A striking new image from the European Southern Observatory (ESO) reveals the Milky Way arching over the Paranal Observatory in Chile, punctuated by vibrant green laser beams. These aren’t part of a sci-fi film; they are artificial guide stars used to sharpen astronomical observations.
The Very Large Telescope Complex
The image, captured by Chilean astrophotographer Alexis Trigo, showcases the ESO’s state-of-the-art telescope array. Four massive “Unit Telescopes” (UTs) – Antu, Kueyen, Yepun, and Melipal – dominate the landscape, each boasting an 8.2-meter primary mirror. These telescopes can operate individually or combined as the Very Large Telescope (VLT), offering unparalleled views of exoplanets and the distant cosmos. A smaller 1.8-meter auxiliary telescope adds to the complex, enhancing the VLT’s light-gathering power.
Correcting Atmospheric Distortion
The green lasers fired from UT-4 (Melipal) aren’t just for show. They climb approximately 56 miles into the upper atmosphere, exciting sodium atoms to create artificial reference points. Why is this important? Earth’s atmosphere distorts light from distant objects, blurring astronomical images. By tracking these laser-created “stars,” adaptive optics systems on the VLT’s mirrors can correct for this distortion in real-time.
This technique, pioneered by Melipal in 2016, has now been extended to all four UTs as of December 2025. The upgrade enhances the performance of the Very Large Telescope Interferometer (VLTI) and its advanced GRAVITY+ instruments, providing sharper images and more precise data.
This technology effectively removes the “shimmer” caused by the atmosphere, allowing astronomers to see deeper into space with greater clarity.
The ESO’s artificial star system is a crucial step toward overcoming the limitations of ground-based astronomy, pushing the boundaries of what we can observe in the universe.
