ESO photo shows lasers creating artificial stars above Chile observatory

New photo captures Milky Way over observatory

The European Southern Observatory (ESO) has released a new photo showing the Milky Way galaxy arching over its Paranal Observatory in Chile. The image, captured by astrophotographer Alexis Trigo, also shows four powerful lasers creating artificial stars in the dark sky.

These lasers are a key part of the observatory's advanced adaptive optics systems. They help astronomers correct for the blurring effects of Earth's atmosphere in real time.

The Very Large Telescope in focus

The photo prominently features the four main telescopes of the Very Large Telescope (VLT). Each of these Unit Telescopes houses a primary mirror measuring 8.2 meters in diameter.

The telescopes are named Antu, Kueyen, Yepun, and Melipal. They can operate independently or together as a single, more powerful instrument.

• Antu
• Kueyen
• Yepun
• Melipal

A smaller, 1.8-meter auxiliary telescope is visible in the foreground. It can be moved on rails to support the light-gathering work of the larger telescopes.

How the laser guide stars work

The four orange beams firing from the telescope named Melipal are sodium lasers. They are projected 56 miles (90 kilometers) into Earth's upper atmosphere.

At that altitude, the lasers excite sodium atoms, causing them to glow and create artificial "guide stars." Astronomers use these precise points of light to measure atmospheric distortion.

This data is then fed to deformable mirrors on the VLT. The mirrors adjust their shape hundreds of times per second to cancel out the blurring, resulting in sharper images of space.

A major upgrade for sharper vision

The telescope Melipal has used its guide star laser system since 2016. In a significant upgrade, the other three Unit Telescopes received their own lasers in December 2025.

This expansion creates a constellation of artificial stars. It greatly enhances the capabilities of the VLT Interferometer and its GRAVITY+ instrument.

The upgrade allows the entire observatory to correct for atmospheric turbulence more effectively than ever before. This is crucial for studying fine details on exoplanets and observing the deep universe.