– LIFE IN SPACE –
-> Hopes of finding life on other worlds have been raised by Canadian
astronomers. Their observations of nearby stars have shown that half of
them may have planets.
The discovery, announced at a recent meeting of the American Astronomical Society, provides important support for scientists who believe that planetary systems, and life, are common in our galaxy.
“These observations suggest that half our galaxy’s 100,000 million stars have planets – and that means we must have a good chance of finding life ‘out there’,” said Professor Archibald Roy of Glasgow University.
The research, carried out by Dr. Bruce Campbell of the Dominion Astronomical Observatory, Victoria, and Dr. Gordon Walker and Dr. Stephenson Yang of the University of British Columbia, Vancouver, employed a new astronomical measuring technique called high-resolution spectroscopy.
In the past, the search for other worlds has been limited by two factors. First, planets are tiny, i.e. very small, objects compared with stars; for instance, the sun, a typical star, is 300,000 times more massive or larger than the earth.
Second, planets do not shine but only reflect (give back) light from stars.
But Dr. Campbell and his colleagues solved this problem by using high-resolution spectroscopy to measure variations in a star’s light.
Small differences in a star’s light showed that unseen planets pushed and pulled the stars out of their paths, in other words, their ways.
The astronomers’ results, published in the Science magazine showed that, of 16 nearby stars, two – Epsilon Eridani and Gamma Cephei – were definitely being affected by large bodies in orbit round them. Of the rest, five or six also appeared to have unseen companions.
The astronomers calculate that these unseen objects must be several hundred times more massive than Earth. However, they are almost certainly planets.
“There are about 100,000 million stars in our galaxy and about one fifth are stable: that is, unchanging and cool like our own sun.” said Professor Roy. “Now it seems about half also have planets. That leaves us with 10,000 million stars which might have life on them. It’s very encouraging.”
Further evidence should follow, because in a few years two important space projects – the Space Telescope and a European satellite called Hipparchus – will be introduced. Both will increase scientists’ powers to find out minute variations in stars’ motions caused by orbiting planets.
In addition, a programme called the Search for Extraterrestrial Intelligence (SETI) will concentrate on studying radio waves from stars which may have life-supporting planets.
Today, many scientists believe that by the end of the century we may have an accurate answer to the fundamental question: are we alone?