Light Canceling Chip Could Enable Us To See Exoplanets In Infrared

Astronomers have announced the creation of a chip that may allow direct observations of planets in the process of formation. The team is now working on a version that might be able to see whether Earth-like planets have a key indicator of life in their atmospheres.

Although we have, under rare circumstances, been able to detect the light from planets circling other stars (exoplanets) directly, anything even the most powerful telescopes can pick up is usually lost in the glare of the parent star.

Dr Steven Madden of the Australian National University is working on a solution using the same principles as noise-canceling headphones. “This chip is an interferometer that adds equal but opposite light waves… which cancels out the light from the Sun, allowing the much weaker planet light to be seen,” Madden said in a statement.

Other astronomers have been working along similar lines for a while. However, Madden told IFLScience existing versions only work for visible light and the near-infrared. The materials used in these cases absorb far infrared radiation, which is where many of the answers to our biggest astronomical questions lie, so Madden turned to chalcogenide glass, which is transparent at longer wavelengths.

Planets emit energy primarily in the infrared when forming, so we need to observe at those wavelengths if we want to learn more about this process. Madden’s chip, announced at the Australian Institute of Physics Congress, operates at 4 microns, which Madden described to IFLScience as “a perfect wavelength for finding protoplanets”. A preprint of an Optics Express paper on the work is available on

Further components are required for the chip to be able to process the light collected by an infrared telescope, and Madden says these are proving more challenging than similar achievements in visible light. Soon however, he hopes to have a complete system that can be attached to the giant Subaru telescope, whose adaptive optics make it ideal to use for planet hunting.

Maddon is also working on a version that operates at 10 microns, which might help us find extraterrestrial life. Ozone absorbs infrared radiation at a wavelength of 10 microns. Astronomers looking at Earth from many light-years away could, with the light-canceling chip operating around 10 microns, see a planet emitting at wavelengths above and below 10, and a substantial dip where ozone absorption occurs.

Ozone doesn’t last long in an atmosphere, so its presence indicates continuous formation, which we anticipate to be from photosynthesizing plants, bacteria or their alien equivalents. Consequently, such a dip would be a strong indication a planet supports life.

Carbon dioxide absorbs at 4.2 microns, so Madden might even learn if a planet had a greenhouse effect.

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