To Find Alien Worlds, First Look at Our Sun
Artist's impression of exoplanet Kepler-186f, a planet similar in size to the Earth and orbiting in what could be the habitable zone of its parent star.
One well-trusted method of finding an exoplanet is to see how much wobble it induces in its parent star. Right now, the state of the art precision for detecting planets a few dozen light-years away via this method is about one meter per second, which is produced by planets more massive than Earth. But if something disturbs the surface of the star — say, a sunspot — this can mess with the measurements and produce false positives.
A team of researchers is hoping to get around this by doing a test study on our own sun. If it works out, their project will allow them to detect Venus orbiting the sun using this "radial velocity" technique. This will be a proof of concept for finding Earth-size or smaller planets around other stars.
"We decided to build an instrument that was able to get radial velocity of the sun as if it was another star," said Xavier Dumusque, an astrophysicist and data scientist at Geneva Observatory, in an e-mail to Discovery News. He co-led the study with David F. Phillips of the Harvard-Smithsonian Center for Astrophysics.
"The sun is extremely close," he added, "so we can resolve its surface and therefore see the different sunspots on its surface. By comparing resolved images of the sun and the radial velocity obtained with this new instrument, we hope to understand better the effect of sunspots on radial velocity measurements, and find optimal correction techniques applicable to other stars."