So now we know why plants appear to be green. They reflect green light and absorb the other colors of light. When we try to grow plants in space, this information can be useful for scientists. Spacecraft are not hooked up to power stations and they cannot pull up to a gas station either. Spacecraft like the space shuttle have a limited amount of energy. If we need to run lights to grow plants on these spacecraft, that takes energy. But we may be able to reduce that amount of energy by only providing the plants one or two colors of light instead of all colors.

Did you know that plants can also move? They usually do so by growing in a certain direction, towards light, water, gravity or even away from other plants. These movements and responses are called tropisms. Phototropism is when plants grow towards the light. Remember in Mission 2 when we learned about plants responding to gravity, or gravitropism?

Click here to view a video showing phototropism.
(The video is courtesy of Roger Hangarter's lab)

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