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Learn about planets outside our solar system through Exoplanets and Alien Solar Systems by Tahir Yaqoob, Ph.D., a book in our online store book collection.

Exploratour - Life in the Solar System

Life on Earth obtains energy in many types of formats. The two main process are photosynthesis and respiration. Photosynthesis is the name of the process by which autotrophs (self-feeders) convert water, carbon dioxide, and solar energy into sugars and oxygen. Oxygen is a waste product of this activity. The photosynthetic activity of early bacteria helped build the oxygen content of Earth's atmosphere so that oxygen-dependent animals, including humans, could live.

The reverse of this process, used by heterotrophs (other-feeders) coverts sugars and oxygen into biological energy. Carbon dioxide and water are produced as waste products.

Respiration, unlike photosynthesis, takes advantage of a natural tendency of oxygen to combine with other molecules. When combining with other substances, oxygen tends to release large amounts of energy. Thus life forms which employ the process of respiration are taking advantage of the most efficient and energetic pathway nature provides to produce bioenergy on Earth.

Certain forms of bacteria can covert energy by breaking down exotic molecules without the benefit of photosnythesis or respiration, however. An example is the coversion of acetate to methane by Archaea. Likewise, life elsewhere in the solar system may rely on an energy conversion process which has yet to be discovered by human science. One way to search for life is to try and detect the waste products from life's activity. Read more about NASA's current attempts to search for life in the Exploratour on NASA's Exploration for Life at the bottom of this page.

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Traveling Nitrogen Classroom Activity Kit

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ExploraTour - Looking at the World in a Different Light

Even though the sleeping man is no longer on the bed, you can still see where he was lying down. The heat from his body warmed up the bed sheets which are now radiating infrared light toward your eyes....more

ExploraTour - Looking at the World in a Different Light

All warm objects (not just people) radiate in the infrared. Warmer objects give off more infrared radiation. Very hot objects radiate other types of light in addition to infrared. Click on the picture...more

ExploraTour - Looking at the World in a Different Light

Your eye is a wonderful detector of visible light. Different frequencies of light produce different sensations in the eye which we interpret as colors. Our eyes detect light by using light sensitive components...more

ExploraTour - Looking at the World in a Different Light

Imagine you found a pair of special glasses that not only gave you telescopic vision but gave you the ability to see all forms of radiant energy. The universe in visible light contains all the familiar...more

ExploraTour - Looking at the World in a Different Light

This is a volcano on the island of Miyake in Japan. It has erupted, sending hot lava and ash into the air, a total of ten times. The time after one eruption until the next occurred was about twenty years...more

ExploraTour - Looking at the World in a Different Light

This is a picture of a galaxy in visible light. A galaxy is a large number of stars, some like our sun, some bigger, some smaller and all moving together through space. This galaxy is called Centaurus...more

ExploraTour - Looking at the World in a Different Light

This is a plant in Gary, Indiana where power is made. We use power to run things like television sets, radios, lights, and microwave ovens. The picture looks very strange because it was taken in infrared....more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF