RAMALAN BINTANG ABADI

Our Solar System

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Our solar neighborhood is an exciting place. The Solar System is full of planets, moons, asteroids, comets, minor planets, and many other exciting objects. Learn about Io, the explosive moon that orbits the planet Jupiter, or explore the gigantic canyons and deserts on Mars.

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What Is The Solar System?

The Solar System is made up of all the planets that orbit our Sun. In addition to planets, the Solar System also consists of moons, comets, asteroids, minor planets, and dust and gas.

Everything in the Solar System orbits or revolves around the Sun. The Sun contains around 98% of all the material in the Solar System. The larger an object is, the more gravity it has. Because the Sun is so large, its powerful gravity attracts all the other objects in the Solar System towards it. At the same time, these objects, which are moving very rapidly, try to fly away from the Sun, outward into the emptiness of outer space. The result of the planets trying to fly away, at the same time that the Sun is trying to pull them inward is that they become trapped half-way in between. Balanced between flying towards the Sun, and escaping into space, they spend eternity orbiting around their parent star.

How Did The Solar System form?

This is an important question, and one that is difficult for scientists to understand. After all, the creation of our Solar System took place billions of years before there were any people around to witness it. Our own evolution is tied closely to the evolution of the Solar System. Thus, without understanding from where the Solar System came from, it is difficult to comprehend how mankind came to be.

Scientists believe that the Solar System evolved from a giant cloud of dust and gas. They believe that this dust and gas began to collapse under the weight of its own gravity. As it did so, the matter contained within this could begin moving in a giant circle, much like the water in a drain moves around the center of the drain in a circle.

At the center of this spinning cloud, a small star began to form. This star grew larger and larger as it collected more and more of the dust and gas that collapsed into it.

Further away from the center of this mass where the star was forming, there were smaller clumps of dust and gas that were also collapsing. The star in the center eventually ignited forming our Sun, while the smaller clumps became the planets, minor planets, moons, comets, and asteroids.

A Great Storm

Once ignited, the Sun's powerful solar winds began to blow. These winds, which are made up of atomic particles being blown outward from the Sun, slowly pushed the remaining gas and dust out of the Solar System.

With no more gas or dust, the planets, minor planets, moons, comets, and asteroids stopped growing. You may have noticed that the four inner planets are much smaller than the four outer planets. Why is that?

Because the inner planets are much closer to the Sun, they are located where the solar winds are stronger. As a result, the dust and gas from the inner Solar System was blown away much more quickly than it was from the outer Solar System. This gave the planets of the inner Solar System less time to grow.

Another important difference is that the outer planets are largely made of gas and water, while the inner planets are made up almost entirely of rock and dust. This is also a result of the solar winds. As the outer planets grew larger, their gravity had time to accumulate massive amounts of gas, water, as well as dust.

The Solar System Has Over 100 Worlds

It is true that there are only eight planets. However, the Solar System is made up of over 100 worlds that are every bit as fascinating. Some of these minor planets, and moons are actually larger than the planet Mercury!

Others, such as Io, have active volcanoes. Europa has a liquid water ocean, while Titan has lakes, rivers, and oceans of liquid Methane. You can read more about these amazing worlds by clicking here.

The Asteroid Belt, The Kuiper Belt, And The Oort Cloud

You have probably heard about the Asteroid Belt. This band of asteroids sits between the orbits of the planets Jupiter and Mars. It is made up of thousands of objects too small to be considered planets. Some of them no larger than a grain of dust, while others, like Eros can be more than 100 miles across. A few, like Ida, even have their own moons.

Further out, beyond the orbit of the minor planet Pluto, sits another belt known as the Kuiper Belt. Like the Asteroid Belt, the Kuiper Belt is also made up of thousands, possibly even millions of objects too small to be considered planets. A few of these objects, like Pluto, are large enough that their gravity has pulled them into a sphere shape.

These objects are made out of mostly frozen gas with small amounts of dust. They are often called dirty snowballs. However, you probably know them by their other name... comets.

Every once in a while one of these comets will be thrown off of its orbit in the Kuiper Belt and hurled towards the inner Solar System where it slowly melts in a fantastic show of tail and light.

Beyond the Kuiper Belt sits a vast area known as the Oort Cloud. Here within this jumbled disorganized cloud live millions of additional comets. These comets do not orbit the Sun in a ring or belt. Instead, each one buzzes around in a completely random direction, and at extremely high velocities.

Beyond The Oort Cloud

The Sun's solar winds continue pushing outward until they finally begin to mix into the interstellar medium, becoming lost with the winds from other stars. This creates a sort of bubble called the Heliosphere. Scientists define the boundaries of the Solar System as being the border of the Heliosphere, or at the place where the solar winds from the Sun mix with the winds from other stars.

The Heliosphere extends out from the Sun to a distance of about 15 billion miles, which is more than 160 times further from the Sun than is the Earth.

Solar System Facts
Each page is full of fun and exciting facts about our Solar System. Take your time, and enjoy exploring our solar family.

Did you know that moons are also called satellites?

The Sun's Name Means:
The Romans called the sun Sol, which in English means sun. In ancient Greece, the sun was called Helios.

Our Sun is not unique in the universe. It is a common middle-sized yellow star which scientists have named Sol, after the ancient Roman name. This is why our system of planets is called the Solar System. There are trillions of other stars in the universe just like it. Many of these stars have their own systems of planets, moons, asteroids, and comets.

The Sun was born in a vast cloud of gas and dust around 5 billion years ago. Indeed, these vast nebulae are the birth places of all stars. Over a period of many millions of years, this gas and dust began to fall into a common center under the force of its own gravity.

At the center, an ever growing body of mass was forming. As the matter fell inward, it generated a tremendous amount of heat and pressure. As it grew, the baby Sun became hotter and hotter. Eventually, when it reached a temperature of around 1 million degrees, its core ignited, causing it to begin nuclear fusion.

When this happened, the Sun began producing its own light, heat, and energy.

What is Thermonuclear Fusion?

Thermonuclear fusion is the process in which a star produce its light, heat, and energy. This happens at the core of the star. The core is superheated to millions of degrees. This heat travels towards the surface and radiates out into the universe. Through this thermonuclear process, stars "burn" a fuel known as hydrogen. The result is that they create another type of fuel known as helium. However, stars do not burn in the same way that a fire does, because stars are not on fire.

Convection

Heat rises, while cooler gas falls. Have you ever noticed that your basement is always much cooler than upstairs. The same laws of physics apply within stars. Because heat rises while cooler gases fall, the gas within a star is constantly rising and falling. This creates massive streams of circular motion within the star. This is called convection.

As the gases near the core of the Sun are heated, they begin to rise towards the surface. As they do so, they cool somewhat. Eventually they become cool enough that they begin to sink back down towards the core. It can take an atom millions of years to complete one complete cycle around a convection stream. As a result of this process, the temperature on the surface of the Sun is around 10,000 degrees Fahrenheit, which is much cooler than its superheated core.

Sun Spots

We don't often think of the Sun as having cooler areas on its surface. The Sun is far too hot for an astronaut to ever visit, but there are areas which are slightly cooler than others. These areas are known as sun spots. Sun spots are still very hot. However, because they are slightly cooler than the rest of the surface of the Sun, they appear slightly darker in color. The gravitational forces in Sun spots are also stronger than the other hotter areas. Of course, you cannot look directly at the Sun to see these spots because you would damage your eyes. Astronomers have to use special telescopes with filters and other instruments to be able to see the cooler spots on the surface of the Sun.

Sun spots come and go on a regular basis. At times, there are very few, if any sun spots. At other times there are far more. They generally increase in intensity and then decrease over a period of 11 years. This 11 year cycle is known as the Saros Cycle.  To learn more, click here.

Solar Flares

During periods of high solar activity, the Sun commonly releases massive amounts of gas and plasma into its atmosphere. These ejections are known as solar flares. Some solar flares can be truly massive, and contain impressive power. On occasion, these more powerful flares can even cause satellites orbiting the Earth to malfunction. They can also interact with Earth's magnetic field to create impressive and beautiful light shows known as the Northern and Southern lights. In the northern hemisphere, these lights are commonly known as the Aurora Borealis.

Solar Winds

As the Sun burns hydrogen at its core, it releases vast amounts of atomic particles, or pieces of atoms, into outer space. These atomic particles along with the Sun's radiation create a sort of wind, known as the solar wind.

This wind blows particles outward in all directions from the Sun. Even as you read this, there are atomic particles which are traveling from the Sun towards you. Often, particles pass right through your body without you ever realizing it.

Eventually this wind reaches out beyond the Solar System and begins to mix with the winds from other stars. The bubble around the Sun where the solar winds are still strong enough to blow outward is known as the heliosphere (note the Greek name Helios). The area of space where the winds are too weak to continue pushing outward and instead begin to mix with the winds of other stars is known as the interstellar medium.

The Sun's Family

The Sun is by far the largest object in the Solar System. 98% of all matter within the Solar System is found within the Sun. This means that all the planets, moons, asteroids, minor planets, comets, gas, and dust would all combine to make up only 2% of all the matter in the Solar System. The Sun is so large that the Earth could easily fit inside the Sun a million times.
Because the Sun is so large compared to everything else, it is easily able to hold on to the rest of the matter, causing everything else to orbit around it.

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Light from the Sun can reach the Earth in only 8 minutes! This is called the speed of light. The Sun is nearly 93 million miles (approx 145 million km) from Earth.

  

What are asteroids? An asteroid is a large rock in outer space. Some, like Ceres, can be very large, while others are as small as a grain of sand. Due to their smaller size, asteroids do not have enough gravity to pull themselves into the shape of a ball.  Astronomers group asteroids into different categories based on the way they reflect sunlight. The asteroid belt is divided into an inner belt and an outer belt. The inner belt, which is made up of asteroids that are within 250 million miles (402 million km) of the Sun, contains asteroids that are made of metals. The outer belt, which includes asteroids 250 million miles (402 million km) beyond the Sun, consists of rocky asteroids. These asteroids appear darker than the asteroids of the inner belt, and are rich in carbon. Where did the Asteroid Belt come from?

Asteroids are left over materials from the formation of the Solar System.  These materials were never incorporated into a planet because of their proximity to Jupiter's strong gravity.

omets
Among the most brilliant and most rare objects in the night sky. These soaring beacons with their beautiful tails come from the outer realms of the Solar System

Wishing on a meteorite!

                                                           Written for the KidsKnowIt Network by:
                                                                               Gemma Lavender, MPhys, FRAS
                                               
    Image: NASA

You have probably heard of a shooting or falling star, but have you ever seen one? If you have ever spent any amount of time looking up at the night sky, then you probably have - a flash of light streaking high above through the darkness for just a moment, disappearing just as quickly as it appeared - sometimes so quick that you cannot be sure if you have really seen something or imagined it. You might think that your eyes are playing tricks on you, but shooting stars are definitely real! Your parents may have told you to quickly make a wish on a shooting star before it vanishes - what will your next wish be when you get to see one?

Here’s another question for you, a little bit harder this time: do you know what a shooting star is? Their names are a little misleading and this causes some people to think that these fast moving trails of light really are stars that have fallen out of the sky. However, this is not true. Our Sun is a star, our closest star, and the other stars are many many miles away (it would take more than your lifetime to travel to them!) and since they are much bigger than a shooting star, they are certainly not responsible, so we can count them out. If you are still not sure of the answer, then you might be surprised to learn that shooting stars are just tiny bits of dust entering the Earth’s atmosphere from space. Tiny particles, like grains of sand or pebbles on a beach, like to crash into the atmosphere at amazingly fast speeds - some faster than a car travelling at his highest speed along the motorway! But don’t worry - they are not big enough to harm you! If you pick up a stone from the beach, however, you will find that a fast moving pebble does not quite look the same as a shooting star, no matter how hard you throw it. This is because the light that you see is the heat of the air around them as they fly into the atmosphere and burn up.

 

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Image: NASA Sometimes something a little bigger than a pebble will shoot through the atmosphere and we seem them as fireballs - if you are lucky enough to see one of these then you might see flames shooting from it! But don’t worry, fireballs are not dangerous - like shooting stars, they are high above us.

The point in the sky where a meteor shower originates is called the radiant point.  It is much like the center of a bicycle wheel with the meteors radiating outward from the center.  During a meteor shower, the radiant point will move across the sky as the Earth continues to rotate.  Keep reading below to see all the different meteor showers that occur during the year, and learn how the showers got their names.

Occasionally, however, the piece of rock can be big enough so that it does not all burn up while entering the atmosphere and it will hit the ground. We call these meteorites (while they are flying through the atmosphere as shooting stars we call them meteors, and while they are in space we call them meteoroids - it is important to remember the difference!). A whopping 38,000 meteorites have been found on Earth so far, from all over the world, but most are found in the hot desert or in freezing cold Antarctica. You may have heard stories of someone you know that has found a meteorite or maybe you have even found one yourself! If you have never had the chance to touch or see a meteorite, then you might not know that these space rocks are quite different to the ones that you are likely to find in your backyard, but not in the way that you might think.

Image courtesy of Lunar and Planetary Institute
This map shows some of the locations in Antartica where many meteorites have been found.

There are three main types of meteorites: stony, iron and stony-iron. A lot of them have been smashed off from very large chunks of rock, called asteroids, in collisions before eventually finding their way to our planet. Iron meteorites, for example, are bits of metal iron cores of large asteroids that were once hot enough to have melted, causing all of their iron to sink to the centre. Stony meteorites look most like the stones that you find on Earth and come from the outer layer of asteroids, whereas stony-iron meteorites are a mixture of the two.

Image courtesy of NASA Johnson Space Center
This meteorite came from the moon.

Comets and asteroids are leftover debris from the when the planets were being built in the Solar System. Just like asteroids, comets make falling stars, but rather than seeing one of them every so often (that are easy to miss!), there is a shower of them - astronomers call these meteor showers and they are made when the Earth moves through the tail of a comet that has been left behind after one of these icy and dusty bodies have swooped past us. You can usually see at least a few meteors during a shower, but on a particularly good show, you can sometimes see hundreds of shooting stars per hour - you can be sure not to miss one then! The best meteor showers are the Quadrantids that are at their best on the 3rd January every year, the Lyrids that are at their best on 22nd April, the famous Perseids on 12th August, the Orionids on 22nd October, the Leonids on 17th November and the Geminids on 14th December. The Geminids, it is thought, are actually dust from an asteroid called Phaethon rather than a comet - and it has been shown that Phaethon was originally part of the second biggest asteroid Pallas, but was smashed off in a mighty collision with another asteroid billions of years ago. Meteor showers are named after the constellation that they appear to be falling from. For example, the Geminids will be shooting away from the constellation, Gemini (The Twins), whereas the Perseids are from Perseus (The Hero). Why don’t you grab a map of the constellations and, with your friends, see if you can find them in the night sky before the meteor showers start?

So, ready to go meteor spotting? Check out the box, How to watch a meteor shower, to find out how!

Image: NASA

How to watch a meteor shower Watching a meteor shower can be one of the most enjoyable things about observing the night sky, waiting with tense excitement to see the next shooting star. The best meteor shower is the Perseids - not just because it has the most meteors (although it does have as many as 100 per hour) - but because you can sit out in the garden during the warm summer night to watch them, rather than having to wrap up in your scarf, bobble hat and wooly mittens during the middle of winter, as you would have to for watching the Geminids in December!   Image: NASA   For the best meteor viewing, it is best to find a dark corner of your garden or from wherever you are observing them. Give time for your eyes to get used to the darkness, and use a red light flashlight rather than a normal flashlight, so that you do not ruin your night vision when looking at maps of the night sky. If you do not have a red light flashlight, then you can just cellotape some red see-through paper over a normal flashlight - it works just as well! To avoid going back inside, bring a water bottle and some snacks out into the garden with you. Make sure that you wrap up warm - even in August for the Perseids, it can still get chilly late at night. Remember that a hat is essential, as your body loses much of its heat through your head. Now, you have probably found that when looking at the stars that straining your neck to look up all the time can quickly become uncomfortable. For meteor watching, a deck chair is ideal - you are angled comfortably so you do not have to strain your neck. Image: NASA Simply watching for meteors and counting up how many you see in your head is fun, but if you want to be a proper scientist then you need to record your results, as you would during a real science experiment. With a clipboard, pen and paper, write down the time that you see each meteor, in which direction the meteor comes from, its colour (if you can see any colour!), and how bright it was compared to other stars in the constellations that surround it. Remember that a star map will be able to help you with how bright certain stars are in a constellation.                                   The meteorites you see during a meteor shower might appear to be very close, but did you know that those tiny particles of burning space debris are actually about 30 to 40 miles (48 to 64km) above Earth's surface?  Pretty amazing that you are able to see such a tiny piece of space dust from so far away!

So you’ve spent some time out in the garden, watching and recording meteors. What do you do with your results then? Some scientists can use your results, such as those at astronomical associations, and they will look for trends in the meteor shower - for example, were they more or less active than in previous years? If so, why? If you are unsure of who to contact, you should ask your teacher or parents to help you. Who knew that by watching a meteor shower and reporting what you see could allow you to contribute to real life science! How exciting is that?! Near the Grand Canyon in Arizona is Meteor Crater (above).  It was formed about 50,000 years ago when a meteor about 30 meters wide and weighing 100,000 tons struck the Arizona desert at an estimated speed of 20 kilometers per second (12 miles per second).

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What  are comets? A comet is a small world which scientists sometimes call a planetesimal. They are made out of dust and ice, kind of like a dirty snow ball. Where do they come from? Comets come from two places:  The Kuiper Belt and the Oort Cloud.

Many people think that a comet's tail is always following behind it, but actually the coma, or tail, can either be behind the comet or in front of it. Which way the tail is pointing depends on where the Sun is. That's right, the Sun's heat and radiation produce a wind called the Solar Wind, as a comet gets close to the Sun it begins to melt. The gas and dust that melt off are blown away from the Sun by the solar winds. So if a comet is traveling towards the Sun then the tail will follow behind, but if the comet is traveling away from the Sun the tail will be in front of the comet.

Imagine a place far, far away at the very edge of the Solar System. A place where millions of comets can be seen swishing around in every direction. These icy comets are orbiting the Sun in two different places, both of which are very distant.  One place is called the Oort cloud, and the other is called the Kuiper Belt. 

Why do Comets leave their home in the Oort Cloud or Kuiper Belt?
A comet will spend billions of years in the Kuiper Belt or Oort Cloud.  Sometimes two comets will come very close to each other, or even crash into one another.  When this happens the comets change directions.  Sometimes their new path will bring them into the Inner Solar System.

This is when a comet begins to shine. Up until now the comet has been among millions of others exactly the same, but as they approach the warmer Inner Solar System they begin to melt leaving behind magnificent tails.

Unfortunately, comets don't live very long once they enter the warmer part of the Solar System. Just like a snowman melts in the summer, comets melt in the Inner Solar System.   Although it is the most glorious part of their lives, traveling through the Inner Solar System eventually kills them.  After several thousand years they melt down to a little bit of ice and dust, not nearly enough to leave a tail. Some even melt away completely.

To learn about Halley's comet, click here.

Would it be safe to fly through the tail of a comet?
Unlike a recent blockbuster movie showing a space ship flying past giant rocks the size of houses, a comet's tail is actually quite safe. The only thing that would hit your ship would be microscopic pieces of dust.

Enjoy these pictures of real comets.

How many asteroids are there?

26 very large asteroids have been discovered, which is probably most of the big ones. But there are still millions of smaller ones that we have yet to see because they are too tiny, only a mile or so across.

If we stuck all the asteroids together, how big would the new planet be?
If all the materials of all the asteroids were squashed up into one planet it would be smaller than our moon.

While most asteroids can be found in the Asteroid Belt, others are in strange orbits straying far from home. It is currently believed that at least 5000 asteroids cross the Earth's orbit, some coming very close. Don't worry though, asteroids and comets only hit the Earth every 100 million years or so.

 

Quaoar
Quaoar is the largest known non-planet object in the Solar System.  It is one tenth the size of the Earth, and is larger than all other asteroids put together.	No picture currently available

Ceres
For many years Ceres was thought to be the biggest asteroid in the Solar System. It is about 600 miles wide and contains about 25% of the mass of all the asteroids combined.  However, in the summer of 2001 scientists discovered an even bigger asteroid orbiting the Sun near Pluto.	No picture currently available

2001 KX76 The New Asteroid King
On August 23, 2001, astronomers announced the discovery of a new asteroid.  The new asteroid is even bigger than Ceres, which for over two hundred years had been thought to be the largest asteroid in the Solar System.  It was discovered looking at old photographs taken of the sky.

Ida and Dactyl
Ida is a neat little asteroid about 36 miles wide. It is unique because it has its own little moon called Dactyl.	Ida Dactyl