In our part of the world, the days are getting shorter, and the weather's getting cooler, and some of the leaves on the trees are starting to change colors.

在我所處的世界這一端，白天變得越來越短、天氣也越發涼爽，有些樹上的樹葉也開始變色。

This might be happening where you live, too, or it might be happening pretty soon.

這可能也正在你居住的地方發生，或是可能很快就會發生。

That's because we're heading into one of the most colorful times of year: autumn.

那是因為我們即將進入一年內色彩最豐富的時節，也就是秋天。

Nothing says autumn or fall like lots of brightly-colored leaves to rake and jump into or just to pick up and admire.

沒有比把多彩落葉耙成一堆然後跳進去或是撿起一片鮮豔落葉欣賞更能代表秋季的事情了。

Now, some trees like pine trees, spruces, and firs stay green all autumn and winter.

有些像是松樹、雲杉和樅樹等樹木在秋、冬季也是常綠。

But for many of the trees that have leaves instead of pointy needles, this time of year means their leaves will turn different shades of red, orange, and yellow, and eventually drop to the ground.

但對於許多有闊葉而不是尖尖針葉的數目來說，這個季節意味著它們的樹葉會轉變為不同色階的紅、橘、黃色，最終掉落地面。

Have you ever wondered why this happens?

你有想過這為什麼會發生嗎？

To find out, let's take a close look at a green leaf.

要找出答案，我們先仔細看看一片綠葉。

Leaves on most plants and trees are green because of a colorful chemical inside them called chlorophyll.

多數植物和樹木上的葉片之所以是綠色的是因為它們內部稱為葉綠素的多彩化學元素。

Chlorophyll is bright green, but it does more than just look pretty.

葉綠素是亮綠色的，但它可不只是好看而已。

It has a special job because it's able to capture the energy that's in sunlight.

它有一個特別的任務，因為他能夠捕捉在陽光中的能量。

Leaves use this light energy to make sugars, which the tree can then use for its own energy.

樹葉會利用這個光能製造糖分，樹木則可以用它來提供自身能量。

So, chlorophyll is what plants use to make their own food from sunlight.

所以說，葉綠素是植物用以從陽光製造糧食的東西。

But chlorophyll isn't the only thing in tree leaves that gives them color.

但是給予樹葉色彩的並不只有葉綠素。

Leaves have lots of other colorful chemicals called pigments inside them that are red, yellow, orange, and even purple.

樹葉中有許多稱為「色素」的多彩化學物質，包括紅、黃、橘，甚至紫色。

If you've eaten carrots, cabbage, or cherries, then you've not only seen these pigments; you've had them for lunch.

如果你吃過紅蘿蔔、紫高麗菜或是櫻桃，那麼你不只是看過這些色素，你午餐還吃過它們。

All of these colorful pigments have special jobs, but only chlorophyll helps a plant make the sugar that it needs to live.

這些多彩的色素都有特殊的任務，但是只有葉綠素能夠幫助一株植物製造賴以生存的糖分。

And since chlorophyll's job is so important, there's way more of it in green leaves than any of the other pigments.

而由於葉綠素的工作如此重要，它在樹葉當中的含量比其它色素都要多得多。

In fact, there's so much chlorophyll that its green color covers up all of the other colors.

事實上，葉綠素多到綠色素會完全覆蓋其它所有色彩。

So, through spring and summer, we don't see the red, yellow, and orange pigments in the leaves; we just see the green chlorophyll.

所以在春、夏期間，我們不會看到葉子裡的紅、黃、橘色素，只會看到當中綠色的葉綠素。

But as summer starts to turn into fall and the days get shorter, less and less sunlight hits the tree's leaves.

但隨著夏季開始邁入秋季、白天也開始變短，會有越來越少的陽光照耀到樹葉上。

So, the tree starts to make less and less chlorophyll.

所以樹木製造的葉綠素也會開始越來越少。

Then, the leaves become less green, and we're able to see more of the other colors that were there all along.

接著，樹葉會變得比較不綠，我們就能夠看到更多那些一直都存在的其它顏色。

And when that starts to happen, you might want to take the time to enjoy these pretty leaves while you can, because not long after they turn color, they begin to fall.

而當那開始發生時，或許你可能會在還許可的狀況下撥時間好好欣賞這些美麗的樹在，因為它們會在變色之後不久開始掉落。

They fall because, without their chlorophyll to help them make energy, the leaves don't really have a job to do.

它們掉落的原因是，少了幫它們製造能量的葉綠素，樹葉其實就沒有工作可做了。

So, as winter approaches, the energy that the leaves have made flows into the tree and gets stashed away.

所以隨著冬天逼近，樹葉製造出的能量會轉移到樹木上並儲存。

Then, when the time is just right, they break off from the branches and fall to the ground.

然後到了對的時機點，它們就會脫離樹枝然後墜落地面。

The tree can then live through the winter using the energy that it's saved up until the days start to get longer and warmer.

樹木可以藉由儲存的能量度過寒冬，直到白天重新開始變得更長、更暖活。

Then it grows new leaves to capture the sunlight, and the cycle starts all over again.

然後它會長出新葉捕捉陽光，然後這個循環就會再次從頭開始。

So, when you start to see yellow, orange, and red leaves showing up where you live, remember:

所以當你開始在生活環境中開始看到黃色、橘色和綠色樹葉時，要記住：

Those colors were there are all along⏤autumn is just their time to shine.

那些色彩一直都是存在的，只是秋天才是它們發光發熱的季節。

Thanks for joining me on SciShow Kids; what's your favorite colored leaf?

謝謝大家收看今天 SciShow Kids 的節目，你最喜歡什麼顏色的樹葉呢？

If you've found an extra pretty one, get an adult to help you take a picture of it and send us an email at kids@thescishow.com, and we'll see you next time.

如果你找到格外美麗的一片樹葉，那就找個大人幫你拍下它的照片，然後傳送到 [email protected] 給我們，我們下次見。