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EXTRATERRESTRIAL LIFE

Extraterrestrial life means life beyond Earth, or alien life. No life has been found on other planets in the Solar System, but it might exist on planets around other stars.

HOW CAN LIFE EXIST ON OTHER PLANETS?

Life could be widespread on distant planets because the necessary elements, such as carbon, hydrogen, and oxygen, are common in space. A living planet also needs warmth, light, and an atmosphere. In SETI projects, astronomers are searching for intelligent life.

SIGNS OF INTELLIGENCE

The radio signals caused by stars, planets, and other bodies look like fuzzy noise on a computer screen. If astronomers spot a pattern in the signals, it could be proof of extraterrestrial life.

SETI

SETI stands for the Search for Extraterrestrial Intelligence. Astronomers tune in to radio waves from outer space, looking for coded signals that might come from other intelligent beings.

ARE WE SENDING ANY MESSAGES INTO SPACE?

In 1974, the Arecibo radio telescope beamed a radio message to the stars in digital code, describing life on Earth. Pictures and sound recordings have also been carried into space by the probes Pioneer 10 and 11, and Voyager 1 and 2.

Copyright © 2007 Dorling Kindersley

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