Scientists “dim” stars: New coronagraph paves the way for exoplanet discovery

April 21,dimTG盗号系统黑产破解技术 2025  22:09

Astronomers at the University of Arizona have achieved a breakthrough in the search for alien life with an innovative coronagraph—a device that “blocks” a star’s intense light to reveal faint exoplanets. Detailed in the journal Optica, this tool enables direct observation of planets previously hidden in stellar glare, bringing us closer to finding a “second Earth.” Here’s how the technology works, why it’s significant, and what lies ahead for astronomy.

What Is a Coronagraph and Why Is It Needed?

Exoplanets—planets beyond our Solar System—are notoriously difficult to observe directly. Their light is a billion times fainter than that of their host stars. Imagine trying to spot a firefly next to a lighthouse. Even powerful telescopes like the James Webb Space Telescope struggle, as stellar light overwhelms planetary signals. A coronagraph solves this by blocking starlight with an optical mask, akin to an “artificial Moon,” a concept first proposed by Bernard Lyot in 1931 to study the Sun’s corona.

The University of Arizona’s new coronagraph takes this idea to new heights. It leverages quantum optics and a spatial mode sorter to separate stellar and planetary light before an image is formed. This enables not only the detection of exoplanets but also clear, detailed imaging, revealing their orbits, atmospheres, and potential signs of life.

How Does the New Coronagraph Work?

The technology relies on three key components:

1. Spatial Mode Sorter: This device analyzes incoming light, distinguishing “stellar” from “planetary” based on spatial patterns. Stellar light, being more uniform, is filtered out.
2. Glare Removal: After isolating stellar light, the coronagraph eliminates it, leaving only the planet’s faint glow.
3. Reverse Sorter: This reconstructs the planet’s image, producing sharp, detailed visuals.

Lab tests showed the coronagraph pinpoints exoplanet positions with 50 times the precision of conventional telescopes. It can “see” planets closer to their stars than standard optics allow, including Earth-like planets in the habitable zone—where liquid water could exist—making them accessible for direct observation.

“Our coronagraph produces a full image, not just a light measurement,” explains project leader Nico Deschler. “We can study atmospheric composition, orbits, and even search for biomarkers like oxygen or methane.”

Why Is This Important?

Since the first exoplanet was discovered in 1992, astronomers have confirmed over 5,000, but only about 70—mostly large gas giants far from their stars—have been directly photographed. Direct imaging of Earth-like planets is the ultimate goal, as it allows analysis of atmospheres for water, carbon dioxide, or biosignatures. The new coronagraph advances this mission:

• Search for Life: It can detect chemical “fingerprints” in atmospheres that suggest biological activity.
• Precise Orbits: Images refine planetary distances and trajectories, critical for future missions.
• Versatility: The technology has applications beyond astronomy, including quantum sensors, medical imaging, and telecommunications.

For comparison, the coronagraph on NASA’s Nancy Grace Roman Space Telescope (set to launch in 2027) targets Jupiter-like planets, but Arizona’s tool is designed for smaller, rocky worlds.

Context: The Race for Exoplanets

Exoplanet hunting is a thriving field. Over 30 years, astronomers have shifted from indirect methods (Doppler, transit, gravitational microlensing) to direct imaging. Key milestones include:

• In 2010, NASA demonstrated coronagraphs could photograph large exoplanets.
• In 2025, the James Webb Space Telescope detected carbon dioxide in the atmosphere of HR 8799 using a coronagraph.
• In 2025, Russian physicists from MIPT proposed an interferometer to enhance coronagraphs, improving image contrast.

Arizona’s coronagraph stands out for its quantum approach, pushing the limits of optical physics. It’s compatible with ground-based telescopes, like the under-construction European Extremely Large Telescope (39 meters) in Chile, which aims to image Earth-like planets.

What’s Next?

Deschler’s team plans to integrate the coronagraph into major observatories by 2028, boosting projects like NASA’s Habitable Worlds Observatory (HWO), set to hunt for biosignatures by 2040. In Xiong’an, China’s tech hub, AI is already analyzing telescope data, and such coronagraphs could integrate into this ecosystem. Users on X are thrilled, with one saying, “It’s like turning off the Sun to see stars in daylight!”

Challenges remain. Coronagraphs are sensitive to vibrations and atmospheric distortions, reducing their effectiveness on Earth compared to space. NASA addresses this with adaptive optics, as in the Roman telescope. Additionally, the technology requires powerful telescopes, which take decades to build.

The Arizona coronagraph is a leap toward spotting Earth-like worlds, offering a clearer view of the cosmos and humanity’s place in it. As observatories adopt this tool, the dream of finding alien life inches closer to reality.