Why Does The Sun Shine

Sun

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.

Asteroids

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.

Comets

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.

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. magine 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.

More to Learn

Below are the names of the planets in the Solar system, frrom the nearest to the Sun to the farthest. The words given in the brackets would probably help us to remember the order of the planets better.
1. Mercury ( My )
2. Venus    (Very ）
3. Earth     ( Excellent )
4. Mars      ( Mother )
5. Jupiter    ( Just )
6. Saturn    ( Served )
7. Uranus   ( Us )
8. Neptune ( Nine )
9. Pluto      ( Puddings )

The Planets Song

Let Us Do This

1. Think creatively and design ten labels for the Sun and the nine planets.
2. Select ten pupils to represent the Sun and the nine planets.
3. Each pupils pins on a label.
4. Using powdered chalk, draw nine concentric circles in the school field.
5. Take up positions of the planets as shown in the diagram.
6. Each pupil moves like a planet round the Sun.
(a) Name the planets which are closer to the Sun than Earth.
(b) Draw and show the relative distance of the planets in the Solar Systems in your Science Journal.

Pluto and the other dwarf planets

Pluto used to be classed as a planet of the solar system, but is now considered to be a dwarf planet, and a part of the Kuiper belt. The Kuiper belt is a vast collection of dwarf planets, asteroids, rocks, ice and dust that circle the sun, that extends for millions of miles beyond Neptune, on the outskirts of the solar system.

As of mid-2008, five smaller objects are classified as dwarf planets, all but the first of which orbit beyond Neptune. These are:


Ceres (415,000,000 km from the sun)
Pluto (5,906,000,000 km, from the sun, formerly classified as the ninth planet)
Haumea (6,450,000,000 km from the sun)
Makemake (6,850,000,000 km from the sun)
Eris (10,100,000,000 km from the sun)

Neptune

Neptune is the outermost planet of the solar system. It is slightly smaller than Uranus. Neptune has also been visited by only one spacecraft, Voyager 2, on Aug 25 1989.

Neptune has a mark on it that looks very similar to Jupiter's great spot. Just like Jupiter, this is caused by violent storms.

The weather is very extreme on Neptune - the wind on Neptune is the strongest on any planet, and blows at 1,300 miles per hour - as fast as a jet fighter plane.

Neptune is 4,500,000,000 km away from the sun.

Uranus

Uranus is the lightest of the outer planets, a type of gas giant that some scientists call an ice giant. As you can imagine from this nickname its atmosphere is very cold - the coldest in the solar system. The wind on Uranus can blow at over 500 miles per hour!

It was discovered by William Herschel, a famous astronomer, while systematically searching the sky with his telescope on March 13, 1781.

Uranus has been visited by only one spacecraft, Voyager 2 on Jan 24 1986. The picture on the left is an enhanced image of Uranus that was beamed back to Earth by Voyager 2.

Uranus is 2,880,000,000 km away from the sun.

Saturn - the ringed planet

Saturn is distinguished by its extensive ring system, but otherwise has several similarities to Jupiter. They are both gas giants. Saturn has at least sixty known satellites; two of which, Titan and Enceladus, show signs of geological activity, though they are largely made of ice.

Saturn was first visited by NASA's Pioneer 11 in 1979 and later by Voyager 1 and Voyager 2. Cassini (a joint NASA / ESA project) arrived on July 1, 2004 and is still in orbit now.

Saturn's rings are extraordinarily thin: though they're 250,000 km or more in diameter they're less than one kilometre thick. The ring particles seem to be composed primarily of water and ice, but they may also include rocky particles with icy coatings.

Saturn is 1,430,000,000 km away from the sun.

Jupiter

Jupiter is the biggest planet in the solar system. It is 2.5 times the mass of all the other planets of the solar system put together! It is a gas giant, rather than a terrestrial planet, and is made largely of hydrogen and helium.

The large spot on Jupiter is actually a storm that has been raging for several hundred years!

Jupiter was first visited by Pioneer 10 in 1973 and later by Pioneer 11, Voyager 1, Voyager 2 and Ulysses. The unmanned spacecraft Galileo orbited Jupiter for eight years. In 2003 Galileo was crashed deliberately into Jupiter, to stop it from impacting on Europa, one of Jupiters moons that scientists believe may harbour some basic form of life.

Jupiter is 779,000,000 km away from the sun.

Mars - the red planet

Mars is smaller than both Earth and Venus. The first spacecraft to visit Mars was Mariner 4 in 1965. Several others followed, most recently in 2008, when Phoenix landed in the northern plains to search for water. Three Mars orbiters (Mars Reconnaissance Orbiter, Mars Odyssey, and Mars Express) are also currently at work studying Mars.

NASA has landed several unmanned robotic probes on Mars, most recently two remote controlled car-like robots called Mars Rovers. These probes allow NASA scientists to explore the planet, take pictures, analyse soil and conduct experiments. The picture on the left is of one of the Mars Rovers on the surface of Mars.

Mars is named after the Greek God of War. It is sometimes also called the red planet, because most of its surface is covered in reddish rocks, dust and soil.

Mars is 228,000,000 km away from the sun.

Earth

Earth is the largest and densest of the four inner planets, the only one known to have current geological activity, like earthquakes and volcanoes. It is the only planet known to have life. Its liquid hydrosphere (oceans and seas) is unique among the terrestrial planets.

Earth's atmosphere is radically different from those of the other planets, having been altered by the presence of life so it now contains 21% oxygen - which humans need to be able to breathe!

It has one natural satellite, the Moon, which is the only large satellite of a terrestrial planet in the Solar System.

The Earth is 150,000,000 km from the sun.

Venus

Venus

Venus is a very similar size to the Earth, and like Earth, is made of a thick silicate mantle around an iron core. It has a substantial atmosphere and evidence of internal geological activity. Venus is probably the planet that is most similar to Earth in many ways, although it is much drier than Earth and its atmosphere is ninety times as dense.

It is the hottest planet in the solar system, with surface temperatures over 400 °C. This is thought to be because of the amount of greenhouse gases in its atmosphere.

Venus is named after the Greek Goddess of Love and Beauty.

Venus is 108,000,000 km away from the sun.

Mercury

Mercury is the closest planet to the Sun, and the smallest planet of the solar system. Mercury has been visited by two unmanned NASA space probes, Mariner 10 and Messenger. The unmanned Messenger proble was launched by NASA in 2004 and will begin to orbit Mercury in 2011 after several flybys.

The picture on the left is a picture of Mercury that was taken by Messenger in 2008, and transmitted back to earth for scientists to study.

Mercury is 57,900,000 km away from the sun.

The Solar System

What is the solar system?

The Solar System is made up of the Sun and the celestial objects that are bound to it by its gravity: the eight planets and five dwarf planets, their 173 known moons, and billions of small bodies, such as asteroids, icy kuiper belt objects, comets, meteoroids, and interplanetary dust.

Although the farthest planet is over four billion kilometers away from the earth, all eight planets can be seen in the night sky, using a telescope or binoculars - as long as you know where to look