tag:blogger.com,1999:blog-72693496437148351972024-03-09T02:15:00.711+08:00PLANET EARTHGet all information about our planet earth and earth natureUnknownnoreply@blogger.comBlogger31125tag:blogger.com,1999:blog-7269349643714835197.post-78204270578756998872008-01-05T19:24:00.000+08:002008-01-05T19:51:25.955+08:00Inside the Earth<span style="font-size:100%;">The centre of the Earth is very hot. This heat produces enough energy to keep the ground under your feet constantly moving as the major land masses, or continents, are carried slowly along on a lower layer of semi-liquid rock. This movement causes the continents to be pulled apart in some places, creating new oceans. In other places, they collide and create mountain ranges.</span><br /><span style="font-size:100%;"></span><br /><strong><span style="font-size:100%;">A shifting world</span></strong><br /><span style="font-size:100%;">Scientists have discovered that around 250 million years ago all of today's main continents were joined together. Animal alive at that time, such as the dinosaurs, were able to move freely across this huge single landmass. By 200 million years ago, it was starting to break up.</span><br /><span style="font-size:100%;"></span><br /><span style="font-size:100%;"><strong>What is the Earth made of?</strong> </span><br /><span style="font-size:100%;">The Earth has an <span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">outer</span> layer of solid rock called the crust (5-60 km/3-37 miles thick), a middle layer of hot, <span class="blsp-spelling-corrected" id="SPELLING_ERROR_1">semi liquid</span> rock called the mantle (2900 km/1800 miles thick), and a very hot liquid centre, the core (3470 km/2160 miles in radius). Inside the Earth, the temperature increase rapidly towards the centre, where it is nearly as hot as on the surface of the Sun.</span><br /><span style="font-size:100%;">The solid crust is broken into pieces, called plates, which float on the mantle. Some plates are covered by oceans, others by the continents. The plates fit together like a jigsaw, and the places where they meet are called plate boundaries. In some places, two plates push together and one slides over the top of the other. Along some boundaries under the ocean, the plates are moving apart.</span><br /><span style="font-size:100%;"></span><br /><strong><span style="font-size:100%;">250 million years ago</span></strong><br /><span style="font-size:100%;">North and South America, Europe, Asia, Australia and the <span class="blsp-spelling-corrected" id="SPELLING_ERROR_2">Antarctic</span> formed one big continent called <em>Pangaea</em>. The rest of the Earth was covered by an ocean called <em><span class="blsp-spelling-error" id="SPELLING_ERROR_3">Panthalassa</span>.</em></span><br /><span style="font-size:100%;"></span><br /><strong><span style="font-size:100%;">135 million years ago</span></strong><br /><span style="font-size:100%;">Africa and South America began to split apart as the South Atlantic opened up. The North Atlantic formed between North America and Europe.</span><br /><br /><span style="font-family:trebuchet ms;font-size:85%;">Tag :<a href="http://technorati.com/tags/Earth" rel="”tag”">Earth inside</a></span><br /><span style="font-family:trebuchet ms;font-size:85%;">Tag :<a href="http://technorati.com/tags/shifting" rel="”tag”">shifting world</a></span><br /><span style="font-family:trebuchet ms;font-size:85%;">Tag :<a href="http://technorati.com/tags/Earth" rel="”tag”">Earth made</a></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-20805009693974306222007-12-26T15:11:00.000+08:002007-12-26T15:22:13.263+08:00<strong><span style="font-family:trebuchet ms;">The power of the Moon</span></strong><br /><span style="font-family:trebuchet ms;">Many animals use the Moon as a clock or compass. Night-flying birds, such as migrating thrushes, time their journeys to navigate by moonlight.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;">The breeding habits of many sea creatures are guided by the Moon. This is because the Moon and Sun cause the movement of the tides. On May and June nights the tides can be exceptionally high, and horseshoe crabs choose this time to lay their eggs in nests in the sand. High tides give the buried eggs some protection from predators.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">Longer Days</span></strong><br /><span style="font-family:trebuchet ms;">Days are getting longer, due to the pull of the Moon and the Sun. As the gravity of these two heavenly bodies forces the tides up and down around the Earth, the movement drags on the spinning Earth, slowing it down. Less than two thousandths of a second is lost every 100 years, but in 200 million years time an Earth day will be 25 hours long.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;font-size:85%;">Tag :<a href="http://technorati.com/tags/moon" rel="”tag”">moon power</a></span><br /><span style="font-family:trebuchet ms;font-size:85%;">Tag :<a href="http://technorati.com/tags/longer" rel="”tag”">longer day</a> </span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-79343533638438761232007-12-14T22:59:00.000+08:002007-12-14T23:09:57.231+08:00<strong><span style="font-family:trebuchet ms;">Why does <span class="blsp-spelling-error" id="SPELLING_ERROR_0">daylength</span> change through the year?</span></strong><br /><span style="font-family:trebuchet ms;">Earth's tilt is responsible for changing <span class="blsp-spelling-error" id="SPELLING_ERROR_1">daylength</span> as well as the changing seasons. In summer, when the North Pole tilts towards the Sun, it is light there 24 hours a day. Everywhere else in the Northern Hemisphere has a relatively long day and short night. In winter, the position is reversed. The North Pole tilts away from the Sun and the Northern Hemisphere has a relatively short number of daylight hours. The same situation occurs in the Southern Hemisphere.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;font-size:85%;">Tag :<a href="http://technorati.com/tags/daylength" rel="”tag”"><span class="blsp-spelling-error" id="SPELLING_ERROR_2">daylength</span></a> </span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-15107308907723381832007-12-05T02:29:00.000+08:002007-12-05T02:36:53.968+08:00<strong><span style="font-family:trebuchet ms;">What is an eclipse?</span></strong><br /><span style="font-family:trebuchet ms;">On rare occasions the Sun, the Moon and the Earth are in line with each other. The Moon blocks the light from the Sun, casting a shadow 160 km (100 miles) wide on the Earth. The affected area is plunged into darkness in what is known as a solar eclipse. Because the Earth and the Moon are on the move, solar eclipses last for only 71/2 minutes.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">Solar eclipse</span></strong><br /><span style="font-family:trebuchet ms;">When the Earth, the Moon and the Sun are in line, the Moon casts a shadow over part of the Earth's surface.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;font-size:85%;">Tag :<a href="http://technorati.com/tags/eclipse" rel="”tag”">eclipse</a></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-91379232123291210862007-11-29T21:40:00.000+08:002007-11-29T21:48:41.644+08:00<strong><span style="font-family:trebuchet ms;">Why does the Moon's face change?</span></strong><br /><span style="font-family:trebuchet ms;">When we look into the sky, the thing that appears to change most from night is the Moon. But the Moon itself does not change shape. What we see is the Sun's light reflected off the Moon (the Moon generates no light of its own),and this reflection changes as the Earth and the Moon move around the Sun. At the beginning, of the lunar month, the new moon, the lit side of the Moon faces away from Earth, so we see nothing. The portion of the Moon that we can see grows, or waxes, first into a thin silver or crescent, then it grows smaller, or wanes, in a reversal of the process.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;">Tag :<a href="http://technorati.com/tags/moon's" rel="”tag”">m<span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">oon's</span> face</a></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-38984482197998146882007-11-28T13:36:00.001+08:002007-11-28T13:46:26.285+08:00<strong><span style="font-family:trebuchet ms;">Earths orbit</span></strong><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;">At March :The spring day in the north is getting longer and warmer, while the spring day in the south is getting shorter and cooler.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;">At June : The top half of the globe, the Northern Hemisphere, is tilted towards the sun and enjoy more of the Sun's light and warmth. While it is summer in the north, it is winter in the south, which is tilted away from the sun.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;">September : The autumn day in the North is getting shorter and cooler, while the spring day in the south is getting longer and warmer.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;">December : The countries of the Northern Hemisphere are tilted away from the Sun and get the least light and warmth. While it is winter in the North, it is summer in the South, which is now tilted towards the Sun. </span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;">Tag :<a href="http://technorati.com/tags/earths" rel="”tag”">earths orbit</a></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-34918684208265139352007-11-27T21:41:00.000+08:002007-11-27T21:52:53.300+08:00SPINNING EARTH<span style="font-family:trebuchet ms;">All the planets in the Solar System spin as they orbit the Sun, but each does so at a different speed. The Earth takes 24 hours to complete a full spin, and it is this that gives us day and night. While a places faces towards the Sun, it has daylight, while it faces away from the Sun, it has night. The planets also take different lengths of time to orbit the Sun, the Earth, for example, takes 365 days , an Earth year. While the Earth orbits the Sun, the Moon orbits the Earth, taking 29 days, a lunar month, to complete a circuit.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">The four seasons</span></strong><br /><span style="font-family:trebuchet ms;">The Earth's axis tilts at an angle of 23.5 degree. This tilt combined with Earth's orbit, gives hot summers and cold winters, and two seasons of change, spring and autumn.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;">Tag :<a href="http://technorati.com/tags/spinning" rel="”tag”">spinning earth</a></span><br /><span style="font-family:trebuchet ms;">Tag :<a href="http://technorati.com/tags/four" rel="”tag”">four seasons</a></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-18066534759608189152007-11-27T13:53:00.000+08:002007-11-27T14:08:54.004+08:00<strong><span style="font-family:trebuchet ms;">The end of the dinosaurs?</span></strong><br /><span style="font-family:trebuchet ms;">About 65 million years ago, something strange happened to the Earth. A 'missile' 10 km (6 miles) wide, through to be an asteroid from outer space, hit the Yucatan peninsular in Mexico. It dug a crater 12 km (7 miles) deep and 100 km (60 miles) wide. The force of the impact blasted molten droplets of rock across the Americans and set of huge firestorms. Tidal waves 1 km (1.2 mile) high crashed along the shores, and a dust cloud blotted out the Sun. The dinosaurs may have died out as a result.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;"><strong>Diamond wall</strong> </span><br /><span style="font-family:trebuchet ms;">The stone walls of the old church in millions of tiny diamonds, the size of specks of dust. These were formed from molten rock, blasted from the Earth's surface when a meteorite crashed onto it 35 million years ago.</span><br /><span style="font-family:Trebuchet MS;"></span><br /><span style="font-family:trebuchet ms;">Tag :<a href="http://technorati.com/tags/dinosaurs" rel="”tag”">dinosaurs died</a></span><br /><span style="font-family:trebuchet ms;">Tag :<a href="http://technorati.com/tags/diamond" rel="”tag”">diamond wall</a></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-34060868644910132932007-11-26T21:39:00.000+08:002007-11-26T21:49:29.144+08:00<strong><span style="font-family:trebuchet ms;">What happens when a meteor hits the Earth?</span></strong><br /><span style="font-family:trebuchet ms;">About 50 tons of meteors enter the Earth's atmosphere every day, mostly dust-sized particles, but sometimes rocks several metres wide. Most of this material is burnt up as it hurtles through the atmosphere at speed of between 32 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">and</span> 95 km/second (20-60 miles/sec), the blaze can be seen from the Earth as 'shooting' or 'falling' stars. Around 500 meteors a year are big enough, more than a centimetre or so wide, to survive the passage through the atmosphere and do it the Earth. At Meteor Crater in Arizona, <span class="blsp-spelling-corrected" id="SPELLING_ERROR_1">United</span> State, a hole 1.2 km (3/4 mile) wide and 170 m (600 ft) deep was blasted out by one such meteor about 20 000 years ago.</span><br /><span style="font-family:Trebuchet MS;"></span><br /><span style="font-family:Trebuchet MS;">Tag :<a href="http://technorati.com/tags/meteor" rel="”tag”">meteor</a></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-44434491557586233052007-11-26T11:49:00.000+08:002007-11-26T11:59:00.957+08:00<strong><span style="font-family:trebuchet ms;">The travel of comets</span></strong><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;">1. High speed from space : A comet speeds through the Earth's atmosphere at up to 20 km/second (12 miles/sec), causing the atmosphere to heat up quickly.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;">2. Explosion in the sky : The comet explodes 9 km (6 miles) above the Earth's surface. The heat vaporises rocks, which rain back down on Earth.</span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;">3. Shock effects : Shock waves from <span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">explosion</span> travel outwards from the centre of the blast. They flatten the trees and other structures. The shock waves also trigger earthquakes and set off fires.</span><br /><span style="font-family:Trebuchet MS;"></span><br /><span style="font-family:Trebuchet MS;">Tag :<a href="http://technorati.com/tags/comets" rel="”tag”">comets travel</a></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-46583396572501902012007-11-25T23:18:00.000+08:002007-11-25T23:36:17.752+08:00<strong><span style="font-family:trebuchet ms;">How <span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">often</span> do comets come near the Earth?</span></strong><br /><span style="font-family:trebuchet ms;">Comets are like dirty snowballs, lumps of rock, ice and gas, that travel around the <span class="blsp-spelling-corrected" id="SPELLING_ERROR_1">Solar</span> System, guided in their orbit by the gravity of the Sun. They reappear in the night sky at regular intervals, at anything between every six years for some and every 2000 years for others, depending on the size of their orbits. Some comets shine spectacularly as they approach the Sun and ice burns off as gas vapour, forming a blazing tail up to 300 million km(200 million miles) long. Halley's comet, which reappears every 76 years, was first <span class="blsp-spelling-corrected" id="SPELLING_ERROR_2">spotted</span> in 239 BC, it was first illustrated in the Bayeux tapestry, which commemorated <span class="blsp-spelling-corrected" id="SPELLING_ERROR_3">the</span> Norman invasion of England, and was photographed most recently on March 13, 1986, by the space probe Giotto.</span> <br /><br />Tag :<a href=http://technorati.com/tags/comets rel=”tag”>comets</a>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-81357060333434720022007-11-25T15:49:00.000+08:002007-11-25T16:01:48.859+08:00<strong><span style="font-family:trebuchet ms;">What are asteroids?</span></strong><br /><span style="font-family:trebuchet ms;">Tens of thousands of rocks, ranging in size from 1.6 km (1 mile) to 1000 km (600 miles) across, are flying about the Solar System. They are called asteroids, and are mostly found in a belt which lies far beyond the Earth, between the orbits of Mars and Jupiter. The Earth (along with the three other inner planets of the Solar System, Mercury, Venus and Mars) is struck by an asteroid every 200 000 years, or so scientists believe. Our Moon, which does not have an atmosphere to protect it from flying objects, is marked with thousands of impact craters.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">Space rock</span></strong><br /><span style="font-family:trebuchet ms;">On its way to Jupiter, the space probe Galileo photographed a stony asteroid called Ida, which is 58 km (36 miles) long and 21 km (13 miles) wide.</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-88644993634848239122007-11-24T21:44:00.000+08:002007-11-24T21:58:18.374+08:00COMETS, METEORS AND ASTEROIDS<span style="font-family:trebuchet ms;">In 1962, two American policemen in the little town of <span class="blsp-spelling-error" id="SPELLING_ERROR_0">Manitowoc</span> 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 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_1">others</span> threaten the continued existence of life on Earth. </span><br /><span style="font-family:trebuchet ms;"></span><br /><span style="font-family:trebuchet ms;"><strong>Impact Earth</strong></span><br /><span style="font-family:trebuchet ms;">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.</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-34376053239904849552007-11-24T07:27:00.000+08:002007-11-24T07:36:08.528+08:00<strong><span style="font-family:trebuchet ms;">The first man on the Moon</span></strong><br /><span style="font-family:trebuchet ms;">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.</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-59535036476543030082007-11-23T23:28:00.000+08:002007-11-23T23:40:00.735+08:00<strong><span style="font-family:trebuchet ms;">Could we live on the Moon?</span></strong><br /><span style="font-family:trebuchet ms;">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 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">from</span> 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 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_1">brought</span> from Earth could then be grown as food.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">Other moons</span></strong><br /><span style="font-family:trebuchet ms;">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 <span class="blsp-spelling-error" id="SPELLING_ERROR_2">Cassini</span> spacecraft, <span class="blsp-spelling-corrected" id="SPELLING_ERROR_3">launched</span> in 1997, will reach Saturn in 2004 and send a probe to sample Titan's surface.</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-38435301316160528332007-11-23T15:00:00.000+08:002007-11-23T15:14:49.600+08:00<strong><span style="font-family:trebuchet ms;">Moon base</span></strong><br /><span style="font-family:trebuchet ms;">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 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">station would</span> 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.</span><br /><span style="font-family:Trebuchet MS;"></span><br /><span style="font-family:Trebuchet MS;"><strong>Moon's gravity (Astronaut Atletics)</strong></span><br /><span style="font-family:Trebuchet MS;">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.</span><br /><span style="font-family:Trebuchet MS;"></span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-74780514726919785252007-11-22T19:54:00.000+08:002007-11-22T20:06:05.318+08:00MAN ON THE MOON<span style="font-family:trebuchet ms;">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.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">How was the Moon formed?</span></strong><br /><span style="font-family:Trebuchet MS;">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 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">similar</span> 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. </span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-66226307959534970322007-11-22T08:35:00.000+08:002007-11-22T08:43:32.467+08:00<strong><span style="font-family:trebuchet ms;">Is there life on other planets?</span></strong><br /><span style="font-family:trebuchet ms;">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, <span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">light</span> 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.</span><br /><span style="font-family:Trebuchet MS;"></span><br /><span style="font-family:Trebuchet MS;"><strong>Tight squeeze</strong></span><br /><span style="font-family:Trebuchet MS;">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.</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-86169692596694066632007-11-21T15:36:00.000+08:002007-11-21T15:46:50.554+08:00<strong><span style="font-family:trebuchet ms;">Formation of the planets</span></strong><br /><span style="font-family:trebuchet ms;">The planets are all different. Some probably formed mainly from colliding specks of dust, and others from collapsing blobs of gas and dust.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">How was the Earth formed?</span></strong><br /><span style="font-family:trebuchet ms;">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 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">to more</span> than 5000 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_1">Celsius</span> (9000 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_2">Fahrenheit</span>), 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 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_3">Celsius</span> (8100 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_4">Fahrenheit</span>) and the rocks are molten, rising to the surface most spectacularly when a volcano erupts.</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-39811648804592018182007-11-21T09:00:00.000+08:002007-11-21T09:11:46.874+08:00<strong><span style="font-family:trebuchet ms;">The beginnings of Earth making</span></strong><br /><span style="font-family:trebuchet ms;">Particles of dust and rock collided and clumped together to form the beginnings of the Earth</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">4.6 - 4.2 billion years ago :</span></strong><br /><span style="font-family:trebuchet ms;">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.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">4.2 - 3.8 billion years ago :</span></strong><br /><span style="font-family:trebuchet ms;">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.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">3.8 - 2.5 billion years ago :</span></strong><br /><span style="font-family:trebuchet ms;">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.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">2.5 billion - 600 million years ago :</span></strong><br /><span style="font-family:trebuchet ms;">The crust split into mobile plates that began to resemble the continent</span><br /><strong></strong>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-27924668780113705412007-11-20T15:36:00.000+08:002007-11-20T15:46:21.970+08:00THE BIRTH OF THE PLANETS<span style="font-family:trebuchet ms;">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.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">The making of the Earth</span></strong><br /><span style="font-family:trebuchet ms;">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.</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-29336310855736961742007-11-19T15:00:00.000+08:002007-11-19T15:14:01.403+08:00<strong><span style="font-family:trebuchet ms;">Will the Sun last for ever?</span></strong><br /><span style="font-family:trebuchet ms;">Stars last a long time, but not for ever. Our Sun probably reached its peak <span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">brightness</span> 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 <span class="blsp-spelling-corrected" id="SPELLING_ERROR_1">dwarf</span> star before cooling and becoming extinct. </span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">Black holes</span></strong><br /><span style="font-family:trebuchet ms;">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 <em>'black hole'</em> invisible to even the most powerful telescope.</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-26566450313264637922007-11-18T23:33:00.000+08:002007-11-18T23:38:42.938+08:00<strong><span style="font-family:trebuchet ms;">The star dust inside us all</span></strong><br /><span style="font-family:trebuchet ms;">When our Sun was formed 5 billion years ago, temperature reached 15 million c<span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">elsius</span>. 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.</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-64239457182969365652007-11-17T22:54:00.000+08:002007-11-17T23:09:50.187+08:00<strong><span style="font-family:trebuchet ms;">1. Five billion years ago</span></strong><br /><span style="font-family:trebuchet ms;">A spinning cloud of dust and gas collapsed under its own weight. As it did so, the centre began to heat up.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">2. A star is born</span></strong><br /><span style="font-family:trebuchet ms;">As the cloud continued to spin, it flattened into a disc. At the centre of the spinning disc (our future Solar System) lay the embryo, our future Sun, which began to grow as it continued heating up.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">3. Full ignition</span></strong><br /><span style="font-family:trebuchet ms;">When the temperature at the centre of the embryo star reached about 15 million c<span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">elsius</span> (27 million f<span class="blsp-spelling-corrected" id="SPELLING_ERROR_1">ahrenheit</span>), nuclear reactions began turning hydrogen into helium, causing it to radiate heat and light.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">4. Our Sun today</span></strong><br /><span style="font-family:trebuchet ms;">Energy generated in the core of the sun radiates to the surface in great churning currents. At the surface, the temperature is more than 5500 celsius (10 000 fahrenheit), and billions of ton of hot gas flare into space.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">5. Tomorrow's Sun?</span></strong><br /><span style="font-family:trebuchet ms;">When the Sun has burnt up the fuel at its centre, it will start to expand rapidly and cool down, and it will become a red giant.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">6. Star death</span></strong><br /><span style="font-family:trebuchet ms;">The Sun will eventually collapse, squeezing the last particles of fuel so tightly that it will reheat and glow bright white. At this stage, a star is known as a white dwarf.</span>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-7269349643714835197.post-63624271568191412722007-11-17T15:52:00.000+08:002007-11-17T16:03:07.344+08:00<strong><span style="font-family:trebuchet ms;">Making the Sun</span></strong><br /><span style="font-family:trebuchet ms;">The Universe is made up of countless clouds of gas and dust. Around 5 billion years ago. one of this swirling clouds formed a miiling - sized star - our Sun. The energy released by its burning gas provides the light and warmth necessary for life on Earth.</span><br /><span style="font-family:trebuchet ms;"></span><br /><strong><span style="font-family:trebuchet ms;">What makes the Sun shine?</span></strong><br /><span style="font-family:trebuchet ms;">Light from the Sun radiates through the entire Solar System. This light is generated in <span class="blsp-spelling-corrected" id="SPELLING_ERROR_0">the</span> core of the Sun, where temperatures reach around 15 million degree (27 million <span class="blsp-spelling-corrected" id="SPELLING_ERROR_1">Fahrenheit</span>), as hydrogen gas is converted into another gas, called helium, in a series of thermonuclear explosions, billion of times more powerful than the biggest nuclear bombs, are mere pinhead of these gases would be hot enough to ignite everything for 100 km (60 miles) around. The hot gases churn slowly towards the Sun's surface, where the burning solar gas shine for millions of miles into space.</span>Unknownnoreply@blogger.com0