It is long known that Earth's orbit around the Sun changes periodically, cyclically affecting the way solar radiation strikes the Earth.
人们早就知道，地球围绕太阳的轨道会周期性地变化，周期性地影响太阳辐射照射地球的方式。
These early ancestors of modern Eurasians disperse into parts of the world that had more seasonal sunshine and much lower levels of sun radiation.
这些现代欧亚混血儿的早期祖先分散到世界各地，那里有更多的季节性日照和更低水平的太阳辐射。
For instance, without a tree to absorb radiation from the Sun, to offer shade, the full intensity of that radiation reaches the ground.
例如，如果没有树木来吸收太阳的辐射并提供树荫，那么太阳辐射就会完整地到达地面。
Many types of radiation, especially ultraviolet rays from the Sun, can damage skin cells and cause cancer.
许多类型的辐射都会损害皮肤细胞并导致癌症，尤其是来自太阳紫外线的辐射。
Cosmic rays of various kinds come through the air from outer space, but enormous quantities of radiation from the sun are screened off.
来自外太空的各种宇宙射线通过空气进入大气层，但来自太阳的大量辐射却被屏蔽了。
They were started by slow and subtle shifts in the orbit of the Earth that changed the amount and distribution of radiation reaching us from the sun.
地球轨道缓慢而微弱的变化改变了阳光照射我们的数量和辐射的分布，从而引发了这些变化。
Each of us is exposed to radiation daily from natural sources, including the Sun and the Earth.
我们每个人每天都暴露在不同的辐射中，包括来自太阳、地球的天然辐射。
Radiation from the sun pushes dust particles away from the coma, forming a dust tail, while charged particles from the sun convert some of the comet's gases into ions, forming an ion tail.
从太阳而来的辐射，将尘埃粒子吹离彗发，形成尘埃彗尾；同时，来自太阳的带电粒子将一些彗星气体电离成离子，形成离子彗尾。
A study has shown that compounds found in the fruit protect cells from the ultraviolet radiation emitted by the sun - the leading environmental cause of skin cancer.
一项研究表明，在葡萄中发现的化合物能保护皮肤细胞，防止太阳紫外线的辐射，而紫外线正是诱发皮肤癌的首要环境因素。
Sun elevation: the higher the sun in the sky, the higher the UV radiation level.
太阳高度：太阳在空中越高，紫外线辐射水平就越高。
We predict that whales will experience more severe sun damage if ultraviolet radiation continues to increase.
如果紫外线辐射继续加强的话，我们预计鲸鱼将遭受更严重的晒伤。
Flares are intense explosions on the Sun that blast radiation into space.
太阳耀斑是一种剧烈的太阳爆发活动，可向空间中释放大量辐射。
As one side of a rotating body (i.e. an asteroid) is heated by the sun's radiation, the surface rotating away from the sun will be warmer than the surface rotating into sunlight.
对于旋转的天体(例如小行星)而言，其一侧由于受太阳的辐射而会被加热，这样，即将离开阳光的那一侧的表面由于经过了阳光的照射而比将要进入阳光照射的一侧温度会高。
I am told that I should want to see the sun someday-when the dust settles, and the radiation is gone.
我被告知应该在某一天想去看看太阳，当尘埃落定，当放射物消散。
Nasa has warned that a peak in the sun's magnetic energy cycle and the number of sun spots or flares around 2013 could generate huge radiation levels.
NASA（北美航天局）警告称，太阳磁能循环可能在2013年左右达到顶峰，大量的黑子和耀斑出现，将会导致辐射强度急剧增大。
Know the UV index: when the UV index predicts radiation levels of 3 (moderate) or above sun safety practices should be taken.
了解紫外线指数：当紫外线指数预报辐射级别为3(中度)或更高时。
Ozone: ozone absorbs some of the UV radiation from the sun.
臭氧：臭氧吸收一些太阳紫外线辐射。
However, the sun also gives off a whole lot of infrared radiation. What would it be like if our eyes evolved to see infrared light?
然而，太阳的不可见光辐射也不在少数，要是我们眼睛能够进化成可见其他光线会是什么景象？
Like the ozone layer, the magnetosphere is important to life on Earth because it protects us from most of the harmful radiation and hot plasma from the Sun, deflecting it into space.
与臭氧层类似，磁层对地球生物至关重要，绝大多数来自太阳的有害射线和热等离子体都被地球磁层折射回太空，从而使我们免受伤害。
Whales are continuously exposed to the sun and are now suffering skin damage as ultraviolet radiation increases.
——鲸鱼持续不断地暴露在太阳下，而如今却因紫外线辐射的增加而使皮肤遭受损害。
These are prime hours for exposure to skin-damaging ultraviolet (UV) radiation from the sun, even on overcast days.
这段时间是皮肤受到太阳紫外线照射伤害的主要时段，即使是阴天也是如此。
Ultraviolet radiation from the sun causes a considerable global disease burden, including specific cancers, a new World Health Organization (WHO) report finds.
一份新的世界卫生组织(世卫组织)报告查明，太阳紫外线辐射造成相当大的全球疾病负担，包括特定癌症。
The sun, in addition to emitting radiation, emits a stream of ionized particles called the solar wind that affects the Earth and other planets in the solar system.
除了辐射外，太阳还会释放出一种被称之为太阳风的带电粒子流，这种粒子流会对地球以及太阳系中的一些其它星球产生一定的影响。
The Earth’s surface emits infrared radiation it has absorbed from the sun. Greenhouse gases partly trap that energy as heat, keeping the planet habitable.
地球表面释放出从吸收自太阳的红外辐射，温室气体将这种能量作为热部分地保留下来，使得地球成为可以繁衍生息之地。
It is because one type of radiation emitted by the sun, ultraviolet (UVR), is believed to cause genetic changes in the developing baby that may have a shaping effect, either beneficial or harmful.
因为，太阳所发出的一种光线叫作紫外线（UVR），它可以造成胚胎期的婴儿的基因变化，从而造成可感知的后果，这种后果有好有坏。
This is where the planet's ozone layer sits, filtering out ultraviolet radiation from the sun.
地球臭氧层位于平流层，过滤来自太阳的紫外线辐射。
The outer layers of space suit protect against harmful radiation from the Sun and bullet-fast particles of space dust called micrometeoroids.
宇航服的外层能够防御太阳辐射和高速微流星体造成的伤害。微流星体是指太空中的微小尘粒。
Mars has no magnetic field, so the surface is constantly bombarded by radiation from the sun.
火星没有地磁场，因此地表经常遭受太阳辐射的袭击。
Trimming lead times on sunspot detection would allow for better forecasts of space weather—bursts of radiation and charged particles from the sun that can cause real problems on and around Earth.
黑子探测可用于预报空间天气---即源于太阳的辐射爆发和带电粒子等引起的各种空间活动现象。
This last cooling effect is caused by a decline in ozone in the stratosphere which prevents it absorbing as much ultraviolet radiation from the sun above.
最后一项变冷效应是由于平流层臭氧减少所致，而臭氧可抑制平流层从太阳吸收紫外线。
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