Exploring our Solar System

OUR SUN

The Sun is the closest star to Earth and is the center of our solar system. A giant, spinning ball of very hot gas, the Sun is fueled by nuclear fusion reactions. The light from the Sun heats our world and makes life possible. The Sun is also an active star that displays sunspots, solar flares, etc.. These phenomena impact our near-Earth space environment and determine our "space weather." Someday, the hydrogen in the Sun will run out. A long time from now. Our star will puff up. It will eat some planets. Even the Earth! Eventually our Sun will end up as a white dwarf.
The highly rarefied area around the sun, called the corona, extends millions of kilometers into space but is visible only during a total solar eclipse (left). Temperatures in the corona are over 1,000,000 K.


What goes around the Sun:
The first thing to notice is that the solar system is mostly empty space. The planets are very small compared to the space between them. Even the dots on the diagrams above are too big to be in proper scale with respect to the sizes of the orbits.
The orbits of the planets are ellipses with the Sun at one focus, though all except Mercury are very nearly circular.
Mercury, Venus, Earth and Mars are all Rocky planets, inner planets and small planets
Jupiter, Saturn, Uranus and Neptune are gas , outer, giant planets.
The asteroid belt between Mars and Jupiter forms the boundary between the inner solar system and the outer solar system.

Mercury
Very tiny planet, only slightly bigger than Earth’s moon, has a very elliptical orbit. Has no moons.
Venus
It is the brightest object in the sky except for the Sun and the Moon. Venus is sometimes regarded as Earth's sister planet. Venus is only slightly smaller than Earth and their densities and chemical compositions are similar. But it is radically different from Earth. It may be the least hospitable place for life in the solar system.
The pressure of Venus' atmosphere at the surface is very high, composed mostly of carbon dioxide. This dense atmosphere raises Venus' surface temperature by about 400 degrees to over 740 K (hot enough to melt lead). Venus' surface is actually hotter than Mercury's despite being nearly twice as far from the Sun.
Earth
Earth, our home planet, is a beautiful blue and white ball when seen from space. The third planet from the Sun, it is the largest of the inner planets. Earth is the only planet known to support life and to have liquid water at the surface.
Mars
Mars, Earth's outer neighbor, is the fourth planet from the Sun. Mars' bright appearance and reddish color stand out in the night sky. Impressive surface features such as enormous volcanoes and valleys are frequently obscured by huge dust storms. The planet probably got this name due to its red color; Mars is sometimes referred to as the Red Planet. Olympus Mons: the largest mountain in the Solar System rising 24 km (78,000 ft.) above the surrounding plain. Early telescopic observations revealed that Mars has permanent ice caps at both poles.
Jupiter
It is the largest planet in the solar system. When approached from afar, its fantastic striped atmosphere gradually reveals intriguing clouds that move around the planet.
Saturn
Saturn, the sixth planet from the Sun, has the most spectacular set of rings in the solar system.
Uranus
Uranus, the seventh planet from the Sun, has its spin axis almost in the plane of its orbit about the Sun. This produces unusual seasons and also causes unique magnetic and electric field structures.
Neptune
Neptune, the eighth and furthest planet from the Sun, is a very cold place. Its bluish color is caused by small amounts of methane gas in its atmosphere.
Moon
The Moon was first visited by the Soviet spacecraft Luna 2 in 1959. It is the only extraterrestrial body to have been visited by humans. The first landing was on July 20, 1969. The gravitational forces between the Earth and the Moon cause some interesting effects. The most obvious is the tides.


Space Exploration:


In 1942 the German V2 was the first rocket to reach 100km from the Earth’s surface (the boundary of space).The rocket was designed by Wernher Von Braun, who later worked with NASA as the creator of the rockets that went to the moon.

In 1947, the first animals were launched into space. Fruit flies were used to study the effects of space travel on animals, and were chosen because they are more similar to humans than you might imagine!The flies travelled with a supply of corn to eat on the flight.

Albert II, was the first monkey in space. He was a Rhesus monkey, a type of monkey that originally comes from Asia. Albert went into space on 14th June, 1949 in a specially adapted American V2 rocket, that flew to a height of 83 miles from earth.

On 4th October 1957, Russia launched the first satellite into space; Sputnik 1, and the space age had properly begun!Sputnik was the first satellite in orbit around the earth. Today there are over 500 working satellites in space. Sputnik means "Satellite" in Russian.

In November 1957, the Russian space dog Laika became the first animal to orbit the earth.Laika travelled in a spacecraft known as Sputnik 2. Laika means "Barker" in Russian, and her mission helped scientists understand whether people could survive in space.

By 1959 Both American and Russian scientists were in a race to get a spacecraft to the Moon; the Russians made it first.Space-probe Luna 2 crash-landed into the moon at a speed that would kill an astronaut if one had been travelling in it! It was ten more years until a human visited the moon's surface.

On 12th April 1961, Russian Cosmonaut Yuri Gagarin became the first man in space. Gagarin's spacecraft, Vostok 1, completed one orbit of the earth, and landed about two hours after launch.Gagarin had to bail out and land using his parachute, because the Vostok 1 was designed to crash land!

In 1963 US President John F. Kennedy promised the world that the US would land men on the moon before 1970. Before they could risk people's lives, NASA sent a robot spaceship to the moon, to make sure they could land without crashing. It was called Surveyor 1, and it made the first soft landing on the Moon on 30th May 1966.

On 20th July 1969, Neil Armstrong, and then Buzz Aldrin took "one small step" and became the first men on the moon. The first words said on the moon were "the Eagle has landed". Their spaceship, Apollo 11 worked perfectly, flying them 250,000 miles to the moon, and bringing them all the way back safely to earth. Buzz was a childhood nickname - his real name was Edwin!

Two days into its journey to the moon, on 13th April 1970, Apollo 13 suffered an explosion caused by a wiring fault. Using only whatever was on board, NASA scientists and the astronauts on board improvised repairs to bring the crippled spaceship home.The mission was a successful failure: although the crew never walked on the moon at least they made it home alive!

In 1973, Russian space probe Mars 2 explored Mars, the fourth planet of the solar system.The probe was made of two parts. One part stayed in orbit for a year, sending pictures of Mars back to earth. The other was to land and explore the surface of Mars, but it was destroyed when its parachute failed to open.

Until 12th April 1981 all spacecraft were designed to be used only once. The Space Shuttle, was designed to be reused for up to 100 visits to space, in an attempt to make space travel less expensive.With five hugely powerful rocket motors, it can fly at more than 17,000 miles per hour. Six have been built.

On January 28th 1986, tragedy struck. Space Shuttle Challenger exploded shortly after launch, because of a fuel system failure. All seven astronauts on board were killed, and all shuttles were grounded for nearly three years.This shocking accident reminded the world of the dangers of space travel, and the incredible bravery of all astronauts.

In 2003, Space shutter Columbia burst into flames on its return journey, and all its’ crew members were killed. On boars was Kalpana Chawla among others.

In 2000 the first permanent crew moved into the International Space Station (ISS), where crews of astronauts have been living ever since. The ISS is a huge space station for research and space exploration that began construction in 1986 and will not be finished until 2010.

On the 28th April 2001 American millionaire Dennis Tito became the first space tourist when he paid around 20 million dollars for a ride in a Russian Soyuz spacecraft.Dennis spent a week in orbit, most of the time visiting the International Space Station. He had to train for 900 hours just to be a passenger!


Why does an astronaut wear a spacesuit?
Space is a very challenging place to explore. There is no air in space, so there is nothing to breathe. It is very cold, unless the sun is shining onto you - and then, without air to protect you, the rays of the sun would soon burn you!To survive in space you need a suit that protects your body from the heat and cold, and surrounds you with air to breathe. Space suits are pressurised, meaning they are full of air to support your body, which is why they look puffed up. A space suit is like a tiny spaceship for one. It is a very complicated machine, with air conditioning, heating, air to breathe and water to drink. It even has a built in toilet!Some space suits attach to a rocket powered backpack, which allows the astronaut wearing it to fly around in space.