When waves of energy vibrate within your ears, you would possibly desire singing or dance. We tend to decision this music. It’s a special reasonably sound that we tend to fancy paying attention to as a result of it’s the ability to create us feel happy or unhappy. Music is formed by instruments that shake the air therefore the sound rushes toward us. Most instruments create a spread of sound frequencies, in order that they will play a musical tune.

Musical instruments create sound by moving the air back and forth all around them. The quicker they vibrate, the quicker they shake the air and also the higher the musical notes we tend to hear. Most instruments area unit designed in order that they will vibrate at slightly completely different speeds, creating many various notes. A stringed instrument has six strings, however you’ll press them in numerous places to create dozens of various notes.

Bottel organ
You’ll build associate organ by filling bottles with completely different amounts of water. Once you blow into a bottle, the air within vibrates, creating a musical notation. The fuller bottles create higher notes, whereas those with less water turn out lower notes.

We can produce associate infinite range of melodies by combining sounds from different instruments. Though every instrument makes sound waves, all of them work slightly otherwise. larger instruments tend to create lower and louder notes than little ones. Instruments with a lot of keys, strings, or holes will create a wider vary of notes. taking part in several instruments along in associate orchestra makes even a lot of fascinating effects.

It takes energy to provide sound, thus creating loud sounds for an extended time is difficult work. that is one reason why we’ve electrical instruments. They use electricity to assist us create loud sounds for long periods of your time.

Electric instruments additionally create terribly completely different sounds from ancient acoustic (nonelectric) instruments.


Ordinary acoustic guitars have strings that you just pluck. Once the strings move, they vibrate air within the wood case and this makes the sound. Electrical guitars have metal strings with pickups (wire-wrapped magnets) beneath. Once the strings vibrate, they create electrical currents flow through the pickups. If a stringed instrument is connected to associate electronic equipment and speaker system, these currents area unit boosted in volume to create loud music.



There might be no more enchanting experience to a fan of astronomy than viewing Saturn and its glorious rings through a small telescope. The scene is almost surreal: a shimmering, egg shaped orb hanging against the blackness of space and girded by what seems like an incredibly delicate, thin disk of material almost twice as wide as the planet itself. It is truly one of the gems of the sky.

Saturn is the second largest of the gas giants, more than nine times wider and nearly one hundred times as massive as Earth. The flat disk that circles the planet’s equator is, of course, the famous Rings of Saturn. Composed mostly of ice, the ring system is probably no more than 22 to 33 yards (20 to 30 meters) thick.

No one knows whether the rings of Saturn are an ancient, primordial feature, or whether they are a relatively new feature, perhaps formed from the catastrophic breakup of a former icy moon.

Accompanying Saturn are 62 known moons, hundreds of smaller “moonlets” embedded in the rings, and billions of ring particles ranging from the size of houses and cars to specks of dust. Saturn’s largest moon, Titan, is larger than Mercury and is the only moon in the solar system with a thick atmosphere.

Saturn’s clouds and haze bands are fainter and less colorful than Jupiter’s, although the composition of the atmosphere is fairly similar. Perhaps the biggest chemical difference between Saturn and Jupiter is that, for reasons not fully understood, Saturn has a little less helium relative to hydrogen, making it less “solar” than Jupiter.

Another mystery is why the wind speeds on Saturn are much higher than on Jupiter, or anywhere else in the solar system more than 1,120 miles (1,800 kilometers) per hour in places! Detailed studies of Saturn and Jupiter by the Pioneer, Voyager, Galileo, and Cassini spacecraft show us that not all gas giants are the same. As we discover more gas giants among the extrasolar planets, those worlds, too, are likely to be both lovely and enigmatic.



Our solar system is basically comprised of the Sun (about 99.8 percent), Jupiter (about 0.1 percent), and everything else. Jupiter is truly the king of the planetary realm, with more than twice the mass of all the other planets combined.
Sixty three known moons and a series of faint rings orbit this colossal world. Jupiter’s diameter is 23 Earths across; if it were hollow, more than a thousand Earths would fit inside.

Partly because of its enormous size and its orbital position at the inner edge of the outer solar system (around 5.2 astronomical units), Jupiter is the fourth-brightest object in our night sky after the Sun, Moon, and Venus. Jupiter is also luminous because its visible surface is made up of bright clouds.
Indeed, there is no “surface” visible on Jupiter or any of the other giant outer planets-everything we see is cloud or haze, made of exotic and sometimes colorful chemical compounds like methane, ethane, ammonium hydrosulfide, and phosphine. Winds traveling several hundred miles per hour twist the clouds into horizontal belts, and giant Earth-size storm systems, such as the Great Red Spot, have churned for many hundreds of years.

Below the clouds, Jupiter’s pressure and temperature increase dramatically, but the chemistry is, on average, much simpler: Jupiter is about 75 percent hydrogen and 25 percent helium, just like the Sun. In fact, if the Solar Nebula had been bigger and Jupiter had formed with about 50 to 80 times more mass, it would have become a star.

Jupiter’s formation has had a major influence on the architecture of the solar system, perturbing the orbits of the other giant planets, preventing a planet from forming in the region of the main asteroid belt, and gravitationally scattering asteroids and comets on orbits that caused impacts with other planets in the Late Heavy Bombardment. Some objects were even flung into the Kuiper Belt or out of the solar system entirely! Today Jupiter is a gravitational magnet, still occasionally drawing in small bodies such as Comet SL-9, which split up and smashed into its cloud tops in 1994.



We may have to go no farther than the next planet out to find out if life exists or ever existed-beyond Earth. Mars has seemingly always been the subject of fascination, from ancient times, when it was seen as a cosmic incarnation of the Roman god of war, to the twentieth century, when many imagined the planet to be the abode of Percival Lowell’s desperate canal builders.

Mars is a small planet, about half the diameter of Earth and only about 15 percent of its volume. For further reference, the surface area of Mars is about the same as the surface area of all of the continents on Earth. On average,the planet orbits about 50 percent farther from the Sun than we do. The thin Martian carbon dioxide atmosphere (only 1 percent as thick as Earth’s) can’t trap much heat, so the surface is very cold.

Daytime temperatures near the equator rarely rise above the freezing point of water, and nights near the poles routinely drop down to the freezing point of carbon dioxide (which is 150 kelvins, or about -190°F). Today Mars is a dusty world in a deep freeze.

And yet, spacecraft images, meteorites from Mars, and other data over nearly 50 years have shown that Mars is the most Earthlike place in the solar system (besides Earth itself), and that during its first few billion years, the Red Planet may have been a much warmer and wetter world.
What happened? Possibilities include gradual cooling of the planet’s core and solar wind or catastrophic impact destruction of the atmosphere. Determining how and why the planet’s climate changed so dramatically is a hot topic of research.

We’ve learned enough about the Mars of 3 or 4 billion years ago to know that parts of the surface and subsurface were habitable to life.
The next 50 years of Mars exploration will be all about expanding the search for habitable environments there and finding out if any were-or still are-inhabited.



Hydrogen is the lightest of all the elements. Each of its atoms has just one electron moving around one proton. Hydrogen accounts for about three-fourths of the mass of all the atoms we can see in the universe. On Earth, it is one of the elements in water (H2O), but as a gas it is only found in very small traces in our atmosphere. Since hydrogen burns easily in air and creates almost no pollution, it could become a fuel of the future.

Hydrogen is about 14 times lighter than air, so a balloon filled with hydrogen floats upward like a bubble in the heavier air around it. Many years ago, hydrogen was used in huge balloons and airships, lifting them up into the air. Since hydrogen catches fire easily when mixed with air, and even explodes, airships today use safer gases.

Hydrogen burns by combining with oxygen to produce water. A spacecraft’s rocket uses liquid hydrogen, along with liquid oxygen, as a fuel. These two elements are mixed in the spacecraft’s main rocket engines and then ignited.

As soon as hydrogen burns, it explodes, generating a thrust (a push with force) that lifts the spacecraft into space.

hydrogen could one day replace gasoline and diesel as a vehicle fuel. It can be combined with oxygen from air inside a fuel cell, generating electricity for an electric motor. Hydrogen-fueled cars produce only water in their exhaust.

In the 1920s and 1930s, gigantic hydrogen-filled airships carried passengers across continents and oceans. Then, in 1937, the hydrogen in the German airship Hindenburg caught fire, probably from a stray spark. The massive fireball and explosion killed 36 people. Since then, airships have mostly used other, less flammable gases.



It’s fun to ponder the relative importance of “nature versus nurture” in determining the origin of people’s personalities and characteristics. Twins, for example, make great case studies. Well, the same is true for planets, and one of the best examples to consider is Venus, a near-twin of Earth in some ways but profoundly different in others.

Venus is only about 5 percent smaller than Earth and has about the same density-meaning that it is essentially a rocky, terrestrial planet very much like our own. Both planets have atmospheres, and Venus even orbits in the same general neighborhood of the inner solar system as we do, at an average distance of 0.72 astronomical units compared to Earth’s 1.0. But that’s where the similarities end. Venus is barely spinning, taking about 243 Earth days to spin once on its axis-backward! The Venusian atmosphere is much thicker than ours, with 90 times the pressure at its surface. That thick atmosphere sports violent upper-level wind speeds of more than 218 miles (350 kilometers) per hour and is almost entirely carbon dioxide, with only scant traces of the nitrogen dioxide, oxygen, and water found in Earth’s atmosphere.

The carbon dioxide molecule is transparent to visible light but is exceedingly good at trapping heat radiation (like a greenhouse), causing the surface of Venus to be very hot more than 750 kelvins, or about 300 degrees hotter than an oven!

Astronomers are trying to understand how Earth and Venus ended up with such radically different surface conditions. Understanding carbon dioxide may be the key.

Earth has as much carbon dioxide as Venus, but it dissolves in our oceans and is trapped in rocky carbonate minerals.
Any ocean on early Venus, slightly closer to the Sun, would have since evaporated away, however, leaving no way to remove the carbon dioxide.

Venus is a case study of carbon dioxide gone wild and is a prime example of how studying other planets can help us understand what may be in store for our own world.

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All the planets in our solar system formed around the same time, about 4.5 billion years ago, as the Solar Nebula cooled and tiny grains condensed, collided, stuck together, and eventually grew into a small number of big objects, In the warm zone close to the Sun, the planets were rocky. Farther out, beyond the “snow line,” they were mixtures of rock, ice, and gas.

Mercury is the closest in of the so called terrestrial planets, with a diameter of 3,032 miles (4,880 kilometers); Earth’s diameter, by comparison, is 7,926 miles (12,756 kilometers). Mercury orbits the Sun at an average distance of only 0.38 astronomical units (or AU; 1 AU = 93 million miles = 150 million kilometers = Earth’s average orbital distance from the Sun).
Mercury is the Roman name of the Greek god Hermes, the fleet-footed messenger. The planet was aptly named: even the ancients knew that Mercury takes only 88 days to complete a circuit in the sky, which we now know represents its orbital period around the Sun.

Mercury is a small world of harsh extremes and curious enigmas. There is no atmosphere, and temperatures range from only 90 kelvins in permanently shadowed craters near the poles to more than 700 kelvins (above the melting point of lead) in the harsh midday sunlight. Earth-based radar observations indicate that there may be ice in those polar craters. Mercury has a very high density and a large iron core that spans 75 percent of the planet’s radius. The core might be partially molten, perhaps explaining Mercury’s weak magnetic field (1 percent as strong as Earth’s).

Images from the two space missions that have encountered Mercury (Mariner 10in 1974-1975 and MESSENGER in 2011 2015) reveal a heavily cratered surface and some evidence of ancient volcanic activity similar to the Moon’s. Perhaps most surprising, the planet preserves a network of large tectonic thrust faults (scarps) that seem to indicate that Mercury may have been completely molten early in its history and then shrank by a few percent when it cooled.


The compass app on your phone probably won’t work because it relies on radio signals that are easily blocked by rock or water, but for a compass with a wobbly needle, it just depends on how far underground.

A compass works because its magnetised needle lines up with the magnetic field that runs between Earth’s north and south poles, and that field is just as powerful if you go down a mineshaft or into the depths of the ocean.

But the field is created by swirling molten iron in Earth’s core, and if you could drill that far down, you’d find your magnetic needle going haywire.



Magnetism could be a force which will attract (pull toward) or repel (push away). Materials that are powerfully interested in magnetism, like iron or nickel, referred to as magnetism materials.

Repel or attract
A magnet has 2 ends, or poles-a north pole and a South Pole. once 2 magnets placed close to one another with like (the same) poles facing, the 2 poles can push one another away. If a pole is facing a South Pole, they’re going to pull toward one another.

Magnetic field
The area around a magnet wherever a magnetism will be detected is named its field. The field is strongest close to the poles. Dropping iron filings around a magnet reveals the form of its field.

The stronger the magnet, the larger its field are going to be.

Magnets in action
We use magnets in many various ways in which the motors within several machines driven by tiny magnets, whereas giant magnets will power giant objects like trains.

Magnetic Earth
Earth could be a big magnet. It’s encircled by a field, that is made by electrical currents deep within the planet’s liquid metal core. A compass works by sensing Earth’s magnetism. It contains alittle magnet, and therefore the South Pole of the needle points toward Earth’s direction pole.


When you see a airplane sweeping through the sky, or watch a automobile whizzing past, powerful engines area unit athletics within them. Most vehicles area unit supercharged by engines- machines that burn fuel to released heat. Even small amounts of fuel unharness vast amounts of energy after they burn. Engine turns this energy into kinetic (movement) energy.

What’s within associate degree engine?
Engines absorb fuel, burn it to unharness heat, and use that to form movement. In a very automobile engine, these items happen in durable “cooking pots” known as cylinders, with pistons at the lowest that pump up and down. Because the fuel burns, every piston pumps successively, driving a rod known as the rotating shaft. The spinning rotating shaft carries the engine’s power to the gears and wheels.


Automobile engines repeat four steps (strokes). First, within the intake stroke, mixed air and fuel area unit sucked in. Second, within the compression stroke, the piston squashes the mixture. Third, within the power stroke, a electrical device makes the fuel burn, expand, and drive the piston. Finally, within the exhaust stroke, the piston pushes waste gases from the cylinder.

The engines on cars, planes, trains, and rockets all add alternative ways. This is often primarily as a result of larger vehicles ought to build far more power than smaller ones. They need a lot of powerful engines, so that they will burn fuel a lot of quickly, build a lot of energy every second, and go quicker.

How will associate degree engine drive a machine?
Jet engines fireplace exhaust gases backward, that makes planes shoot forward. In cars and trains, the facility from the engine is employed to show the wheels. In ships (right) and tiny planes, the engines flip propellers, pushing air or water to power on.

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