28 new extrasolar planets discovered

The world's leading team of planet-hunters has announced the discovery of 28 new planets outside our solar system. They are among 37 objects outside our solar system found to orbit distant stars. Seven of the objects are confirmed brown dwarfs - failed stars much more massive than the largest planet - and two are borderline and could be small brown dwarfs or large planets. Jason Wright of the University of California announced the team's results yesterday at the annual meeting of the American Astronomical Society in Honolulu. "Taken together, in the last year our teams have increased the number of known planets by 12% and shown that at least 30% of stars known to host planets have more than one object orbiting." He explained his team's success as a testament to the advances in observing technology. "Planet hunting is getting much more sophisticated. Our primary technique, observing the small, reflex motions of a star as a planet orbits it, has improved greatly in the past 15 years. Today we can detect changes in the motion of some stars of only one metre per second."

Scientists were getting to the stage that, if they were observing our own solar system from afar, their telescopes could detect Jupiter. They have recorded more than 200 planets outside our solar system. One of the highlights is a detailed analysis of a planet circling the star Gliese 436, 30 light years from Earth. Working with colleagues in Europe, Dr Wright's team calculated that the planet was an ice giant of at least 22 Earth masses, which makes it slightly more massive than Neptune.