A novel approach plays with the peaks and troughs of the light waves to do the job more effectively. This week, in Nature, Eugene Serabyn of the Jet Propulsion Laboratory in California and his colleagues describe a stunning implementation of what is known as an optical vortex coronagraph. In place of a dark spot, this uses a disk of glassy material, etched with a carefully designed pattern which changes the phase of the incoming light, in effect twisting it back onto itself and creating a dark hole in the centre of the image. This blots out the starlight more effectively, making it easier to see any nearby planets.
In order for this technique to work, the distortions imposed on the incoming light during its passage through the Earth’s atmosphere must be removed using a trick called “wavefront correction”. The researchers did this using a small part of the giant Hale telescope in California, with which they examined a star called HR 8799 in the constellation of Pegasus. When images showing three planets orbiting this star were obtained in 2008, it was the first time exoplanets had been directly observed. The researchers could also see the planets—and their telescope was in effect five times smaller than the telescopes used in 2008.
With a two-metre telescope—small by modern astronomical standards—Dr Serabyn and his team say they could spot a planet 33 light-years away orbiting its host star at a similar distance to that at which the Earth orbits the Sun. Such a planet would fall into the so-called “Goldilocks zone” (neither too hot nor too cold) where the interesting chemistry should happen. As well as bringing planet-hunting within the reach of many smallish telescopes on Earth, the new technique also means that smaller, cheaper, or perhaps more numerous space telescopes—entirely free of deleterious atmospheric effects—could be employed to stretch out the eyes of men and finally fulfil Wren’s prediction.
Link thanks to Geekpress.