Helium is lighter than air and just as the heaviest things will tend to fall to the bottom, the lightest things will rise to the top. Helium weighs 0.1785 grams per liter. Nitrogen, which makes up 80% of the air we breathe, weighs 1.2506 grams per liter.

Basically, if you were to fill a soda bottle with helium and another with air, the one filled with helium would weigh a gram less than the bottle with air. It doesn't sound like a lot, but that's usually why blimps and balloons are usually really big, the one-gram difference really adds up in large volumes. Helium balloons follow the same principle as you do when you float in the water; the law of buoyancy. If the water you displace weighs more than you do, you will float.

Helium isn't the lightest element, hydrogen, weighing a mere 0.08988 grams per liter, is.

Wondering why we don't use that instead of helium?

Well, hydrogen balloons used to be really popular, but it is extremely flammable. The slightest spark will set off a huge explosion. The Hindenburg catastrophe was a direct result of that.

Did you know?
· Helium is a colorless, odorless, tasteless inert gas at room temperature and makes up about 0.0005% of the air we breathe.
· Helium's principal source is natural gas wells where it is extracted from the crude natural gas stream and purified and that it can be stored and shipped either as a gas or a cryogenic liquid.

Surface tension plays matchmaker in changing the status of a bubble from being single and solitary, to being part of a couple, or part of a multiple bubble group. Uniting the bubbles temporarily destroys the surface tension's equilibrium, but once the surface tension joins the bubbles, it establishes a new balance.

The internal air pressure of the single, solitary bubble slightly exceeds that of the air surrounding it, because the surface tension reduces the bubble's surface as it squeezes it into its round shape. The product of being squeezed is a buoyant bubble, which rises to the top of the water's surface, because of its own inner water level. The bubble happily floats about, surrounded by uniform surface tension, guided by the momentum it picked up when being formed, and by changes in air pressure.

In turbulent water, the surface tension pulls the water's surface into a slope, or meniscus, the bubble rides the wave, and floats to its crest. The meniscus, though it does not extend far into the water, manages to divert the bubbles' attention away from each other to objects, such as the sides of the bathtub, a human body, a rubber ducky, etc. Because the slope's extension range is short, the range of the force between the bubbles is also short.

Two or more bubbles drifting close to each other do not pass each other like ships in the night if their surface tensions overlap. This overlap destroys their equilibrium, and, to compensate for the low tension between the bubbles, the high surface tension surrounding them forces them together and restores their equilibrium. If, however, the surface tension forces them together too rapidly, we have a case of fatal attraction, as the two bubbles collide and burst.

Technically speaking, when the bubbles meet, they join at the point of the smallest surface area and, if they join in the middle of calm waters, the energy level they give off as they connect can be seen to the naked eye as circular ripples. Alone together at last.

Most of us who have ever cleaned a house would be much happier if there were less dust.
However, without dust there would be less rainfall and sunsets would be less beautiful.

Rain is formed when water molecules in the air collect around particles of dust. When the collected water becomes heavy enough the water droplet falls to the earth as rain. Thus water vapor could be much less likely to turn to rain without the dust particles.

The water vapor and dust particles also serve to reflect the rays of the sun. At sunrise and sunset, when the sun is below the horizon, the dust and water vapor molecules reflect the longer, red, wavelengths of light such that we can see them for more time (starting earlier in the case of sunrise and lasting longer in the case of sunset) than any of the other wavelengths. The more dust particles in the air the more colorful the sunrise or sunset.

The sky appears blue to us on a clear day, because the atoms of nitrogen and oxygen in the atmosphere separate the suns white light into its many colors, and scatter them throughout the atmosphere. The wavelength of the blue light scatters better than the rest, predominates over the other colors in the light spectrum, and makes the sky appear blue to us.

The scientific name for this phenomenon is the Tyndall effect, more commonly known as Rayleigh scattering.

This phenomenon describes the way in which light physically scatters when it passes through particles in the earths atmosphere that are 1/10th in diameter of the color of the light. The light spectrum ranges in wavelength from red to violet, and, since the wavelength of the blue light passes through the particles with greater ease than the wavelengths of the other colors of light, the sky appear blue to the naked eye.

The human eye has three types of light receptors, known as cones, located in the retina. The cones are either considered to be red, or blue, or green, based upon their strong response to light at these wavelengths. As light stimulates these receptors, our vision translates the signals into the colors we see.

When gazing at the sky, the red cones respond to the small amounts of red light scattered, and even less strongly to the orange and yellow wavelengths. Although green cones respond to yellow, their response to scattered green and green-blue wavelengths is stronger. Finally, colors near the strongly scattered blue wavelengths stimulate the blue receptors.

In short, the skylight stimulates the red and green cones almost equally, while stimulating the blue cones more strongly. For these reasons, our vision naturally adjusts as clearly as possible to separate colors.

Germs are tiny organisms that creep into our bodies and attack our immune system.

Unable to live on their own, germs invade our bodies and steal the nutrients and energy that our bodies produce. After gobbling up all of our nutrients and vitamins the germs leave behind their own harmful wastes called toxins. These toxins are the sources of our runny noses, high fevers, diarrhea and hoarse coughs.

Think back to the last time you were sick. Did you have a fever, runny nose, stomach ache, or throw-up often? Did you have to visit your doctor? Did you need medicine to help you get better.

Well… did you ever wonder why or how you became sick? Chances are that germs were the source of your illness.
There are many different kinds of germs, but the four most common are: bacteria, viruses, fungi and protozoa. Each of these types of germs cause different symptoms or illnesses. For instance, while bacteria germs cause minor illnesses such as ear infections, sore throats and cavities, viruses cause more serious diseases such as chicken pox, measles and the flu.

Although germs are everywhere, most of the time we don't realize that we have germs because they are so small that you need a microscope to see them. Germs spread through the air when someone coughs or sneezes. Or germs can also appear in bodily fluids like saliva, sweat and blood. The best way to avoid getting germs is stay away from these areas where germs spread. But the easiest way to protect yourself from germs is to wash your hands with soap and water frequently. You should always soap up your hands with suds after using the bathroom, after touching money, after playing outside or after visiting a sick friend or relative.

Yes!

At least three different plants turn the tables on insects and eat them instead of the reverse. Each passively, but cleverly, lures its prey, captures its kill with ease, digests its meal by using its plant juices, and then prepares for its next unsuspecting victim.

The pitcher plant of Borneo and of tropical Asia, which has a back-up lure in place should the first fail, is the most notorious of the trio. This plant exudes the scent of sweet nectar that most insects find appealing, and when one approaches to investigate, it finds an equally attractive pitcher-shaped plant with a red-hued rim and cover. Once the insect steps over the rim to drink from the plant, it loses its footing on the smooth interior, slides to the bottom of the abyss, and lands in a pool of liquid, which digests the victim once it has drowned.

The Sundew plant, aptly named for the sticky fluid on the upper part of each leaf that appears to the insect to be dewdrops, packages its victim before digesting it. Small, hair-like projections, which cover the surface of each leaf, are responsible for the sticky fluid on each leaf that lures the insect to the plant. Once the insect touches one of these "hairs," it is stuck, and the other hairs on the upper side of the leaf bend inward towards the center of the leaf, to wrap it in a neat, tight package, thus ensuring that it will stay for dinner. The "dew," which for the insect turned out to be a don't, digests it over the course of two days, after which the crafty hairs reopen for business.

The Venus's-flytrap, hailing from parts of North and of South Carolina, is the most gripping of these predatory plants, and practices true Southern hospitality by inviting any fly to stop by at any time. The plant waits for visitors with its leaves spread open and, when a fly happens by and touches one of the hairs that rim the plant's leaves, the Venus's-flytrap snaps its jaws shut, and has lived up to its name. After the plant's juices digest the fly, its leaves reopen, and the unassuming plant awaits its next caller.

Contrary to popular belief, "falling stars" are not stars at all, but are meteors, solid bodies that travel through space.
Meteors, ranging in size from that of a pinhead, to many tons, are visible to the naked eye at night, when the friction between the surfaces of the meteors and of the air, produces heat as the meteors enter the earth's atmosphere. The intense heat incinerates the meteors, which leave a blazing trail of light in their wake.

Most meteors do burn up when they enter the earth's atmosphere, with the exception of the large meteors, which are dragged through the earth's atmosphere by the earth's gravitational pull. After successful landings upon the earth, these huge bodies are renamed meteorites. Some scientists theorize that thousands of meteors fall to the earth during the daytime and the nighttime, but this theory is impossible to prove or to disprove, as most would necessarily land in water, which covers most of the earth's surface.

Generally speaking, meteors and meteor particles travel together in swarms like bees, with the exception of the loners, and travel in any direction they choose. Nature's spectacular fireworks show, a "meteor shower," comes into view when the swarms encounter the upper layer of the earth's atmosphere during the earth's perpetual revolution around the sun. The friction produced when the meteors and the meteor particles rub against the atmospheric air incinerates the swarms, and they fall towards the earth in a brilliant display of light.

The source of meteors traveling through space has yet to be explained satisfactorily. For thousands of years, the common belief held, was that meteors, or "falling stars," were literally from out of this world. In 467 BC, Roman historians recorded the extraordinary fall of a meteor to the earth.

Today, astronomers espouse the theory that comets spawn the swarms. The comets' offspring, the meteor swarms, travel in regular orbits, similar to the earth's orbit around the sun. One must be quite patient to witness such a swarm, or a meteor shower, as the swarms cross the earth's path only once every 33 years. This spectacle of light is, however, well worth the wait.

Bright marshmallow-colored snow blinds us with its gleaming white color because it reflects beams of white light. Instead of absorbing light, snow's complex structure prevents the light from shining through its lattice formation.

A beam of white sunlight entering a snow bank is so quickly scattered by a zillion ice crystals and air pockets that most of the light comes bouncing right back out of the snow bank. What little sunlight is absorbed by snow is absorbed equally over the wavelengths of visible light thus giving snow its white appearance.

So while many natural objects get their blue, red, and yellow colors from absorbing light, snow is stuck with its white color because it reflects light.

Quicksand consists of a buoyant blend of round granules of light sand, blended with water, or of light soil and gritty mud, or of mud peppered with pebbles. Water injects itself into the grains of any one of these mixtures, which separates and lifts them, causing them to tumble over one another, and rendering them helpless to support weighty objects.

Quicksand typically surfaces near the deltas of mighty rivers, or near shores, where a layer of stiff clay below collects and retains the water. Quicksand does not suck unsuspecting victims to their untimely deaths, a theory espoused my most until recently. This nightmarish theory did, however, provide good fodder for a host of low-budget horror films!

The discovery of quicksand's buoyant properties, akin to those of the salty Dead Sea, quashed this prevalent theory. Since quicksand is saturated with liquid, and far outweighs water, it allows anything or anyone who steps into it, to float higher than possible in water alone. The key to swimming in this non-chlorinated swimming hole, is slow motion. By moving slowly, when initially landing in quicksand, one provides the quicksand with the lead-time necessary to flow around one's body, thereby making swimming or floating possible.

The typical, bright, yellowish-orange upper part of a flame is due to the heating of unburned carbon particles.
The temperature of the fire and the material being burned are the factors that determine the color of the flame. The various colors of flames in a wood fire are due to the different substances in the flames.

The strong orange color of most wood flames results when sodium contained in the wood is heated.

The temperature of wood flames is lower than that of candle flames, which colors the wood flames orange, not yellow. If, however, some of the carbon particles in the fire are very hot, the color will be yellow. The product of the burnt carbon, when it has cooled, is black soot.

Since fire needs oxygen to burn, and since the bottom of a candle flame does not get much oxygen, it is the hottest spot in the flame and is blue in color.

The flame cools and changes color as it moves away from the source of the flame, because it is exposed to more oxygen. The temperature change causes the color of the flame to change from blue, at the hottest, lower portion of the flame, to the typical, bright, yellowish-orange or bright orange color with which most people are familiar with. Which shade of orange is seen at the upper portion of the flame, where the flame is the coolest, depends upon the material being burned.

Fall back, spring ahead…

Daylight saving time, the brainchild of Benjamin Franklin during his 18th century Parisian days, seems to increase the number of productive daylight hours we have, during the seasons when the sun sounds revile early. Today, the additional hour of sunlight we gain, by setting our clocks one hour ahead of time, allows us to close up shop an hour early, and to enjoy play time after the work day is done while the sun still beams high above us.

The extra daylight hour we now enjoy, by altering our circadian rhythms by one hour, did not immediately gain acceptance during Benjamin Franklin's time. Instead, the practice was born of necessity during World War I and II. The practicality of his idea came into play during these wars, when scarcity and rationing were the operative words. By following their normal routines, and by going to bed hours after sundown, people relied upon artificially generated light, which depleted the scarce reserves of fuel in its generation. Germany realized that this precious commodity could better be used to serve the war effort, and instituted the first daylight saving laws in 1915. Those who refused to comply with the lights out curfew faced punishment.

England followed suit in 1916, and, finally, the United States, in 1918. The United States reinstated the daylight saving laws on a national basis during World War II. The close of the war ended the law's necessity, but the national habit continued on a voluntary basis. Daylight saving time had taken root in our society, and was now the norm. Of course, daylight saving time never effected the farmer, whose livelihood dictates that he adheres to the old adage "Early to bed, early to rise."

The moon, a satellite, or small body, rotates on its axis around the earth, and "shines" when the sun's light beams onto its surface, and is reflected back to earth. Unfortunately, only one side of the moon is visible to us on the earth, as it takes the moon the same length of time to orbit on its axis, as it takes for it to orbit the earth.

The lunar month is divided into halves. During the first half, lasting approximately 14 days, the sun's light unrelentingly strikes the moon, which has no atmosphere or air to protect it from these rays, and brings the temperature of the moon to above that of the boiling point. The second half of the lunar month plunges the moon into cold, dark nights.

Man has learned a great deal about the moon since the days when ancient man worshipped it as a goddess who ruled the night. Space flights made by the United States, the USSR, now Russia, and our Apollo moon landings, unlocked some of the moon's secrets, by enabling astronauts to collect the moon's soil and rocks, and to photograph the side of the moon invisible to us for scientific analysis. The primary goal of scientific studies of the data collected is to determine if, someday, man can actually inhabit the moon.