Science

Most smoke detectors use an ion chamber that emits a steady stream of ions that get disrupted when smoke is present, setting off the alarm. Some smoke detectors use a photoelectric sensor instead that detects changes in a light beam when smoke hits it. Unfortunately, these are more expensive, and not as effective as the … Read more

Any liquid that expands in the heat and contracts in the cold would work, and you could use any of them inside a thermometer. The problem is finding a liquid that has a good workable range between its freezing and boiling points. Water, for example, has a freezing point of 32 °F (0 °C) and … Read more

Elementary science, my friend. Cold water is heavier, so it sinks to the bottom. The hot water rises to the top, which is also where you’ll find the outflow pipe, the one that goes to your hot water faucet. As a result, you’ll always be getting the hottest water in the heater. Most water heaters … Read more

Microwaves are radio waves with a very high frequency, which makes them very short, hence the “micro” in microwave. On your radio dial, you’d hear your microwave oven broadcasting at 2,500 megahertz, if your radio dial actually went that high. It doesn’t, 108 megahertz is the highest a standard radio picks up. A megahertz, by … Read more

You exceeded the liquid’s boiling point, and it exploded in the microwave oven, that’s what happened. Years ago, school teachers used to teach that water (unless pressurized) could never get hotter than its boiling point. That seemed true then, you put a pot on the stove, and it would bubble and boil furiously, allowing steam … Read more

Microwaves aren’t radiation, they’re radio waves, so microwaved foods never become radioactive in the first place. The way microwaves work is that they have a strong effect on water, twisting its molecules back and forth rapidly. As the water molecules rub back and forth against other molecules, they heat up from the friction. Luckily nearly … Read more

Metal in the microwave oven being dangerous is true enough that you’d want to avoid doing it. However, there are some loopholes. It turns out that some metal is worse than others. According to a physics professor at the University of Virginia, “Metal left in the microwave oven during cooking will only cause trouble if … Read more

Microwaves can pass through glass and plastic, but they can’t pass through metal. Strangely, they also can’t get through a hole that’s significantly smaller than their wavelength, so the fine metal mesh keeps them inside the oven, while letting some light out. In other words, your microwave oven is safe and your brain won’t fry … Read more

Both neon lights and fluorescent lights are long glass tubes with gas inside and an electrode on each end. Electrical currents pass through the gas from one electrode to the other, exciting the electrons enough that they emit light energy. The only significant difference between the two types of lights is the stuff that’s inside, … Read more

There’s a little bit of neon in the air we breathe, so yes, our atmosphere contains neon. You can extract it by using a process called adsorption. That involves superchilling the air at temperatures below —411 °F so it becomes a liquid. When you run the super cold liquid over charcoal, the neon molecules stick … Read more

Actually, saving energy by leaving fluorescent lights on all the time a myth that may have been true decades ago, when fluorescents required a hefty jolt to get them started. Nowadays, however, starting a fluorescent light takes only a small amount of extra electricity, so you’ll save electricity by turning the light off when it’s … Read more

Before we refute if windows get thicker at the bottom over years, let’s look at why some people have considered the idea plausible enough to make it the pernicious urban myth it has become. Their reasoning goes something like this: Solids and liquids have different molecular structures—the molecules of solids occur in regular patterns, while … Read more

Most glass is made of silica sand (silica, or silicon dioxide), with a little soda ash (sodium carbonate) and limestone (calcium carbonate) added to lower the sand’s melting temperature. Early humans got the idea for making glass after finding chunks formed by lightning strikes on the beach. These early humans originally cast it like metal … Read more

Making nearly perfect glass long eluded human ingenuity, as witnessed by the panes in old houses, in which imperfections in the thickness and surface create a subtle “fun house mirror” effect, distorting what you see outside. The ancient Romans never figured out how to make sheet glass for windows. They did try molding window glass … Read more

Although recent studies have shown that the brain can grow some new cells, you’d be wise to take good care of the ones you were born with. You can’t generate enough of the right kind to even consider riding your bike without a helmet, young man.

The old “we use only 10 percent of our brains” myth is so beloved by psychics, human potential gurus, and others who have made a cottage industry of hawking seminars and books. It’s not true. As it happens, you probably use all of your brain during a normal day, but not for every function. It’s … Read more

No, smarter people’s brains are not bigger and heavier than dumber people’s brains. There’s no apparent connection between brain size in humans and their intelligence. If that were the case, the average man would be 10 to 12 percent smarter than the average woman because men have larger brains by about a third of a … Read more

The part of the body that has the thickest skin is pretty much as you’d suspect. The soles of the feet and palms of the hands have the thickest layer of skin. After that, the back and nape of the neck are the thickest. The thinnest layer of skin is around the eyes, particularly the … Read more

Actually, your fingers and toes aren’t wrinkling at all but puckering from swelling. The thick outside layer of skin, called the stratum corneum, takes on excess water when saturated—sort of like when dried beans are soaked in water. The underlying skin and connective tissue around the stratum corneum doesn’t absorb water and therefore doesn’t swell … Read more

They’re called wisdom teeth because they’re the latest to arrive—when a person’s (presumably) older and wiser. The funny thing about our molars is that none of them form beneath any of the baby teeth. They develop only after our jaws grow big enough to make space for them. The problem arises when your jaw doesn’t … Read more

Other mammals do have what we call wisdom teeth, the molars that lie farthest back in the mouth. Often in humans, the jawbone is too small to accommodate these teeth, so they can’t break through the gums and become painfully wedged against the jaw and the other molars. In other mammals, however, their jawbones are … Read more

The opposite of cross-eyed is wall-eyed, but any kind of deviation from both eyeballs pointing straight ahead is called strabismus. The technical terms for these conditions are esotropia (cross-eyed) and exotropia (wandering eyes, or walleyed). Hypertropia is when one eye wanders up. About 5 percent of all children have some degree of strabismus, which most … Read more

Asians don’t actually have slanted eyes, —that’s an optical illusion, as it were. Folks from Asia actually have an extra fold in their eyelids called the epicanthic fold. It’s at the top of the eyelid and is elongated, sometimes extending beyond the eyelashes. Caucasian or African eyes have a slight, shortened fold where the epicanthic … Read more

An eyeball weighs about one ounce. You could send one in the mail for the price of a U.S. postage stamp. But make sure you mark it “Fragile.”

Yes, but the medical miracle of correcting blindness works better with those who’ve gone blind over the years, or those who were born almost blind—but not completely. There does seem to be a problem with suddenly getting sight if you’ve never had it before. Normally, the brain learns how to process visual information from the … Read more

In Europe and America, lefties make up 11 percent of the total population. And to answer your question, left-handed people are injured more often. Because they live in a world made for people who are right-handed, some recent studies have suggested that left-handed people are born with a weakened immune system and tend to have … Read more

Left-handedness is called Sinistrality. Right-handedness is called dextrality. It’s a sad case of right-handed bigotry that the word sinister comes from the name for left-handers, and dexterity from the name for right-handers.

The origin of the term southpaw reaches all the way back in time to, well, baseball. All baseball diamonds are created equal: the pitcher faces west, the batter faces east. This helps the batter survive a careening pitch by keeping the setting sun out of his eyes. It also means that the pitcher’s left hand … Read more

Sure, it happens all the time. The heart beats more than two and a half billion times in the average lifetime. In between each beat, the heart stops momentarily, meaning a total of twelve years of your life is spent with a stopped heart. Other than that, hearts can stop for a few minutes and … Read more

First, some background. The tip of the mammalian penis is called the glans. Although “glans” sounds a lot like “glands,” it actually has nothing to do with the production of hormones. Glans comes from the Latin word meaning “acorn.” It’s an odd sort of shape, isn’t it? One many of us have wondered about—, biologists … Read more

The first condom on record was made from a goat bladder by ancient Romans. But it wasn’t the first form of birth control. For at least 8,000 years, folks used coitus interruptus as a widespread and moderately effective form of birth control. It’s mentioned in both the Talmud and the Book of Genesis as a … Read more

It’s just more efficient that way. Nipples are one of the body parts that everybody gets issued early in life. They’re formed during the first fourteen weeks of development in the womb. The fact that everyone gets them sort of makes sense, since they begin growing before male or female hormones start flooding the fetus … Read more

Sure, there have been several experiments involving sex while in orbit. None of them, alas, have involved humans—at least, according to NASA. That makes it sound as if we don’t believe them. Frankly, we do, for a couple of reasons: Until recently, space trips have been relatively short—certainly not long enough for astronauts to start … Read more

No humans have floated away in space. So far that’s just the stuff of fiction and pop songs. As a matter of fact, all of the deaths to date have occurred during launch or reentry from outer space. The first to die was Vladimir Komarov in 1967. Several mechanical failures upon reentry into Earth’s atmosphere … Read more

No, astronauts can’t land on the dark side of the moon and here’s why. At the lunar equator, daytime temperatures can reach about 273 degrees Fahrenheit—a temperature that astronauts can tolerate in their space suits, although we’re sure they’d prefer a slightly cooler spot. At night when it’s dark, with no atmosphere to hold in … Read more

The predictable list of animals that have been sent into space includes dogs, monkeys, rats, mice, rabbits, and fish. No pigs, as of yet, but guinea pigs and pigtailed monkeys have all been put into orbit, as well as the eye lenses of pigs, cows, and sheep. Some not-so-likely animal crew members have included jellyfish, … Read more

The U.S. Space Command in Colorado Springs, Colorado, tracks about 10,000 objects or pieces of space junk in low-Earth orbit (300 to 1,200 miles up), and most, if not all, of these are man-made. They consist of about 100 space probes, 3,000 satellites (functional and not), and around 6,000 bits and pieces: lumps and chunks … Read more

Multiply your weight by 2.4. That’s how much you weigh on Jupiter. For the sake of clarity, let’s say you weighed an even 100 pounds. On Jupiter, you’d weigh about 240. Multiply your same 100 pounds by .38 and discover that on Mercury you’d be about 38 pounds. On the moon (multiply by .17), about … Read more

Planetary rings, found only on the outer planets, consist of pieces of ice and dust. In 1977 it was discovered that there were, indeed, rings around the planet Uranus. This was a surprise, as the rings are so dark that they’d been completely invisible up until that point. What made it possible to detect them … Read more

The moon has over 30 thousand billion craters that measure at least a foot wide, half a million of those with diameters over a mile. That’s a lot of holes and pockmarks, and there are a lot of names that have been given to moon craters over the years. Alas, “Scooby Doo” isn’t one of … Read more

New planetary moons in the solar system are discovered all the time. At this writing, Jupiter wins, hands down, with a total of thirty-nine —sixteen well-known moons and some lesser-known, more recently discovered moons. All of Jupiter’s major moons are named after mythological characters. Jupiter’s four large moons are Io, Europa, Ganymede, and Callisto. Jupiter’s … Read more

Objects in space do get confusing sometimes, so let’s see if we can clear things up a bit. Asteroids, sometimes called minor planets or planetoids, are small (in comparison to larger planets) planet like rocks that orbit the sun. They usually reside in the Asteroid Belt, which lies between the orbits of Mars and Jupiter. … Read more

At the equator, Earth spins at about 1,070 miles per hour. As you move north or south from there, the speed slows. Exactly at the poles—Earth’s axis points—the spin is much slower. Picture a record spinning. If you placed a toy at the center, then moved it an inch away from the center, then two … Read more

If Earth suddenly stopped, you’d experience quite a jolt. The atmosphere, of course, would still be in motion at the same speed that Earth had been rotating. This would lead to winds that would rub away mountains and land, smoothing Earth’s surface and removing every lump, bump, nook, and cranny on it. A gradual slowing … Read more

How fast other galaxies are moving away from us all depends on which galaxy, as they’re speeding away at different rates. On top of that, everything that’s speeding away from the Milky Way is accelerating. Here’s a sampling on either end: One of the slower galaxies is speeding away at about 5,040,000 mph. That’s like … Read more

The Earth’s rotation has been on a gradual slowdown since its birth. The day lengthens every 100 years by about .0015 seconds. It’s not much, mind you, but in several billion years it all adds up. At that time, for instance, a month will have increased from 27.3 days to 47. But don’t worry: we … Read more

No one knows for sure why the Earth’s axis is tilted, but many theorize that it was the result of a collision with a large planetoid during the last stages of Earth’s formation over 4.5 billion years ago. The theory is that the impact with this small, rocky planet not only knocked Earth to a … Read more

No, it’s not a dance move. The Chandler wobble is a slight wobbling of Earth on its axis. It got its name from the guy who discovered it was happening in 1891—S. C. Chandler. Still want to know how it’s done? If you’ve ever worked on a pottery wheel, you’re familiar with the concept. Earth … Read more

The space shuttle has to accelerate 2,000 mph every minute for the first eight minutes of its journey to leave Earth’s atmosphere. In terms of speed, from liftoff to exiting Earth’s atmosphere, the shuttle goes from 0 to 17,500 mph.

Jupiter is the biggest planet in the solar system. Jupiter is the largest planet in the Solar System and is the fifth planet from the Sun. The planet was named after the Roman God Jupiter by the Romans and it has over 60 moons orbiting it. Pluto, still officially called a planet, is the smallest.

The Sun’s apparent size at different times of the day is a matter of comparison. At sunset the sun is usually positioned near Earth’s horizon instead of directly up in the sky. The mind unconsciously compares its size to the size of the objects nearby. Next to trees, houses, roads, or buildings, it looks huge. … Read more

A solar eclipse happens when the moon’s shadow crosses Earth. A lunar eclipse occurs when Earth’s shadow crosses the moon. As Earth and the moon rotate, periodically they will fall into a perfectly straight line with the sun—it’s called syzygy. If Earth is in the middle of that lineup, with the sun on one side … Read more

The sun will eventually go out just like all the other stars in the universe. By looking at the rate at which the sun is consuming its fuel, scientists have estimated that it has about 5 or 6 billion more years of life in it before it begins to fade away. Actually, it will be … Read more

The theory of the Big Bang is that nothing, not space, not time, was here prior to the creation of the universe. About 15 billion years ago a primeval atom exploded, sending debris off in every direction at astronomical speeds. The theory itself will never be proved. The evidence for it, however, is compelling. Solar … Read more

Before our solar system existed there was a cloud of gases, the leftover stuff of dead stars. Debris, —bits and pieces of various elements from rocky sources— swirled in the gassy cloud. Over time, this large cloud collapsed in on itself and compressed into a rather large spinning disk. The disk continued to spin, further … Read more

The difference between a star and a planet is only a matter of size. The reason the sun “burns” is because it’s so big. The weight of the sun’s mass on itself crushes everything within its core—including tiny, usually uncrushable atoms. When atoms are broken, their innermost parts—the nuclei—freely bounce around and run into each … Read more

A black hole occurs when a large star, much larger than our sun, runs out of fuel. The remaining mass in the star collapses in on itself, causing a vacuum and sucking everything around it—including light—into the “hole.” That said, scientists have never actually seen a black hole. They are what’s called dark matter—they aren’t … Read more

It’s true. For most of us, telling the difference between Orion and Gemini would be next to impossible. It would seem like the ancients,— those who named the star clusters —had a little more imagination than they should have. Like cloud-watching, stargazing is a very personal thing. Each culture saw something different in the heavens. … Read more

Proxima Centauri, a.k.a. Alpha Centauri C is the closest star to our solar system. It’s 4.2 light-years away.

The Betelgeuse star is the bright red star in the Orion constellation. The name Betelgeuse is Arabic, and it generally means “the armpit of the mighty one.” If you look at the constellation, you can see it firmly planted where the hunter’s pit would be. Betelgeuse is approximately 640 light-years from the Earth and is … Read more

Some of the brighter, more prominent stars in the sky were given formal names—usually by the ancient Arabians—while others were named by European astronomers in the seventeenth and eighteenth centuries, based on the Greek constellations they resided in. The vast number of stars in the sky, however, soon ran these old naming systems dry. Catalog … Read more

It’s a plausible theory, on the face of it. Dust does seem like some sort of weird alien thing, in that it appears from nowhere and doesn’t seem to be the same dirt, sand, and other stuff you find blowing around outside. Furthermore, it’s a known fact that about a thousand tons of cosmic dust … Read more

Dust Mites are not a type of flea. They belong to the arachnid family, along with spiders, ticks, and harvesters, also known as “daddy long legs”. Dust mites feed on dead human skin that is shed. And we sure do shed a lot of skin. Up to 75% of household dust is composed of dead … Read more

It’s not just an illusion, most —electronic equipment does indeed get dusty faster than other household furnishings. Dust gets drawn to electric and magnetic fields given off by TVs, stereos, and computers. In fact, it’s one of the reasons so many computers are beige. Apple Computers ran tests when designing the first Macintosh in 1977 … Read more

Fear of dust is called Koniophobia. Not to be confused with amathophobia, which is the fear of sand. People who have a fear of dust sometimes have OCD or Obsessive Compulsive Disorder. It could also mean you’re just very clean or a neat freak. Fear of sand could often result after your older brother buries … Read more

Cat paraphernalia historians say that Sir Isaac Newton got tired of his cat Spithead interrupting his thoughts with all that “Let me out / Let me in!” caterwauling. So, no doubt using various advanced principles of gravity and inertia, Newton designed the first cat door. Although he probably didn’t file a patent for it. Cat … Read more

Oh, those chemistry majors. The “Maillard reaction” refers to the chemical changes that occur when you make toast. The name honors L. C. Maillard, the French chemist who in 1912 first discovered that bread’s starches and sugars caramelize into intense new flavors when toasted. Other foods can occur in many other foods including, Biscuit, Malted … Read more

The United Nations keeps a registry and a data center at NASA assigns designations, but only communications satellites are subject to practical controls. Every satellite must be registered to a particular country, for reasons of liability under space law. A registry has been maintained by the UN Secretariat since 1962, and another registry, established under … Read more

The planets are believed by many authorities to have coalesced from a cloud of gas early in the evolution of our solar system, beginning roughly 5 billion years ago. Since the gas cloud was disk shaped, when the planets came to be within this cloud, they all formed basically along the same plane. There is … Read more

A coronagraph is an optical device that blocks the light from the Sun’s disk, making it possible to observe the corona, the very thin and hot upper level of the solar atmosphere, at the edge of the disk. A lens focuses an image of the Sun onto a masking or occulting disk that prevents the … Read more

No, Pluto and Neptune won’t collide. Their closest approach is not close at all about the distance between Uranus and the Sun. One reason they cannot pass any closer is that Neptune completes its orbit three times in the time that Pluto goes around twice. This exact relationship is called a resonance. Another such relationship, … Read more

It would be accurate to say that the ancient Maya of Central America, who had no telescopes, did not measure Venus itself but kept careful records of its apparent track in the sky. Because of the relative orbits of Earth and Venus, Venus is first invisible, then appears in the morning sky, then disappears, then … Read more

The best idea scientists have of the geochemistry of Mars comes from the two Viking robots that landed on Mars in 1976. Findings from the robots’ weeks of readings of things like the Martian atmosphere are compared with the chemical signatures of meteorites found on Earth. The first such object confidently identified as Martian was … Read more

Venus is brighter than Mercury because it is much larger, because it has a reflective atmosphere, and because it makes close approaches to Earth. First, Mercury is about 3,100 miles in diameter, compared with about 7,700 miles for Venus. Second, there is no atmosphere surrounding Mercury, while Venus has a thick atmosphere, composed chiefly of … Read more

A small, well-defined crater named Airy-0, near the planet’s equator, was designated as the starting point for the 360 degrees of Martian longitude. The satellite Mariner 9 began photographing Mars on November 13, 1971, sending back thousands of detailed pictures of the planet’s surface on which to base a map. Using the information captured by … Read more

The Moon has an atmosphere now, though it is a very thin and highly dispersed collection of molecules, not suitable for breathing by Earthlings. The existence of a lunar atmosphere was reported in 1933, based on observation of the Moon using a mask that filtered out moonlight in order to study the spectrum of light … Read more

The speed of light can seem fairly slow when you’re talking about communicating across galaxies. FM broadcasts and the earliest television programs from, say, half a century of broadcasting have reached a distance of 50 light-years, or about 294 trillion miles, from Earth. The nearest star is about 4 light-years away, and there are on … Read more

Ordinarily, the mid-September harvest moon is no brighter than any other full moon, but it does provide more hours of moonlight. In autumn, the orbital path of the Moon and its visibility in the sky combine so that it stays above the horizon for an unusually long time at the full moon and a day … Read more

Such a transmission might take many forms, but would probably encode mathematical formulas. The reply would depend on the content; it would not be made by scientists, but would come after extensive international consultation. As for verification, the main feature distinguishing signals produced by a transmitter from those produced by natural processes is their spectral … Read more

The closest thing to a south star for navigators south of the equator is a pair of stars in the Southern Cross, Crux Australis (or just Crux to astronomers). Alpha Crucis (its brightest star) and Gamma Crucis (the third brightest) point almost straight to the south celestial pole. The striking Southern Cross, which has four … Read more

Because the eye has two kinds of receptors, cones for fine resolution and color and rods for dim light, and the rods tend to be located around the periphery, for viewing the edges of the field of vision. Cones are extremely good at high definition and for precise positioning of pinpoints of light. Rods don’t … Read more

Such pictures do not ordinarily show stars because the stars are not bright enough in comparison to the nearby Sun and the things it shines on. Virtually all of the astronaut photos are of objects brightly illuminated by the Sun. To capture them on film without overexposing the image, you need a relatively short exposure, … Read more

You might not die right away, but you would eventually be pulled apart by the force of gravity. As you fell in and even afterward, you might not lose consciousness, but the pull of gravity on your feet would be stronger than on your head, and you would be stretched, then torn apart. The difference … Read more

Most astronomers would say no. There is no known mechanism that would give the universe so much angular momentum, or spin, at its beginning, and few mechanisms for adding spin later. To know for sure if the universe rotates, scientists would need to know the velocities of millions of galaxies, over all regions of the … Read more

Stars are being born as well as dying, but the rate varies greatly from galaxy to galaxy. Stars form from huge clouds of dust and gas. If a cloud begins to contract because of its own gravity, its interior heats up as gravitational energy is converted to heat energy, reaching millions of degrees, and nuclear … Read more

Many insect species swarm, both the beneficent (like honeybees) and the irritating (like mosquitoes). In many cases, springtime swarms consist of groups of males all looking for suitable mates. Pheromone signals probably keep the group together. As insect mating, egg laying, and hatching tend to take place in synchronized waves, it is not surprising that … Read more

The number of individuals and species would depend on many variables, like soil condition and chemical use, but if the first few inches of soil were included, the totals might be impressive. One survey of backyard insects in the 1930s collected 1,402 species, including 467 butterflies and moths, 258 flies, 259 beetles, and 167 wasps, … Read more

Depending on the part of the country, time of year, and time of day, they could have been anything from flies to moths to dragonflies. Especially in the South, the most likely culprit is flies, and fly populations are highly cyclical. In coastal Florida, Alabama, Mississippi, and Louisiana, lovebugs the bibionid fly species Plecia nearctica … Read more

Yes, but only if pollen falls on the silk. Otherwise, a kernel does not develop. A corn plant produces corn silk surrounding each ear about two months after the plant emerges from the ground. The plant matures after about four months. Tassels, the male part of the plant, emerge at its apex and shed pollen … Read more

Members of the Loranthaceae family like the American mistletoe, Phoradendron flavescens, take food from the sap of woody plants through special roots called haustoria. Mistletoe also grows on other deciduous trees, including the sweet gum and red maple.