Four More Potentially Habitable Planets Discovered Nearby
Only 12 light-years away from us, four Earth-size planets have been discovered that appear to have all they might need to support water – and maybe life.
The discovery of the planets, which was disclosed in a paper soon to be published in The Astronomical Journal, was made by observing wobbles in the path of Tau Ceti, the sunlike star that is closest to Earth. The planets are orbiting the star, which is also visible to the naked eye – unlike the four possible Earths that orbit around it.
To find the planets, an international team of astronomers studied the wobbles in the movement of Tau Ceti. To do so required technology that could pick up variations in the movement of the star that were as tiny as 30 centimeters per second.
What they found was perhaps one of the most significant discoveries of Earth-like planets. The planets are of relatively low mass, only about 1.7 times the mass of our Earth, and among the smallest planets ever detected near sunlike stars. Further analysis showed that two of the four planets are what the study team called “super-earths” and just happen to be in Tau Ceti’s “habitable zone.” That means these planets might support liquid surface water.
Finding the planets was quite challenging, requiring the development of special noise-reduction techniques to gather Tau Ceti’s wobble data with sufficient accuracy. The researchers also took careful time, making sure that what they had detected were the signs of, as they put it, “four rocky planets orbiting the star,” not just ghost signatures from the stellar outer surface.
Because of their similarity to our sun, the investigation of sunlike stars has long been considered the best possible way to find habitable Earth-like planets. These sunlike stars are also not so faint that any planets orbiting them would be what is known as “tidally locked,” which means the same side is also facing the star. With tidally locked planets, one side is continually bombarded with solar radiation while the other side is not, creating a number of ecological challenges for them – challenges that would tend to rule out the presence of liquid water.
The international team who discovered these planets includes lead author Fabo Feng of the University of Hertfordshire, UK; Stephen Vogt, professor of astronomy at the University of California, Santa Cruz; Mikko Tuomi of the University of Hertfordshire; John Barnes of The Open University, UK; Guillem Anglada-escude of Queen Mary University of London; and Paul Butler of the Carnegie Institution for Science, Washington, DC.
The discoveries are outlined in a paper soon to be published in The Astronomical Journal. A copy is also available online.