<h3 style="text-align: center"><b>地球日主題1：Earth and Human</b></h3><div>切入地球日主題，先來了解下我們所生存的星球-地球，它的結(jié)構(gòu)，它為我們提供哪些資源，水，空氣，食物、能源等，這些資源并非取之不盡，為保護(hù)地球做鋪墊。</div><div><br></div><div><b>Earth</b> is the third planet from the sun in our solar system. Its name comes from the the old English and Germanic words meaning 'the ground'.地球是太陽系中來自太陽的第三個(gè)行星。 它的名字來自古老的英語和日耳曼語單詞，意思是“地面”。</div> Our amazing planet has been around for quite some time. By researching our planet's rocks, scientists have calculated the Earth to be around 4.5 billion years old! 我們神奇的星球已經(jīng)存在了很長一段時(shí)間。 通過研究我們星球上的巖石，科學(xué)家們計(jì)算出地球大約有45億年的歷史！ People often think of Earth as a gigantic sphere. But, in fact, its shape is more like a squished ball that bulges out at the equator –– an imaginary line around the middle of the planet, exactly between the North Pole and the South Pole.人們經(jīng)常將地球視為一個(gè)巨大的領(lǐng)域。 但是，實(shí)際上，它的形狀更像是一個(gè)在赤道上凸出的壓扁的球，這是一條圍繞行星中部的假想線，正好位于北極和南極之間。<div>This 'bulge' is caused by the Earth's spin and the effect of 'gravity'. Gravity is an invisible force that attracts objects towards each other. It's this force that pulls things towards the Earth and stops us floating off into space! 這種“凸起”是由地球的自轉(zhuǎn)和“重力”的作用引起的。 重力是一種無形的力量，可以將物體吸引到彼此之間。 正是這種力量將事物拉向地球，阻止我們漂浮到太空中！<br></div> Earth is the only planet in our solar system known to support life. This is because it has two very important things that living creatures need to survive –– lots of oxygen and lots of water! Its distance from the sun means it's not too hot and not too cold for creatures to live on, too.地球是已知太陽系中唯一能夠維持生命的行星。 這是因?yàn)樯锉仨毶嬗袃蓚€(gè)非常重要的條件–大量的氧氣和大量的水！ 它與太陽的距離不大，也不至于讓生物賴以生存。<div>Earth's 'atmosphere' is also hugely important for sustaining life. The atmosphere is a huge blanket of gases – mostly oxygen and nitrogen – wrapped around Earth, protecting our planet from the sun's strong rays. At the same time, the atmosphere helps keep the Earth's temperature comfortable for living beings – and it protects us from meteors, too!地球的“大氣層”對(duì)于維持生命也非常重要。 大氣層包裹著大片氣體（主要是氧氣和氮?dú)猓?，保護(hù)了我們的星球免受太陽的強(qiáng)光照射。 同時(shí)，大氣層有助于保持地球?qū)θ祟惖氖孢m溫度-并保護(hù)我們免受流星的侵害！<br></div><div><br></div><div><b>1. Layers of earth</b></div><div>There are 4 layers to the Earth: the crust, the mantle, the outer core, and the inner core. Here are some of the cool facts we learned.<b><br></b></div> <b>? Crust </b>is a outer most layer of earth. This the layer in which we are living. It is said that thickness of crust is from 8km to 32km. It consist of all oceans, cultivable land, mountains,etc. Even the bottom of the deepest ocean is still part of the crust. That means every single bit of life on the Earth is found on the crust. There is no type of life form that inhabits any other layer of the Earth.<br>? The crust is the only layer we can actually reach. It is the only layer scientists are able to drill into and it is definitely the layer we know the most about.<br><b>? Mantle</b> is the second outer layer of earth. 85% of the Earth's weight comes from the mantle! It is by far the biggest layer. It's made of solid rock, but since it is so hot the rock isn't completely hard. It's more like the texture of molding clay and it slowly moves. That movement causes earthquakes and volcanic eruptions!<br><b>? The outer core</b> <b>is liquid rock</b> and it is HOT! We don't know the exact temperature, but some estimates put it at 4,000 -6,000 degrees Celsius.<br><b>? The inner core is solid rock.</b> Even with the mega hot temperatures the rock can't melt because of the amount of pressure down that the inner core is under. In fact it is as hot as the sun! <b>Handcraft:</b><br>To make the beads we picked 5 colors of clay. We used pink for the inner core, orange for the outer core, yellow for the mantle, and of course blue and green for the crust.<br><br>We started by rolling little balls of pink clay. Then we flattened little pieces of orange clay, stuck them all over the outside, and then re-rolled our balls. We repeated the process with the yellow clay and the blue clay. At the end we added some pieces of green on the top and re-rolled our balls one last time.<br> <b>2. Top 5 Natural Resources on the earth</b><div><b>(1) Water</b></div><div>One of the most important natural resource is water. Our Earth is a water planet and ? of the planet is covered with this life-giving resource. You'd think we'd have enough supply. But 97% of all the water on the planet is salty, we cannot drink it. Only 3% is freshwater, and 2% of that is frozen in the ice caps or in glaciers. In reality, we only have 1% of freshwater available.<b><br></b></div> <div><ul><li>Fresh water is a renewable resource, but somehow, the world's supply of groundwater is being depleted at an alarming rate. We use water for so many of our activities – in the household, in agriculture to grow crops and animals, during recreation, in the factories – most of our activities require freshwater. Only a very small percentage of our water supply is used for drinking.<br></li><li>Freshwater can be found either in the surface or underground. On the surface, it’s found on rivers and lakes. It’s replenished when it rains and it is depleted through evaporation.<br></li><li>Groundwater is located beneath the earth, between soil and rocks. This is where we get our water supply at home.<br></li><li>Frozen freshwater, is found in glaciers, icebergs and in the polar icecaps. The problem is due to global warming, these valuable sources are melting. If they all melt, that would severely deplete our sources of freshwater.</li></ul><p><b>(2) Sunlight</b></p></div> Another valuable resource that we take for granted. Although you can't measure how much of it we use, and you don't notice the effect we have on it. We may not be able to affect the sun, but if we continue to pollute the environment, someday, the nourishing rays of the sun may not reach us anymore.<div><b><br></b></div><div><b>(3) Air</b></div> Without the oxygen we breathe, we will perish. It's that simple. Contaminated air causes all kinds of health problems. Look at the smog covering our cities… that's what we're breathing today. That's why asthma and other pulmonary problems are common these days. We can help minimize pollution by riding bikes on short distances, and not using our vehicles too much. We can also patronize companies who manufacture their products without polluting the environment.<div><br><div><b>(4) Rainforests</b></div></div> <ul><li>Trees provide oxygen to the planet and these magnificent resource gives us shade. It keeps cities from flooding and absorb the carbon dioxide in the air. Unfortunately, it was also used to make paper and is a highly coveted resource. Not just the trees, but the land itself. As our cities grew, we chopped down acres of forest to clear the land.<br></li><li>It is said that by 2030, we may only have 10% of our rainforests left. Just imagine what happens to all the living things in the forest. Whole ecosystems die when we clear an area. To date, over 13 million hectares of forests have been converted for other uses. Can you imagine our world without trees?<br></li><li>To help save trees, reuse and recycle paper, or don't use them at all. Many companies and individuals are going paperless to save our rainforests.<br></li></ul><p><b>(5) Coal</b></p><p>Coal is the cheapest energy resource and the most abundant in the fossil family. Humans have utilized it from the time of our cavemen ancestors. What keeps it from being the best thing ever discovered, is its negative effect to the environment.<b><br></b></p> <br>? The use of Coal is the cause of 40% of the carbon dioxide emissions from fossil fuels<br>? It is a primary contributor to global warming<br>? Coal mining is a hazardous job, and has caused thousands of deaths among the workers since it was discovered.<br>