AI and photonics join forces to make it easier to find 'new Earths'

October 21, 2020

Australian scientists have developed a new type of sensor to measure and correct the distortion of starlight caused by viewing through the Earth's atmosphere, which should make it easier to study the possibility of life on distant planets.

Using artificial intelligence and machine learning, University of Sydney optical scientists have developed a sensor that can neutralise a star's 'twinkle' caused by heat variations in the Earth's atmosphere. This will make the discovery and study of planets in distant solar systems easier from optical telescopes on Earth.

"The main way we identify planets orbiting distant stars is by measuring regular dips in starlight caused by planets blocking out bits of their sun," said lead author Dr Barnaby Norris, who holds a joint position as a Research Fellow in the University of Sydney Astrophotonic Instrumentation Laboratory and in the University of Sydney node of Australian Astronomical Optics in the School of Physics.

"This is really difficult from the ground, so we needed to develop a new way of looking up at the stars. We also wanted to find a way to directly observe these planets from Earth," he said.

The team's invention will now be deployed in one of the largest optical telescopes in the world, the 8.2-metre Subaru telescope in Hawaii, operated by the National Astronomical Observatory of Japan.

"It is really hard to separate a star's 'twinkle' from the light dips caused by planets when observing from Earth," Dr Norris said. "Most observations of exoplanets have come from orbiting telescopes, such as NASA's Kepler. With our invention, we hope to launch a renaissance in exoplanet observation from the ground."

The research is published today in Nature Communications.


Using the new 'photonic wavefront sensor' will help astronomers directly image exoplanets around distant stars from Earth.

Over the past two decades, thousands of planets beyond our solar system have been detected, but only a small handful have been directly imaged from Earth. This severely limits scientific exploration of these exoplanets.

Making an image of the planet gives far more information than indirect detection methods, like measuring starlight dips. Earth-like planets might appear a billion times fainter than their host star. And observing the planet separate from its star is like looking at a 10-cent coin held in Sydney, as viewed from Melbourne.

To solve this problem, the scientific team in the School of Physics developed a 'photonic wavefront sensor', a new way to allow the exact distortion caused by the atmosphere to be measured, so it can then be corrected by the telescope's adaptive optics systems thousands of times a second.

"This new sensor merges advanced photonic devices with deep learning and neural networks techniques to achieve an unprecedented type of wavefront sensor for large telescopes,' Dr Norris said.

"Unlike conventional wavefront sensors, it can be placed at the same location in the optical instrument where the image is formed. This means it is sensitive to types of distortions invisible to other wavefront sensors currently used today in large observatories," he said.

Professor Olivier Guyon from the Subaru Telescope and the University of Arizona is one of the world's leading experts in adaptive optics. He said: "This is no doubt a very innovative approach and very different to all existing methods. It could potentially resolve several major limitations of the current technology. We are currently working in collaboration with the University of Sydney team towards testing this concept at Subaru in conjunction with SCExAO, which is one of the most advanced adaptive optics systems in the world."


The scientists have achieved this remarkable result by building on a novel method to measure (and correct) the wavefront of light that passes through atmospheric turbulence directly at the focal plane of an imaging instrument. This is done using an advanced light converter, known as a photonic lantern, linked to a neural network inference process.

"This is a radically different approach to existing methods and resolves several major limitations of current approaches," said co-author Jin (Fiona) Wei, a postgraduate student at the Sydney Astrophotonic Instrumentation Laboratory.

The Director of the Sydney Astrophotonic Instrumentation Laboratory in the School of Physics at the University of Sydney, Associate Professor Sergio Leon-Saval, said: "While we have come to this problem to solve a problem in astronomy, the proposed technique is extremely relevant to a wide range of fields. It could be applied in optical communications, remote sensing, in-vivo imaging and any other field that involves the reception or transmission of accurate wavefronts through a turbulent or turbid medium, such as water, blood or air."
DOWNLOAD a copy of the paper and photos of the research team at this link.


Dr Barnaby Norris |

Associate Professor Sergio Leon-Saval |


Marcus Strom | | +61 423 982 485


'An all-photonic focal-plane wavefront sensor' Nature Communications DOI: 10.1038/s41467-020-19117-w

Authors: Barnaby Norris, Jin Wei, Christopher Betters, Alison Wong, Sergio Leon-Saval (All affiliations: University of Sydney)


The authors declare no external funding.

University of Sydney

Related Planets Articles from Brightsurf:

Stars and planets grow up together as siblings
ALMA shows rings around the still-growing proto-star IRS 63

Two planets around a red dwarf
The 'SAINT-EX' Observatory, led by scientists from the National Centre of Competence in Research NCCR PlanetS of the University of Bern and the University of Geneva, has detected two exoplanets orbiting the star TOI-1266.

Some planets may be better for life than Earth
Researchers have identified two dozen planets outside our solar system that may have conditions more suitable for life than our own.

Fifty new planets confirmed in machine learning first
Fifty potential planets have had their existence confirmed by a new machine learning algorithm developed by University of Warwick scientists.

Rogue planets could outnumber the stars
An upcoming NASA mission could find that there are more rogue planets - planets that float in space without orbiting a sun - than there are stars in the Milky Way, a new study theorizes.

Could mini-Neptunes be irradiated ocean planets?
Many exoplanets known today are ''super-Earths'', with a radius 1.3 times that of Earth, and ''mini-Neptunes'', with 2.4 Earth radii.

As many as six billion Earth-like planets in our galaxy, according to new estimates
There may be as many as one Earth-like planet for every five Sun-like stars in the Milky way Galaxy, according to new estimates by University of British Columbia astronomers using data from NASA's Kepler mission.

How planets may form after dust sticks together
Scientists may have figured out how dust particles can stick together to form planets, according to a Rutgers co-authored study that may also help to improve industrial processes.

Planets around a black hole?
Theoreticians in two different fields defied the common knowledge that planets orbit stars like the Sun.

The rare molecule weighing in on the birth of planets
Astronomers using one of the most advanced radio telescopes have discovered a rare molecule in the dust and gas disc around a young star -- and it may provide an answer to one of the conundrums facing astronomers.

Read More: Planets News and Planets Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to