This Device Blocks Starlight – And Could Help Us Spot Life Beyond Earth

Cool! That makes it sound like it's talking about a coronagraph, which is a piece of equipment made to block out light from a star so we can see directly the much smaller planets that orbit it. Want a brief explanation of how it functions or contributes to the Awesome! A quick breakdown is as follows: What exactly is a coronogram? A coronagraph is a telescope attachment that blocks a star's bright light, similar to raising your hand to block the sun so you can see something nearby. Exoplanets and other faint objects close to stars can be observed thanks to this. Why is Starlight blocked? Planets that orbit stars are millions to billions of times brighter than stars. It is nearly impossible to see the planets directly due to that glare. Planets that would otherwise be obscured are made visible thanks to the coronagraph's reduction of this glare. How Does This Aid in Obtaining Life? An exoplanet's light can be analyzed once we are able to see it, looking for specific wavelengths that could indicate the presence of water vapor, oxygen, methane, or other potential life signs (called biosignatures). Bonus: Where Do You Use This? To test this technology in space, NASA's Nancy Grace Roman Space Telescope, which will launch in a few years, will have a next-generation coronagraph. It could change the way we look for worlds that are habitable. Want me to demonstrate how coronagraphs stack up against other approaches to finding exoplanets? for ever?Awesome! Here's a quick

What is a Coronagraph?

A coronagraph is a telescope attachment that blocks the bright light of a star, kind of like holding your hand up to block the sun so you can see something next to it. This allows astronomers to see faint objects near stars, like exoplanets.

Why Block Starlight?

Stars are millions to billions of times brighter than the planets orbiting them. That glare makes it almost impossible to see the planets directly. The coronagraph reduces that glare, revealing planets that would otherwise be invisible.

How Does This Help Find Life?

Once we can actually see an exoplanet, we can analyze its light — looking for specific wavelengths that might indicate the presence of water vapor, oxygen, methane, or other potential signs of life (called biosignatures).

Bonus: Where is This Used?

NASA’s Nancy Grace Roman Space Telescope (launching in the next few years) will have a next-gen coronagraph to test this tech in space. It could revolutionize how we search for habitable worlds.

Want me to show how coronagraphs compare to other methods of finding exoplanets?Scientists have developed a breakthrough coronagraph that could finally allow us to see Earth-like exoplanets hidden in the blinding glare of their stars.

The video shows theoretical and experimental results from using the new method for direct imaging measurements of an artificial exoplanet (white crosshairs) passing in front of a simulated star. The new coronagraph design made it possible to estimate the position of artificial exoplanets with distances from their host star up to 50 times smaller than what the telescope’s resolution limit would normally allow. Credit: Nico Deshler, University of Arizona

Challenges in Direct Observation

Optically analyzing exoplanets poses a formidable challenge because, at astronomical scales, they are often too close to their parent star for current telescopes to resolve. Exoplanets can also be orders of magnitude dimmer than their host star. Although astronomers have developed various ways to indirectly infer the presence of a planet around a prospective star, directly observing exoplanets in images would be ideal.

With NASA’s next-generation space telescope, the Habitable Worlds Observatory (HWO), being dedicated to exoplanet science, many coronagraph designs have emerged, each with different practical and theoretical performance trade-offs. At the same time, recent work has shown that traditional notions of resolution for telescopes do not reflect fundamental limits and can be circumvented with careful optical pre-processing.

Inspired by these developments, the researchers decided to use a spatial mode sorter available in their lab to develop an improved coronagraph that theoretically rejects all the light from an on-axis star while achieving maximal throughput of an off-axis exoplanet.

Coronagraph Based on Spatial Mode Sorting

To capture an image of the exoplanet without the star, the new coronagraph design uses a mode sorter to isolate and eliminate light from the star and an inverse mode sorter to recompose the optical field after the starlight is rejected. Credit: Nico Deshler, University of Arizona

Filtering Light Like Musical Notes

Much like piano notes emit different acoustic frequencies, light sources in space excite different spatial modes — unique shapes and patterns of oscillation — depending on their position. The researchers separated these different modes using a mode sorter to isolate and eliminate light from a star and an inverse mode sorter to recompose the optical field after the starlight is rejected. This made it possible to capture an image of the exoplanet without the star.