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Extrasolar planets

With a coarse-tooth comb

Nature volume 452, pages 538–539 (2008)Cite this article

The search for Earth-like planets outside our Solar System is bedevilled by the lack of an adequate frequency standard for calibrating starlight. Tweaking existing laser 'frequency combs' could be a way forward.

As we look for planets orbiting other suns, it is often tiny, periodic shifts in the spectrum of light coming from a star — a tell-tale 'Doppler wobble' — that reveals the presence of one or more smaller, unseen companions. But when it comes to finding Earth-like planets, this technique reaches a hurdle: the lack of a suitable frequency standard with which to measure the truly tiny spectral shifts caused by such very small planets. On page 610 of this issue, Li et al.1 take this matter in hand, adapting the optical comb — a technology developed to measure very high frequencies — to the purposes of astronomical measurements.

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Figure 1: Shifting stars.

References

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  1. Gordon Walker is emeritus professor in the Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia V6T 1Z1, Canada. gordonwa@uvic.ca,

    Gordon Walker

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  1. Gordon Walker
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Walker, G. With a coarse-tooth comb. Nature 452, 538–539 (2008). https://doi.org/10.1038/452538a

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