Karen Hill

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.

No, because even the largest carnivorous plants are only big enough to digest something the size of a frog, and the digestive enzymes they secrete are comparatively weak. Very rarely, a rat or bird has been found drowned in the liquid contained in the bottle-like appendages that hang from the vines of Nepenthes rajah, a … Read more

It may be that the rich orange smell of the fruit, which folklore has long rumored to be an insect repellent, scares them off, or it may be that the latex-rich leaves gum up the mouth parts of insects, eventually discouraging others. You could try leaving the fruit around your house, or experiment with planting … Read more

While not poisonous, large quantities of rhubarb, stems or leaves, offer possible risks, and the stems may be as bad as the leaves for susceptible people. To complicate things, some rhubarb chemicals can have positive or negative effects. In cell cultures using an extract of the entire plant, studies found some antimutagenic effects, depending on … Read more

With patience, a rose can be grown from a seed, and indeed all the Peace roses of today are descended from a plant grown in 1939 from a single seed nurtured by Francis Meilland, the hybridizer. But a random seed from a Peace rose or any hybrid would be unlikely to produce a plant like … Read more

Yes, there are such plants, called halophytes. Some are natural species that grow well when the water they get has a high salt content. Others are species that scientists are tailoring for the purpose by selective breeding or crossbreeding for salt-tolerance genes. Halophytes include grasses, shrubs, and trees. Some are edible crops suitable for areas … Read more

What you heard about is mycorrhizae, complexes formed by beneficial fungi and plant roots. There are many different ones, and particular plant species form relationships with particular species of fungi. There are three basic types, depending on where the complex is formed: endomycorrhizae, inside the root hair; ectomycorrhizae, outside the root hair, and endoectomycorrhizae, both … Read more

No, but certain species among the hundreds or thousands of known bamboos die off all at once after their single episode of flowering. That can create problems for gardeners who cultivate a particular ornamental type. More seriously, a mass die-off of a bamboo species in the phenomenon called gregarious flowering can endanger a species, like … Read more

The timing of leaf loss varies with species, site, and season. Day length and temperature are the two triggers for color change and leaf loss. The timing is usually species specific but is also related to site conditions. For example, a fairly dry midsummer to fall in the Northeast can mean that some trees drop … Read more

Evergreen trees do not keep their leaves indefinitely, but rather may grow new ones before the old ones fall, or keep some and drop others over a period of time. As any southern gardener can tell you, some broadleaf evergreens, like Magnolia grandiflora, drop their heavy leaves in a staggered cycle over the course of … Read more

Trees grow vertically because of two things: gravity and light. Geotropism, in which microscopic particles in plant cells react to gravity, tends to make the roots grow straight down, which means that the stems grow straight up. Phototropism tends to make plants grow vertically as well, following the direction from which light comes. Phototropism was … Read more

Let us assume that you get the biggest plain, enriched bagel analyzed by the U.S. Department of Agriculture, 4 inches in diameter, weighing 110 grams, about 3.8 ounces. The ingredients flour, water, salt, yeast, and malt, but no sugar, if it is a classic bagel —are boiled and then baked. They add up to 302.5 … Read more

It is really a physics problem involving the interaction of water with a carbohydrate, and the process differs from food to food. When you have a solid food that you want to be able to cook faster, such as rice, you hydrate it, then dehydrate it under controlled conditions, adjusting the chemistry and physics of … Read more

Asiatic ginseng, Panax schinseng, and the American wild ginseng, Panax quinquefolius, are closely related and similar in both appearance and effects. Siberian ginseng includes species of a different family, the Eleutherococcus family, which is not real ginseng. There is not a big medicinal difference between the two “real” ginsengs. Each has a slightly different composition … Read more

Fish contains quite a bit of a substance that gives rise to two chemicals that make the rotten-fish smell, while red meat has hardly any. The chemicals are trimethy lamine and dimethylamine, both derived from trimethylamine oxide, which is particularly common in the flesh of fin fish, especially cold-water, surface-dwelling ocean fish like the cod. … Read more

Like all vegetables and fruits, tomatoes differ somewhat in nutritional value from variety to variety, and even from season to season. For example, the U.S. Department of Agriculture lists different average nutrient contents for tomatoes harvested from November to May and for those from June to October. Many food values are comparable for red and … Read more

Temperature changes can either delay or hasten the ripening of bananas. The banana is a tropical fruit, adapted to ripen most quickly at a certain stage of its development and at a particular temperature and humidity. Bananas continue to ripen after they are harvested, with more and more of their starches converted into sugars by … Read more

The best-known method relies on the amount of a pepper extract mixed with water that a panel of tasters need to sense the heat. Invented in 1912 by Wilbur L. Scoville, a pharmacologist, the rating is given in Scoville units. The sample is dried and mixed with alcohol; then sugar water is added. The tasters … Read more

The skin that forms on the surface of milk when it is heated is a complex of casein, or milk protein, and calcium, and results from evaporation of water at the surface of the heated liquid and the concentration and coagulation of protein there. Skimming the skin off removes significant amounts of nutrients. Skin formation … Read more

Wine that is simmered for a long time in a stew would probably retain only a small fraction of its alcohol, but other dishes, like briefly flambeed crepes Grand Marnier or a soup with sherry added at the last minute, would probably still have enough to be of concern to those who want to avoid … Read more

Yeasts are simple one-celled plants, members of the large Ascomycetes family of funguses. The powder or cake sold for baking is billions of cells of one of 160 or so useful funguses that are called yeast. Commercial baker’s yeast is a pure, selected strain of Saccharomycee cerevisiae. It is a “tame” yeast, raised in factories … Read more

The holes in Swiss Cheese are made by sizable bubbles of gas produced by a special kind of bacterium in the cheese-ripening process. There are three basic steps in producing most kinds of cheese: making curds from milk, concentrating the curds, and ripening the curds. First, hungry bacteria, pure cultures of streptococci and lactobacilli, feed … Read more

What weather reports call black ice is not black at all; it just looks that way because it is transparent and whatever color the road’s surface is shows through. Whether ice on the road is visible depends on how it is formed. Rime ice, which is visible, forms when droplets of freezing drizzle adhere to … Read more

Some scientists think it is possible that volcanic activity might be at least partly responsible for the periodic weather phenomenon called El Nino. This theory was inspired in part by the discovery in 1993 of the largest known cluster of volcanoes, covering an area the size of New York State. The area in question is … Read more

Humidity is one of several atmospheric factors affecting the propagation of sound. Heavy, muggy air actually carries sound better. Bone-dry air greatly attenuates sound. But humidity is not as prominent a factor in affecting low-frequency sound as the bending of sound rays (or sound waves going in the same direction) by wind and the temperature … Read more

Considering the physical forces on precipitation as it falls, drops would probably be more properly described as shaped like a hamburger bun, flat on the bottom but rounded on the top. The shape of the drop as it comes down is ultimately a product of the interaction between the force of gravity acting downward and … Read more

Summertime conditions in the Rockies constitute a recipe for thunderstorms. The ingredients are strong sunshine coming at a direct angle to warm the land below, sharp differences in temperature between air warmed by the mountains and cooler air over adjacent plains, and enough water in the air. Thunderstorms owe their existence to thermals, or localized … Read more

A rain gauge shaped like a megaphone is not the standard shape meteorologists use, but it should work if it has the correct ratios between the cross-sectional area at the top and the part of the gauge that actually collects and measures the water. If this gauge was a straight-sided cylinder that did not narrow … Read more

Cloud-seeding experiments and government programs continue, but in this country at least, they are not regarded as a panacea for drought. The programs are usually subject to strict controls. Some thirty-two states have enacted laws regulating who can practice cloud seeding. Cloud seeding dates from experiments in 1946 at the General Electric Laboratories in Schenectady, … Read more

Contrails, or condensation trails, are clouds of ice crystals formed when hot, moist air from aircraft engines mixes with cold, drier air in the upper atmosphere. Contrails are similar to cirrus clouds, naturally occurring clouds found at altitudes around 20,000 feet. Portions of the upper atmosphere are too dry to produce condensation, so aircraft flying … Read more

When the National Weather Service forecasters use the term probability of precipitation, they mean that in ten instances of weather patterns similar to the one they are looking at, it rained five times. The service keeps cumulative records, and the probability forecast is a statistic based on what has happened. For example, if a cold … Read more

A cloud’s color depends chiefly on the cloud’s relationship to the light of the Sun. In some cases, it depends on the color of the surrounding sky. If a cloud covers the whole visible area of the sky, the depth of the cloud determines the color of the cloud; the deeper it is, the darker … Read more

The chief practical reason for setting the clock an hour later for a certain period of the year, so that the Sun sets later by the clock, is not to “save” daylight, but to make daylight hours coincide more closely with the time when most people use energy. A major effect of daylight saving time … Read more

It would have exactly twelve hours of daylight if this were an airless world with no atmosphere. However, Earth’s atmosphere acts like a lens and bends, or refracts, the Sun’s light above the horizon. When you see the disk of the Sun resting on the horizon at sunset, you are looking not at the Sun … Read more

Physicists say it is not so much that big stones work their way up as it is that smaller particles work their way down. Physicists have long known that in a mix of large and small objects, the large ones tend to end up higher while the small ones end up lower. This holds true … Read more

There are three basic channel patterns for a river: straight, meandering, or braided. Depending on such factors as terrain, soil, and water volume, different stretches of a river may show different patterns, and channels may shift over time. There is no fixed rule for the evolution of a river’s channel, but one typical progression is … Read more

The freezing temperature of water drops about 1 degree for every 75 of the units of pressure called atmospheres, but the change is small compared with the difference even one atmosphere of pressure makes in raising the boiling point. (One atmosphere is equal to 14.69 pounds per square inch.) Why deep sea water does not … Read more

One important reason is that the complex ecology of the prairie environment is formed by a cycle of fires and regrowth of a succession of fire-tolerant plants, and trees do not survive the periodic fires. The other limiting factor is a dry climate, affecting trees more than grassland plants, which hoard water. The fires sustained … Read more

Questions of pollution aside, the answer, oceanographers say, is that cold northern waters tend to teem with great concentrations of tiny plants and animals (phytoplankton and zooplankton), while southern waters are (in terms of numbers of individual organisms) empty deserts, with a few species-rich oases, such as coral reefs and waters fed nutrients by river … Read more

Rising sea levels worldwide following the last Ice Age are a more likely explanation for a great flood about 7,500 years ago, or 5500 B.C., that suddenly inundated areas around the Black Sea. Some scientists suggest it could have been the basis for flood stories in both the Hebrew Bible and the Babylonian epic of … Read more

Flood stage and crest have fairly simple definitions. The flood stage is the height of a river above which damage begins to occur, typically because the river begins to overflow its banks. The crest is the highest level that a river reaches. Prediction is a more complex matter, involving thousands of readings of river stages … Read more

In the 1960s, an Australian graduate student found rocks from an ancient aboriginal campfire, perhaps 30,000 years old, that were lying in place, magnetized in the opposite direction from the present-day orientation of the earth’s magnetic field. The student suggested to his amazed professor that this was evidence of a shift in the magnetic field … Read more

If there were a sudden overnight flip of the Earth’s magnetic field, scouts might be in trouble with their compasses, but most electrical appliances would not be affected. The compass needle is just a little magnet that lines up with the magnetic field lines of Earth; these imaginary lines converge on a spot near Greenland. … Read more