(单词翻译:单击)
Hi guys! What's it like outside this time of year where you live?
大家好！这时节你居住地外面是怎样的情景？
In our part of the world, the days are getting shorter, and the weather's getting cooler,
我们这地区，白天越来越短，气温越来越低
and some of the leaves on the trees are starting to change colors.
树上的叶子正开始变色
This might be happening where you live too—or it might be happening pretty soon.
这种现象可能在你的居住地也正上演着，或是即将上演
That's because we're heading into one of the most colorful times of year—autumn!
那是因为我们正在进入一年中最五彩缤纷的季节——秋季
Nothing says autumn or fall like lots of brightly colored leaves to rake and jump into, or just to pick up and admire.
没有什么比色彩鲜艳的积叶更能代表秋天，我们可以跳进树叶堆中，或者拾起它们慢慢欣赏。
Now, some trees—like pine trees, spruces and firs—stay green all autumn and winter.
松树，云杉和冷杉等树木在秋冬季节仍旧保持绿色
But for many of the trees that have leaves, instead of pointy needles,
但在这个季节，除了针木植物，
this time of year means their leaves will turn different shades of red, orange, and yellow and eventually drop to the ground.
其他有叶植物的树叶都会从红色变成橘色再变成黄色，最后落到地面
Have you ever wondered why this happens?
你知道这是怎么发生的吗？
To find out, let's take a close look at a green leaf.
让我们仔细观察绿叶来寻找答案吧
Leaves on most plants and trees are green because of a colorful chemical inside them called chlorophyll.
大多数植物的叶子成绿色是因为它们体内有一种叫叶绿素的化学物质
Chlorophyll is bright green. But it does more than just look pretty!
叶绿素是翠绿色的 但它不仅仅是看着好看
It has a special job, because it's able to capture the energy that's in sunlight.
它还有一种特殊的功能，能在阳光下吸收太阳能
Leaves use this light energy to make sugars, which the tree can then use for its own energy!
树叶利用太阳能制造糖类物质，供给树木用作自身能量
So chlorophyll is what plants use to make their own food from sunlight!
所以，叶绿素是植物利用太阳光吸收能量、给自己制造食物的工具
But, Chlorophyll isn't the only thing in tree leaves that gives them color.
但叶绿素不是唯一一种让树叶变绿的物质，
Leaves have lots of other colorful chemicals—called pigments—inside them, that are red, yellow, orange, and even purple.
树叶中还有其他的名为色素的化学物质，颜色包括红色、黄色、橘色甚至是紫色
If you've eaten carrots, cabbage, or cherries,
如果你吃过胡萝卜、大白菜或是樱桃，
then you've not only seen these pigments, you've had them for lunch!
那么你不光看到过这些色素，你还把它们当晚餐吃过
All of these colorful pigments have special jobs,
所有这些色素都有特定的功能 ，
but only chlorophyll helps a plant make the sugar that it needs to live.
但只有叶绿素能帮植物产生它生存所需要的糖类物质
And since chlorophyll's job is so important,
因为叶绿素的功能如此重要
there's way more of it in green leaves than any of the other pigments.
所以绿叶中叶绿素的含量要比其他色素的含量多得多
In fact, there's so much chlorophyll that its green color covers up all of the other colors.
事实上 过多的叶绿素把其他的色素都盖住了
Through spring and summer, we don't see the red, yellow, and orange pigments in the leaves—we just see the green chlorophyll.
在春夏季节， 我们看不到树叶里的红、黄和橘色素，只能看到绿色素
But as summer starts to turn into fall, and the days get shorter, less and less sunlight hits the tree's leaves ...
但从夏季进入秋季后，白天变短，照到树叶的阳光越来越少
so the tree starts to make less and less chlorophyll.
所以植物产生的叶绿素也越来越少
Then the leaves become less green, and we're able to see more of the other colors that were there all along!
因此，树叶的绿色减少， 我们就能看到一直存在的其他颜色了
And when that starts to happen, you might want to take the time to enjoy these pretty leaves while you can...
当发生这种变化时 你可能想在有限的时间内花些时间欣赏这些漂亮的树叶
because not long after they turn color, they begin to fall!
因为它们变色不久后就会掉落
They fall because, without their chlorophyll to help them make energy, the leaves don't really have a job to do.
掉落的原因是没有叶绿素制造能量，树叶就没什么作用了
So as winter approaches, the energy that the leaves have made flows into the tree, and gets stashed away.
所以冬季来临时，树叶中的能量进入了树中且被储藏起来
Then, when the time is just right, they break off from the branches and fall to the ground.
时间一到，树叶就从树干掉落到地面
The tree can then live through the winter, using the energy that it's saved up,
然后树就可以依靠储存的能量度过冬天了，
until the days start to get longer and warmer.
直到天气变暖，白天变长
Then it grows new leaves to capture the sunlight...and the cycle starts all over again.
然后树木开始长出新叶吸收太阳能 循环又开始了
So when you start to see yellow, orange and red leaves showing up where you live,
所以当你看到周围的树叶开始变成黄色、橘色和红色时，你就会知道什么季节了
remember those colors were there are all along—Autumn is just their time to shine!
记住，这些颜色一直都在，秋天只是它们登场的季节
Thanks for joining me on SciShow Kids. What's your favorite colored leaf?
感谢收看SciShow Kids，你最喜欢哪种颜色的树叶呢？
If you found an extra pretty one, get an adult to help you take a picture of it
如果你发现一片十分漂亮的树叶，让大人帮你拍个照
and send us an email at kids@scishow.com! And we'll see you next time.
然后发邮件到邮箱kids@scishow.com。我们下期见
