Posts Tagged ‘SETI’

Two ‘Super Earths’ Discovered around Nearby Star, Tau Ceti

August 10, 2017

Today’s I newspaper, for Thursday 10th August, has the news that two planets, which may be suitable for human colonization, have been found around Tau Ceti, a nearby star similar to our Sun.

The paper says on page 2

Astronomers have discovered two potentially habitable “super-Earths” orbiting a star 12 light years away. British led experts have identified four rocky planets, similar in size to Earth, in Tau Ceti’s “habitable zone” orbiting the nearest Sun-like solar system, neighbouring ours.

John Von Radowitz’s article, The Climate’s Nice 12 Light Years Away on page 5 also adds that the two ‘super-Earths’ are at the edge of Tau Ceti’s “habitable zone”, and that

British-led astronomers speculate that the system might be a potential candidate for future interstellar colonization. But there is evidence of a massive debris disc circling the star, increasing the chances of the planets being pounded by asteroids and comets.

Dr. Fabo Feng, the lead researcher from the university of Hertfordshire, said: “We’re getting tantalizingly close to observing the correct limits required for detecting Earth-like planets.

“Our detection…is a milestone in the search for Earth analogues and the understanding of the Earth’s habitability.”

The findings are to be published in ‘The Astronomical Journal’.

Philip’s Astronomy Encyclopedia (London: Philips’, 2002) states that Tau Ceti ‘is the most Sun-like of all the nearby single stars’. (‘Cetus’, p. 81), and that it is a G8-type star lying at a distance of 11.9 light years. This means its a yellow dwarf star like our Sun.

Tau Ceti is one of the stars making up the constellation Cetus, and is quite visible, unlike some of the other nearby stars, like Barnard’s Star. It’s so much like Sun that it was one of two stars, the other being Epsilon Eridani, which were the subject of Project Ozma in 1960. This was a program led by Frank Drake, using the 26 metre radio telescope at Green Bank to listen for possible signs of alien civilisations broadcasting messages along the 21 cm band. That wavelength was selected because it’s close to the wavelength occupied by the noise of cold hydrogen in space. Drake and his fellow scientists believed that it would therefore be a natural wavelength for advanced alien civilisations to use to broadcast to each other across the vast gulfs of space.

The search was, however, unsuccessful, and after a couple of months it was discontinued. Frank Drake still remains an influential figure in the Search for Extra-Terrestrial Intelligence (SETI) for his formulation of the Drake Equation, a formula which allows the number of possible alien civilisations in our Galaxy to be calculated.

The Equation has also come under attack. James E. Oberg, a NASA scientist, criticized it over thirty years ago in his article, ‘New Case Against Extraterrestrial Civilisations’ in the 1981 Yearbook of Astronomy. Part of the problem with the equation is that no-one actually knows how common Earthlike planets are, nor how likely the emergence of life is, and how like intelligent, technological life is either. According to the numbers selected, the Equation gives an answer for the number of alien civilisations in our Galaxy as anywhere from several to several million. I have a feeling Carl Sagan, one of the greatest advocates of the search for alien life, believed that there may have been around a thousand or so extraterrestrial civilisations out there in our Galaxy.

Astronomers have since found many tens, if not actually hundreds of extra-solar planets since then, some of which are rocky worlds like our own. This is very encouraging for SETI advocates and researchers, but later projects to search the sky using radio telescopes have still not found any conclusive evidence of alien intelligence.

As for missions to neighbouring stars, the costs of constructing a suitable spaceship that will get there in decades, rather than centuries or millennia, is immense. However, it has been estimated that the global economy should have grown sufficiently to make such a mission affordable by the 22nd Century A.D. Always supposing that Donald Trump and Kim Jong Un haven’t destroyed the world before then.