European Southern Observatory Activates PoET Solar Telescope in Chile to Filter Stellar Noise from Exoplanet Data

The Paranal solar ESPRESSO Telescope achieves first light in Chile, using the Sun to help astronomers filter out stellar noise in the search for distant exoplanets.

By: AXL Media

Published: Apr 9, 2026, 9:31 AM EDT

Source: Information for this report was sourced from EurekAlert!

A New Strategic Lens for Planet Hunters

The European Southern Observatory has announced the successful first observations of the Paranal solar ESPRESSO Telescope, an instrument specifically designed to refine the search for Earth-like worlds. Located in the Atacama Desert of Chile, PoET serves as a specialized solar observer that bridges the gap between solar physics and exoplanetary science. By studying the Sun in extreme detail, astronomers hope to overcome the persistent challenge of host star interference, which often masks the presence of small, rocky planets orbiting distant stars.

Decoding the Interference of Stellar Activity

One of the primary obstacles in modern astronomy is the astrophysical noise produced by a star's own surface activity, such as sunspots and flares. These features can distort a star's spectrum, creating signals that either hide or erroneously mimic the presence of an orbiting exoplanet. According to Nuno Santos, the Principal Investigator for PoET, this noise is a critical barrier to characterizing other Earths. PoET is designed to identify these signatures at their source, providing a template that allows researchers to subtract similar interference from the light of distant solar-type stars.

The Dual Telescope Configuration for Spectral Clarity

PoET utilizes a sophisticated two-telescope design to capture a comprehensive view of solar behavior. The primary telescope features a 60-centimeter mirror capable of focusing on specific surface features, such as individual sunspot regions, with unprecedented resolution. Simultaneously, a smaller secondary telescope collects light from the entire solar disc. By analyzing these two data streams at once, researchers can determine exactly how localized surface activity influences the overall light output, creating a high-resolution guide for isolating planetary signals in night-sky observations.