
Why Do Mirrors Flip Left and Right? Or Do They?
Mirrors seem to swap left and right, but the page says that is not quite what happens. A mirror bounces light straight back, so it flips front to back and not really left to right.
Why Do Cold Glasses Get Wet? The Water Comes From the Air!
Where does the water on a cold glass come from? Air holds invisible water vapor, and a cold glass cools the air right beside it.
From Book 2: The Inside Expedition (2)
Why Do We See Spots After a Bright Light?
After you look at a bright light, you may see a spot that floats around. That is because the cells in your eye stay busy for a moment.
Why Do Some People Need Glasses?
Some people need glasses because the picture in their eye does not land in the right spot. Glasses bend the light before it enters the eye.
From Book 3: The Built Expedition (5)
Why Do Lights Turn on with a Switch?
A light needs a complete loop of wire from the power source and back. A switch opens or closes that loop.
Why Do Light Bulbs Get Warm?
A bulb turns electric energy into light. Not all the electricity becomes light.
Why Do LED Lights Use Less Power?
An LED makes light inside a tiny chip, so almost no energy is thrown away as heat. An old-fashioned bulb glows by heating a thin wire until it's white hot, and that wastes lots of energy.
Why Do Shadows Happen?
A shadow is just a place the light could not reach! Light travels in straight lines.
Why Do Traffic Lights Change?
A traffic light is a turn-taking machine. It gives each direction a safe slice of time, so cars and walkers do not all move at once.
From Book 4: The Wild Expedition (8)
Why Do Plants Need Sunlight?
Sunlight is a plant's power source. Without it, chlorophyll cannot make sugar, and the plant slowly runs out of food.
Why Do Fireflies Glow?
The glow is a living lantern, used as a signal. Many fireflies flash to find a mate, and some young larvae glow too, as a keep-away warning.
Why Do Moths Fly to Lights?
Many night moths steer by a faraway light, like the moon. A porch bulb is like a fake moon that sits far too close.
Why Do We See Rainbows?
A rainbow is sunlight split apart and sent back by raindrops! Each drop acts like a tiny prism and a tiny mirror at the same time.
Why Do Fireflies Light Up?
A firefly's glow is a chemical lantern in its belly. A special reaction makes cold light with almost no heat.
Why Do Moths Fly at Lights?
Many moths steer by a distant light, like the moon. Keeping it at a steady angle works like a night compass.
Why Do Night Hikers Use Red Light?
Rod cells in your eyes do most of your night vision, and they respond much less to red light. A dim red light lets your eyes stay dark-adapted.
Why Should You Not Follow Glowing Eyes Off-Trail?
Glowing eyes are a clue, not an invitation. Off the trail there are roots, holes, and water, and you can lose the path fast.
From Book 6: The Ocean Expedition (4)
Why Can Some Fish Glow?
Some deep-sea fish make light inside their bodies with a chemical reaction. Others host glowing bacteria that live on them.
Why Do Corals Need Sunlight?
Many reef corals have tiny plant-like partners living inside them. They are called algae.
Why Does the Sea Sometimes Glow at Night?
Some tiny plankton and other sea creatures can make their own light! It happens through chemistry inside their bodies, and it is called bioluminescence.
Why Does Turning Off Extra Lights Help Hatchling Turtles?
Baby sea turtles hatch at night and crawl toward the brightest, lowest horizon, which is usually the sea. But street lights and porch lights can confuse them and pull them inland instead.
From Book 7: The Weather Expedition (12)
Why Do Sunsets Glow Orange and Pink?
Sunsets glow orange and pink because the Sun's light has to travel through much more air to reach you. Along that long path, most of the blue light is scattered away.
Why Do Rainbows Need Both Sun and Rain?
Rainbows need both sun and rain because sunlight has to pass through raindrops to make colors. Each raindrop bends and reflects light, and splits it into colors.
Why Is a Rainbow Curved?
A rainbow is curved because every raindrop sends colors back to you at a specific angle. All the drops at that same angle from your eyes form a circle in the sky.
Why Do Rainbows Show a Set Order of Colors?
Rainbows show a set order of colors because each color bends by a slightly different amount. Red bends least and violet bends most, so they leave the raindrop at slightly different angles.
Why Can You Sometimes See a Double Rainbow?
You sometimes see a double rainbow because light can bounce twice inside raindrops. The second bounce makes a fainter bow outside the main one, and its colors are reversed.
Why Can’t You Walk to the End of a Rainbow?
You can't walk to the end of a rainbow because a rainbow isn't a place. It depends on where you stand and where the Sun is.
Why Do Soap Bubbles Show Rainbow Colors?
Soap bubbles show rainbow colors because their walls are incredibly thin, and light waves interact inside them. Some colors cancel out, and others get stronger, creating shimmering swirls.
Why Do Oil Slicks Shimmer Like Tiny Rainbows?
Oil slicks shimmer like tiny rainbows because a very thin layer of oil on water works like a bubble wall. Light bounces off the top and bottom of the oil film, and the waves interfere.
Why Do Shadows Get Long in the Evening?
In the evening your shadow can stretch out like a giant, many times taller than you! A shadow forms when your body blocks sunlight.
Why Do Northern Lights Paint the Night (Aurora)?
Sometimes the night sky near the poles shimmers with green and pink ribbons called the aurora. Charged particles from the Sun crash into gases in the air high above Earth.
Why Does Glass Make Light Bend?
Look through a glass of water, and a straw can seem broken or bent! Light slows down when it travels into glass or water.
Why Does a Prism Split White Light?
Shine a flashlight through a prism, and a rainbow pops out of the other side! White light is secretly a team of colors.
From Book 9: The Food Expedition (1)
From Book 10: The Body Expedition (1)
From Book 11: The Animal Expedition (1)
From Book 12: The Volcano Expedition (3)
Why Does Lava Glow?
Anything extremely hot gives off light, and lava is extremely hot! The hotter it is, the brighter and yellower the glow.
Why Is Fresh Lava Dangerous Long After It Stops Glowing?
Fresh lava can look dark and solid after the top cools, but a thick crust can hide very hot rock underneath. That is why people stay far away from new lava, even when nothing glows.
Why Do Strange Animals Live By Vents Without Sunlight?
Strange animals live at deep ocean vents, where sunlight can never reach! Tiny microbes there make food from chemicals in the hot water instead of from sunshine.
From Book 15: The Robot Expedition (7)
How Does a Robot Use a Laser Beam to Map the Space Around It?
A lidar sensor uses laser light to map the space around a robot! It spins around and sends out thousands of short, safe laser pulses every second.
Why Do Robots Sometimes Get Confused by Bright Sunlight?
Robots can get confused by bright sunlight because many robot sensors measure light! Very bright sunlight can overload them, like a flash in your face.
Why Does a Robot with a Light Sensor Follow a Flashlight?
A robot with light sensors follows a flashlight by comparing left and right! It has one sensor on the left and one on the right.
How Does a Light Curtain Stop a Factory Robot When Someone Gets Close?
A light curtain stops a factory robot by using a row of invisible light beams! A sensor on the other side checks that each beam arrives.
Why Can Drone Light Shows Paint Pictures in the Night Sky?
Drone light shows paint pictures in the night sky because each drone is a flying dot of light! A computer plans where every drone should be at every moment.
Why Do Rovers Carry Rock-Zapping Lasers and Drills?
Rovers carry rock-zapping lasers and drills to find out what rocks are made of! A laser zaps a rock and makes a tiny puff of glowing gas.
Why Do Robot Builders Wear Safety Glasses?
Robot builders wear safety glasses to protect their eyes while they work! Building uses tools, springs, rubber bands, and small parts.
From Book 16: The Desert Expedition (1)
From Book 17: The Rainforest Expedition (4)
How Can a Frog Become See-Through?
Glass frogs have almost see-through bellies, and they can become even clearer when they rest! You can see their hearts and organs through their skin.
How Do Rainforest Plants Race Each Other for Sunlight?
Rainforest plants race each other for sunlight, and the race never ends! Down on the floor, it is very dark.
How Do Glasswing Butterflies Get See-Through Wings?
Glasswing butterflies have see-through wings because of tiny structures, not color! Their clear wings have almost no colored scales.
How Do Drones and Lasers Help Scientists Map a Rainforest?
Drones and lasers help scientists map a rainforest without climbing every tree! Drones take photos from above, and lasers measure the height of the forest.
From Book 18: The Polar Expedition (3)
What Does the Sky Look Like in the Blue Glow of Polar Twilight?
Polar twilight glows in deep blue, purple, and pink before the Sun returns and after it leaves! It can last for days or even weeks.
Why Are Shadows So Long Near the Poles?
Shadows are so long near the poles because the Sun sits low in the sky! A low Sun stretches shadows far across the ground.
Why Do Scientists Put Giant Telescopes at the South Pole?
The South Pole is a super place for telescopes! It is high, very cold, and extremely dry, so the air is clear and steady.
From Book 20: The Mountain Expedition (1)
From Book 21: The Magnet Expedition (1)
From Book 22: The Energy Expedition (5)
What Is Infrared Light?
Beyond the red light you can see, there is another kind of light. Your eyes cannot see it.
Why Do Very Hot Things Glow?
When something gets hot enough, it begins to glow. The hotter it gets, the more the color changes.
What Happens to Light When Something Swallows It?
When light hits something, it can bounce off or get swallowed. Swallowed light turns into heat.
How Do Solar Lamps and Small Grids Bring Light to Faraway Places?
Some villages are far from any power line. Still, they can have light at night.
How Do Motion-Sensor Lights Save Energy?
Some lights switch on all by themselves when you walk by. They are called motion-sensor lights.