Out of Thin Air

Have you ever looked up at a tall, leafy tree and wondered, “How did it get so big?” For a long time scientists did not know. They thought plants, like animals, had to “eat” to grow. The scientists guessed that plants “ate” something in soil.

Today we know that plants build themselves mostly from the air. That is where they get carbon, a building block for life. The carbon plants use comes from carbon dioxide, a gas in the air. Plants turn carbon dioxide and water into food. This is called photosynthesis, and it takes place inside green leaves. Why green leaves, you might ask? What about when leaves change their color?

You likely see big, green, leafy trees, like this one, all the time. Did you ever stop to wonder why leaves look green, though?View Larger Image

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