In 1962, two American policemen in the little town of Manitowoc on the shores of Lake Michigan found a 9 kg (20lb) chunk of red-hot metal embedded in the street. It was the remains of the Russian satellite, Sputnik 4. Quite apart from the man-made junk from old spacecraft, There are also various natural object, mostly lumps of rock and metal, that approach the Earth from outer space from time to time. Most are spectacular but harmless, burning a blazing trail through the sky, but others threaten the continued existence of life on Earth.
Impact Earth
The Earth is constantly bombarded by debris from space. Most is small enough to burn up as it enters the Earth's protective atmosphere. But from time to time, larger object get through. Some explode before they reach the Earth's surface. Others collide with the Earth and puncture is crust.
Saturday, November 24, 2007
The first man on the Moon
In 1966, the unmanned Soviet space probe Luna 9 landed on the Moon. But it was not until three years later that the first human set foot there. On July 20, 1969, Neil Armstrong of the Apollo 11 mission landed in an area of the Moon called the Sea of Tranquillity. Armstrong descended from the lunar module, claiming 'one small step for man one giant leap for mankind'. Thousand of samples of Moon rock and soil were collected, and hundreds of photographs taken, before Apollo 11's three-man crew returned safely to Earth. In all, only 12 people have so far set foot on the Moon.
In 1966, the unmanned Soviet space probe Luna 9 landed on the Moon. But it was not until three years later that the first human set foot there. On July 20, 1969, Neil Armstrong of the Apollo 11 mission landed in an area of the Moon called the Sea of Tranquillity. Armstrong descended from the lunar module, claiming 'one small step for man one giant leap for mankind'. Thousand of samples of Moon rock and soil were collected, and hundreds of photographs taken, before Apollo 11's three-man crew returned safely to Earth. In all, only 12 people have so far set foot on the Moon.
Friday, November 23, 2007
Could we live on the Moon?
The Moon has no atmosphere to protect it from the Sun's rays. It is baked during the day and frozen at night, as the day's warmth escapes into space. To survive on the Moon, humans need spacesuits for insulation and air. Food and water have to be brought from Earth. It is possible that water in form of ice is already present at the Moon's poles. If it could be melted, algae and bacteria brought from Earth could then be grown as food.
Other moons
All the planets in the Solar System, except Mercury and Venus, have at least one moon, and Saturn has 18 or more. The smallest of Saturn's moons, Pan, is only 20 km (12 miles) in diameter, and the biggest, Titan, is 5150 km (3200 miles), which makes it larger than the planet Mercury. It also has an atmosphere with a pressure ten times greater than the Earth's. This atmosphere protects Titan from bombardment by meteorites. The Cassini spacecraft, launched in 1997, will reach Saturn in 2004 and send a probe to sample Titan's surface.
The Moon has no atmosphere to protect it from the Sun's rays. It is baked during the day and frozen at night, as the day's warmth escapes into space. To survive on the Moon, humans need spacesuits for insulation and air. Food and water have to be brought from Earth. It is possible that water in form of ice is already present at the Moon's poles. If it could be melted, algae and bacteria brought from Earth could then be grown as food.
Other moons
All the planets in the Solar System, except Mercury and Venus, have at least one moon, and Saturn has 18 or more. The smallest of Saturn's moons, Pan, is only 20 km (12 miles) in diameter, and the biggest, Titan, is 5150 km (3200 miles), which makes it larger than the planet Mercury. It also has an atmosphere with a pressure ten times greater than the Earth's. This atmosphere protects Titan from bombardment by meteorites. The Cassini spacecraft, launched in 1997, will reach Saturn in 2004 and send a probe to sample Titan's surface.
Moon base
In March 1998, instruments on board the American lunar probe Prospector detected hydrogen at the Moon's poles, which indicates that there may be up to 300 million tonnes of water frozen into the Moon's surface. If this is the case, the a permanent space station on the Moon could become possible, making the exploration of deep space easier. The station would use solar panels of collecting light energy from the Sun and providing power and heat. Because of the Moon's low gravity, spacecraft taking off from the Moon towards distant parts of the Solar System would require less energy and fuel.
Moon's gravity (Astronaut Atletics)
The Moon's gravity is only a sixth as strong as that of the Earth. This means that, on the Moon, the world high-jump champion could leap nearly 15 m (48 ft), and the long-jumo record would be about 54 m (180 ft). But having to wear a spacesuit might limit an astronaut athlete's performance.
In March 1998, instruments on board the American lunar probe Prospector detected hydrogen at the Moon's poles, which indicates that there may be up to 300 million tonnes of water frozen into the Moon's surface. If this is the case, the a permanent space station on the Moon could become possible, making the exploration of deep space easier. The station would use solar panels of collecting light energy from the Sun and providing power and heat. Because of the Moon's low gravity, spacecraft taking off from the Moon towards distant parts of the Solar System would require less energy and fuel.
Moon's gravity (Astronaut Atletics)
The Moon's gravity is only a sixth as strong as that of the Earth. This means that, on the Moon, the world high-jump champion could leap nearly 15 m (48 ft), and the long-jumo record would be about 54 m (180 ft). But having to wear a spacesuit might limit an astronaut athlete's performance.
Thursday, November 22, 2007
MAN ON THE MOON
The Earth has only one moon orbiting around it. Our Moon is a dry and dusty place, pockmarked with craters. Once, there may have been life there, but no traces have yet been found. The only way that the Moon might support life in the future is if it comes from Earth, a manned lunar space station would provide a useful launch site for exploring our Solar System and beyond. But life could only be sustained if there is water on the Moon.
How was the Moon formed?
The Earth and the Moon are locked together in their joint orbit of the Sun, and they are made from rock of the same age, about 4.5 billion years old. They are so similar that it is likely the Moon was originally part of the Earth, but was torn from it when the Earth collided with another planet. The Earth surface was torn apart in the collision, and gas, molten lava and rocks from the Earth's interior were thrown into space. These cooled and condensed into a single ball with a hard crust orbiting the Earth as our Moon.
How was the Moon formed?
The Earth and the Moon are locked together in their joint orbit of the Sun, and they are made from rock of the same age, about 4.5 billion years old. They are so similar that it is likely the Moon was originally part of the Earth, but was torn from it when the Earth collided with another planet. The Earth surface was torn apart in the collision, and gas, molten lava and rocks from the Earth's interior were thrown into space. These cooled and condensed into a single ball with a hard crust orbiting the Earth as our Moon.
Is there life on other planets?
Scientists reckon that the chances of life somewhere else in the Universe are high enough to spend hundred of millions of dollars searching for it, but they are more doubtful about extraterrestrial life in our own Solar System. Life depends on two-dozen chemical elements, of which carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus are the most important. For life to continue, light and warmth are needed. Mars has the right chemical ingredients and may once have had the right conditions. A 4.5 billion-year-old meteorite from Mars, found in Antarctica, contains what some scientists think is a fossilised microbe that may have lived on the 'Red Planet'. Conditions now, including subzero temperatures, are not suitable for life on Mars. They may, however, be kinder on Europa, one of Jupiter's moons. Satellites have photographed ancient river valleys on Europa, and they may still be water below its ice cover.
Tight squeeze
In space, people grow larger, by up to 5 cm (2 in), because there is no gravity to pull their body parts downwards. This increase in size can cause problems. On one Shuttle mission, the astronauts found they had grown so much that they could hardly squeeze into a tigh-fitting chair that they wre supposed to sit in for an important experiment.
Scientists reckon that the chances of life somewhere else in the Universe are high enough to spend hundred of millions of dollars searching for it, but they are more doubtful about extraterrestrial life in our own Solar System. Life depends on two-dozen chemical elements, of which carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus are the most important. For life to continue, light and warmth are needed. Mars has the right chemical ingredients and may once have had the right conditions. A 4.5 billion-year-old meteorite from Mars, found in Antarctica, contains what some scientists think is a fossilised microbe that may have lived on the 'Red Planet'. Conditions now, including subzero temperatures, are not suitable for life on Mars. They may, however, be kinder on Europa, one of Jupiter's moons. Satellites have photographed ancient river valleys on Europa, and they may still be water below its ice cover.
Tight squeeze
In space, people grow larger, by up to 5 cm (2 in), because there is no gravity to pull their body parts downwards. This increase in size can cause problems. On one Shuttle mission, the astronauts found they had grown so much that they could hardly squeeze into a tigh-fitting chair that they wre supposed to sit in for an important experiment.
Wednesday, November 21, 2007
Formation of the planets
The planets are all different. Some probably formed mainly from colliding specks of dust, and others from collapsing blobs of gas and dust.
How was the Earth formed?
Scientists believe that the Earth formed from dust particles that clumped together to form lumps, which collided and formed larger lumps and clusters, gradually building into a planet. Temperatures rose to more than 5000 Celsius (9000 Fahrenheit), enough to melt the Earth into a churning cauldron. As he Earth started to cool, the surface formed a rocky crust. But deep inside the Earth, temperature are still 4500 Celsius (8100 Fahrenheit) and the rocks are molten, rising to the surface most spectacularly when a volcano erupts.
The planets are all different. Some probably formed mainly from colliding specks of dust, and others from collapsing blobs of gas and dust.
How was the Earth formed?
Scientists believe that the Earth formed from dust particles that clumped together to form lumps, which collided and formed larger lumps and clusters, gradually building into a planet. Temperatures rose to more than 5000 Celsius (9000 Fahrenheit), enough to melt the Earth into a churning cauldron. As he Earth started to cool, the surface formed a rocky crust. But deep inside the Earth, temperature are still 4500 Celsius (8100 Fahrenheit) and the rocks are molten, rising to the surface most spectacularly when a volcano erupts.
The beginnings of Earth making
Particles of dust and rock collided and clumped together to form the beginnings of the Earth
4.6 - 4.2 billion years ago :
Meteorites crash into the Earth's liquid surface. The heat from these collisions caused the rock in the growing planet to melt. Heavier metals, such as iron, sank towards the core, while lighter materials rose to the surface.
4.2 - 3.8 billion years ago :
As the Earth began to cool, its surface congealed to form a crust over the semiliquid layers beneath. Heat in the Earth's centre created huge volacanoes that poured out lava onto the surface. Meteorites continued to bombard the planet.
3.8 - 2.5 billion years ago :
The hot gases and water vapour that spewed from the Earth's volcanoes cooled and condensed into clouds - the Earth's first atmosphere. There were thunderstorms and torrential rains. Water - in the form of rivers, lakes and oceans - appeared for the first time. Primitive bacteria - the first signs of life - appeared.
2.5 billion - 600 million years ago :
The crust split into mobile plates that began to resemble the continent
Particles of dust and rock collided and clumped together to form the beginnings of the Earth
4.6 - 4.2 billion years ago :
Meteorites crash into the Earth's liquid surface. The heat from these collisions caused the rock in the growing planet to melt. Heavier metals, such as iron, sank towards the core, while lighter materials rose to the surface.
4.2 - 3.8 billion years ago :
As the Earth began to cool, its surface congealed to form a crust over the semiliquid layers beneath. Heat in the Earth's centre created huge volacanoes that poured out lava onto the surface. Meteorites continued to bombard the planet.
3.8 - 2.5 billion years ago :
The hot gases and water vapour that spewed from the Earth's volcanoes cooled and condensed into clouds - the Earth's first atmosphere. There were thunderstorms and torrential rains. Water - in the form of rivers, lakes and oceans - appeared for the first time. Primitive bacteria - the first signs of life - appeared.
2.5 billion - 600 million years ago :
The crust split into mobile plates that began to resemble the continent
Tuesday, November 20, 2007
THE BIRTH OF THE PLANETS
The nine planets including, Earth, that form our Solar System are accompanied through space by 63 moons, dozens of comets and hundreds of thousands of lumps of rock that never grew into planets. All of them are held together and guided on their journeys by the Sun, which weighs almost 1000 times as much as the rest of the Solar System put together.
The making of the Earth
After Mercury and Venus, Earth is a third planet from the Sun. This is how geologist think the Earth has developed over the past 4.6 billionb years. The whole planet and a close-up of the surface are shown for each stage.
The making of the Earth
After Mercury and Venus, Earth is a third planet from the Sun. This is how geologist think the Earth has developed over the past 4.6 billionb years. The whole planet and a close-up of the surface are shown for each stage.
Monday, November 19, 2007
Will the Sun last for ever?
Stars last a long time, but not for ever. Our Sun probably reached its peak brightness about 800 million years ago, and should continued to glow with the same intensity for another 1.5 billion years before beginning to fade. Its decline will be a slow process. First, in about 4 billion years, it will grow into a huge red giant star, swallowing the Earth and the inner planets. Then it will collapse into a white dwarf star before cooling and becoming extinct.
Black holes
Massive stars, ten to a hundred times bigger than our Sun, have a life story. They eventually explode, creating a supernova. All the matter from which they are made may collapse back on itself under gravity. Not even light can escape from the collapsing star. It becomes a 'black hole' invisible to even the most powerful telescope.
Stars last a long time, but not for ever. Our Sun probably reached its peak brightness about 800 million years ago, and should continued to glow with the same intensity for another 1.5 billion years before beginning to fade. Its decline will be a slow process. First, in about 4 billion years, it will grow into a huge red giant star, swallowing the Earth and the inner planets. Then it will collapse into a white dwarf star before cooling and becoming extinct.
Black holes
Massive stars, ten to a hundred times bigger than our Sun, have a life story. They eventually explode, creating a supernova. All the matter from which they are made may collapse back on itself under gravity. Not even light can escape from the collapsing star. It becomes a 'black hole' invisible to even the most powerful telescope.
Sunday, November 18, 2007
The star dust inside us all
When our Sun was formed 5 billion years ago, temperature reached 15 million celsius. In a chain of nuclear reactions, atoms of carbon released enormous amounts of energy, creating the building block life. The carbon, hydrogen, nitrogen and oxygen from which our own bodies are made were created billions of years ago. Similar elements can be identified in the fragments of meteorites that have crash-landed on Earth and which are our closet records of conditions in the early Solar System.
When our Sun was formed 5 billion years ago, temperature reached 15 million celsius. In a chain of nuclear reactions, atoms of carbon released enormous amounts of energy, creating the building block life. The carbon, hydrogen, nitrogen and oxygen from which our own bodies are made were created billions of years ago. Similar elements can be identified in the fragments of meteorites that have crash-landed on Earth and which are our closet records of conditions in the early Solar System.
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