The search for life

The planet Earth. Photo: Nasa.

For as long as people have inhabited Earth, they have been asking that very question. The prospect of humans not being the only race alive in the vast universe has been taxing the minds of the greatest scientists and thinkers for centuries, it seems. The popularity of shows such as Star Trek, the X Files and various Alien movies, enthral many and perpetuate the prospect of life on other planets.

Recently, a huddle of seven worlds, all close in size to Earth, and some perhaps warm enough for water and the life it can sustain, were spotted around a small, faint star in the constellation of Aquarius. All seven could  support liquid water on the surface, depending on their other properties. But only three are within the ‘‘Goldilocks’’ zone —  neither  too hot nor too cold — where life is considered a possibility.

The new planets are  close to each other and a person standing on the surface of one would have a view of its neighbours, similar to seeing the moon from Earth.

Lead author of the study released in the journal Nature, Michael Gillon, says it will be disappointing if Earth represents the only template for habitation in the universe.

The discovery has raised hopes the hunt for alien life beyond the solar system may start sooner than previously thought and probably within the next generation by telescopes due to turn on within 10 years.

The planets closely circle a dwarf star named Trappist-1, which, at 39 light years away, makes the system a prime candidate to search for signs of life. Only marginally larger than Jupiter, the star shines with a feeble light about 2000 times fainter than the sun. The star is said to be so small and cold that the seven planets are temperate, meaning they could have some liquid water and maybe life on the surface. The excitement following these latest discoveries is not only because of the unusual scale or the fact so many of the planets are Earth-sized. It is also because the Trappist-1 star is helpfully small and dim. That means telescopes studying the planets are not dazzled as they would be when aiming at far brighter stars. Experts say that opens up a fascinating avenue of research into these distant worlds, and, above all, their atmosphere. The next phase of research has already started with a search for key gases such as oxygen and methane, which may provide evidence about what is happening on the surface.The Hubble telescope could detect methane and water in the alien air but both can be produced without life. More complex and convincing molecular signatures might be spotted by Nasa’s James Webb Space Telescope, which is due to launch next year.The whole debate of whether Earth is the only inhabited planet in the universe will continue, in the meantime. Religious thought on how Earth was created will come up against scientists who will argue vehemently for their point of view to be taken seriously.

But there needs to be deeper thought and consideration on whether we are actually alone. If there is another inhabited planet, how will Earth look to them and can they already see us? Is life for them still emerging out of the swamps or is life sophisticated. Does Earth represent the very best of humanity? And the answer will probably be no, given the wars, famine and political situations now affecting the planet.Life may have evolved on at least three of the newly discovered planets, giving the chance of finding a second Earth not a matter of if but more of when. There is only so much that can be done from Earth, making the next few years even more exciting. And no-one can be sure until someone actually goes to the planet.

In the meantime, we  have just our imaginations to fill in the gaps.