DISCOVERY OF THE SOLAR SYSTEM

Discovery of the Solar System

The planets out to Saturn were known to ancient astronomers, who observed the wandering of these objects against the apparently fixed pattern of stars. Venus and Mercury were each identified as single objects despite the difficulty of connecting "evening" and "morning stars". It was also identified that the two non-pointlike objects, the sun and the Moon, moved across the same fixed background.

However knowledge of the nature of these celestial drifters was entirely speculative and largely incorrect.

The nature and structure of the solar system were long misperceived, for at least two reasons:


The Earth was considered stationary, and the motion of objects in the sky was therefore taken at face value: the sun was thought to orbit the Earth, for example (This conception of the universe, in which the Earth is at the center, is called the Geocentric model; geos means "Earth" in Greek).
Many solar system objects and phenomena cannot be perceived at all without technical aid.


Over the last several hundred years, conceptual and technological advances have helped humans understand the solar system much better.

The first and most fundamental of the conceptual advances was the Copernican Revolution, which proposed that the planets orbit the sun—models of the solar system with the sun in the center are called heliocentric; helios meaning "Sun" in Greek). Despite the name, the most striking and then-controversial Copernican realization was not that the sun was central but that the Earth was peripheral, orbital: planets had been considered merely points in the sky, but if the Earth itself was a planet, perhaps the other planets were, like Earth, huge solid spheres.

Philosophically, there were a number of objections to heliocentrism:


The natural state of heavy, mineral objects like the Earth was believed to be at rest. The planets were believed to be made of a separate, ephemeral, light substance.
It was believed that the Earth's motion round the Sun would cause the air to fly off the surface.
If the Earth were mobile, astronomers should have been able to observe parallax of the stars, such as the stars appearing to shift in relation to further objects due to the Earth's change in position.


The subsequent invention of the telescope gave the principal technological advance on discovering the solar system, with Galileo's improved version of the telescope rapidly giving benefit in terms of discovering satellites of other planets, especially Jupiter's four major satellites. This showed that all objects in the universe did not orbit the Earth. However, perhaps Galileo's most important discovery was that the planet Venus has phases like the Moon, proving that it must orbit the Sun.

Then, in 1687, Isaac Newton devised his law of universal gravitation which explained the force that both kept the Earth moving through the heavens and also kept the air from flying away.

Finally, in 1838, astronomer Friedrich Wilhelm Bessel successfully measured the parallax of the star 61 Cygni, proving conclusively that the Earth was in motion.

STRUCTURE & LAYOUT OF THE SOLAR SYSTEM

Structure and Layout of the Solar System

The Sun is a main sequence G2 star that contains 99.86% of the system's known mass. Its two largest orbiting bodies, Jupiter and Saturn, account for 91% of the remainder.

In broad terms, the charted regions of the solar system consist of the Sun and its planetary system: the eight bodies in relatively unique orbits commonly called planets or major planets and two belts of smaller objects, which can be called minor planets, planetoids, meteoroids, or planetesimals. Pluto, the ninth planet, is also considered a member of the outer belt, and its status is currently uncertain. Most objects in orbit round the Sun all lie within the same shallow plane, called the ecliptic plane, and orbit in the same direction. Many are in turn orbited by moons, and the largest are encircled by planetary rings of dust and other particles.

The major planets are, in order, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.

Distances within the solar system are measured most often in astronomical units, or AU. One AU is the mean distance between the Earth and the Sun, or 149 598 000 kilometres. Other units in common use include the gigametre (Gm, one million kilometres) and the terametre (Tm, one billion/milliard kilometres).

Pluto is roughly 38 AU (5.9 Tm) from the Sun, while Jupiter lies at roughly 5.2 AU (778 Gm).

WHAT IS SOLAR TTHE SYSTEM

What is Solar system?

The solar system comprises the EARTH's SUN and the RETINUE of celestial objects gravitationally bound to it. Traditionally, this is said to consist of the Sun, nine planets and their 158 currently known moons; however, a large number of other objects, including asteroids, meteoroids, planetoids, comets, and interplanetary dust, orbit the Sun as well. Astronomers are debating over the presence of a tenth planet.

Although the term "solar system" is frequently applied to other star systems and the planetary systems which may comprise them, it should strictly refer to Earth's system specifically: the word "SOLAR" is derived from the Sun's Latin name, SOL, and thus the term sometimes appears as Solar System.

AGE AND ORIGIN OF THE SOLAR SYSTEM

Age and Origin of the Solar System

Using radiometric dating, scientists can estimate that the solar system is 4.6 billion years old.

The oldest rocks on Earth are approximately 3.9 billion years old. Rocks this old are rare, as the Earth is constantly being resurfaced. To estimate the age of the solar system scientists must use meteorites, which were formed during the early condensation of the solar nebula.

The oldest meteorites are found to have an age of 4.6 billion years, hence the solar system must be at least 4.6 billion years old.

WHICH IS THE RED PLANET

Mars is often called the red planet. the ground there is covered in dusty red soil,which get swept up by the wind to make pink clouds.the rock on mars have lost of iron in them,and iron goes red when it rusts.a better name for mars might be the rusty planet.

WHAT IS AN ORBIT.

An orbit is the path of a planet around the sun, or a moon around a planet.the planet all have different orbit.mercury is the closest planet to the sun. pluto is usually the farthest way.

HOW OLD IS THE EARTH

Scientist think the earth is about 4,600 million year ago although no one was there to see, they think the moon formed then too.

WHICH IS THE HOTTEST PLANET

Venus is not the closest planet to the sun,but it is the hottest.the temperature there can reach 500 degree celcuis that is about eight times hotter than it gets in the sahara desert,the hottest place on earth.

WHAT IS THE DIFFERENCE BETWEEN STARS AND PLANET

The planets are not as big or as hot as stars,and they cannot make light of their own.they were made from the leftovers of the same gas and dust cloud that gave birth to our star,the sun.

GALAXIES

ASTRONOMERS usually give galaxies numbers instead of names. Only a few have names that tell us what they look like - The Whirlpool, The Sombrero, and The Black Eye

ARE STARS STAR-SHAPED?

No, stars are round, like balls. We give them pointy edges when we draw them because this is what they look like from earth, with their light blinking and twinkling.

HOW MANY STARS ARE THERE?

THERE ARE ABOUT 1000 BILLION STARS IN THE MILKY WAY. THAT IS NEARLY 200 STARS FOR EVERY PERSONS LIVING ON EARTH TODAY.
ALTHOUGH WE CANT SEE ALL OF IT, ASTRONOMERS have worked out how big the universe is and how many stars it has. there are about 100 billion billion stars, in around 100 billion galaxies. It,s hard even to think about so many stars.

WHAT ARE STARS MADE OFF.

Stars aren,t solid like the groung beneath your feet. Instead, they are made of gases like the air around you.
The two main gases in stars are called hydrogen and helium. They are the stars fuel. Stars make heat and light from them.
Some times huge flames-like sheets of glowing gas shoot out from a star. These are called PROMINENCES

WHAT IS A RED GIANT

ALL stars are born, live for a very long time and then die. A red giant is a huge old star.

Stars are been born all the time. The start their lives star-nurseries called CLUSTER.

(1) All stars are born in huge spinning clouds of gas and dust. Our sun was born 4.6 Billion years ago.

(2)The gas and dust come together to make lots of balls, which becomes star cluster

(3)Most stars are like our soon and shine steadily for near ly all their lives.

(4)Towards the end of their lives, stars like our sun swell up and become as much as 100 times bigger. They turn into red giants. Our sun will do this in about 5 billion years time.

(5)When it has used up all its gas fuel, a red giant shrinks down into a white dwarf. It isthen about 10,000 times smaller, but still very hot.

(6)The star cools downand ends its life billion of years letar, as a black dwarf- a cold black cinder.

Stars must have at least eight times as much gas fuel as our sun to end their lives in supernova explosions.

WILL THE SUN EVER GO OUT

One day the sun will use up all its gas fuel and die. But this wont happen in your lifetime, or your childrens, or even your great-great-great grandchildrens. Astronomers think that the sun has enough gas fuel to last for at least another 5 billion years.

HOW MANY PLANETS ARE THERE

Our planets, the earth, has eight neighbours. Together they make a family of nine planets which travel around the sun. We call the sun, and all the space bodies that whirl around it, the solar system. Besides the sun and the planets, the solar system includes MOONS, MINI-PLANETS called ASTEROIDS, and COMETS.

The word PLANET comes from the Greek word PLANETES, which means WANDERER.

COMETS are rather like huge dirty snowballs. Most stay out on the edge of the solar system, but a few travel close to the sun. These comets grow gas and dust tails, millions of killometers long, when the suns heat starts to melt them.



An ORBIT is the path of a planet around the sun, or a moon around a planet. The planets all have different orbits. Mercury is the closet planet to the sun. Pluto is usually the farthest away.

Millions of asteroids orbits the sun, in a belt between Mars and Jupiter. Some are like grains of sand. Others are as big as houses. A few ar the size of England

HOW HOT IS THE SUN

Like all stars, Our sun is a huge ball of super-hot gas. It is hottest in the middle, the temperature there is around 15 million degree celcius. The outside of the sun is a lot cooler tha the middle - only 6000 degree celcius. But this is still 25 times hotter than the hottest kitchen oven.
DARK PATCHES called sunspots come's and go on the face of the sun. They make it look as though it has chickenpox. Sunspots are dark because they are cooler and so give out less light than the rest of the sun.
Most sunspots are larger than the earth. PLANTS and ANIMALS couldnt live without the suns heat and light.
The sun is the only star that is close enough to the earth for us to feel it's heat. The next nearest star to earth is called PROXIMA CENTAUR. Our sun's light take's 8.3 minutes to reach us, but PROXIMA CENTAURs takes 4.3 years.
The sun uses more than 30 million truck loads of fuel every seconds.