New laser technology could find Earth-like planets

April 8, 2008, Cambridge, MA--The leading method of finding planets orbiting distant stars spots mostly Jupiter-sized worlds. But a laser technology being developed by scientists and engineers at the Harvard-Smithsonian Center for Astrophysics (CfA), with colleagues at the Massachusetts Institute of Technology (MIT), will enable scientists to spot Earth-sized worlds in Earth-like orbits.

Apr 8th, 2008

April 8, 2008, Cambridge, MA--The leading method of finding planets orbiting distant stars spots mostly Jupiter-sized worlds. But a laser technology being developed by scientists and engineers at the Harvard-Smithsonian Center for Astrophysics (CfA), with colleagues at the Massachusetts Institute of Technology (MIT), will enable scientists to spot Earth-sized worlds in Earth-like orbits.

Planets orbiting other stars are much too faint and far away to be seen directly and photographed. Instead, astronomers must look for the planet's effect on its star: a slight wobble. The larger the mass of the planet, the bigger the star's wobble will be, making larger planets easier to detect. At the same time, a planet in a tight, short-period orbit is easier to find than one in a wide, long-period orbit.

Current technology, although very stable and sensitive, isn't quite up to the task of finding Earths. The best instruments can only find 5-Earth-mass planets in tight, Mercury-like orbits. But a new device developed by the CfA and MIT researchers, called an astro-comb, will be able to spot Earth-mass planets in Earth-like orbits. It uses ultrashort, femtosecond pulses of laser light, linked to an atomic clock, to provide a precise standard against which light from a star can be measured.

The astro-comb can make measurements accurate to one part in a trillion. This may increase the resolution of the wobble planet-hunting technique by about 100 times, which would allow astronomers to detect Earth-sized planets. The research is published in the April 3, 2008, issue of the journal Nature.

A prototype astro-comb will be tested this summer at CfA's Mount Hopkins Observatory in Arizona. Those tests will be used to refine the design. An improved astro-comb is destined for a project being built in the Canary Islands called the New Earths Facility. The researchers expect it to be operational sometime in 2010.

For more information, visit www.cfa.harvard.edu.


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