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Tau Ceti's planets nearest around single, Sun-like star


Artists' conception of Tau Ceti solar systemAn artist's impression shows the five-planet system; from there, our Sun appears in the constellation Bootes

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The nearest single Sun-like star to the Earth hosts five planets - one of which is in the "habitable zone" where liquid water can exist, astronomers say.
Tau Ceti's planetary quintet - reported in an online paper that will appear in Astronomy and Astrophysics - was found in existing planet-hunting data.
The study's refined methods of sifting through data should help find even more far-flung worlds.
The star now joins Alpha Centauri as a nearby star known to host planets.
In both those cases, the planets were found not by spying them through a telescope but rather by measuring the subtle effects they have on their host stars' light.

Exoplanets

Artist's impression of an exoplanet
  • An exoplanet is a planet that exists outside our Solar System
  • Most are giant planets believed to resemble Jupiter or Neptune
  • The first exoplanet was discovered in 1992, orbiting a pulsar
  • A few years later, the planet 51 Pegasi B was found orbiting a star similar to the Sun
  • Hundreds of extrasolar planets have been found since
In the gravitational dance of a planet around a star, the planet does most of the moving. But the star too is tugged slightly to and fro as the planet orbits, and these subtle movements of the star show up as subtle shifts in the colour of the star's light we see from Earth.